[0001] The present invention relates to a musical tone generating apparatus and, more particularly,
to a musical tone generating apparatus of a type such as a sine wave synthesizing
type for synthesizing a musical tone signal, by combining envelope-controlled component
wave signals of plurality of orders from a component wave generating means.
[0002] In a known conventional musical tone generating apparatus, envelopes respectively
corresponding to a plurality of sine waves as frequency components of the musical
tone are independently controlled to change tone colors as a function of time.
[0003] A musical tone generating apparatus of this type is described in e.g., U.S.P. No.
4,083,285.
[0004] In a conventional musical tone generating apparatus of this type, if a user can arbitrarily
manipulate envelopes of sine waves, musical performance effects can be naturally improved.
[0005] However, with the above application, the user must spend long time setting envelopes
in proportion to an increase in envelope flexibility or versatility. Overloading on
the user can be easily expected.
[0006] It is therefore, an object of the present invention to provide a musical tone generating
apparatus capable of producting envelope functions independently of respective component
wave signals in response to simple input operations.
[0007] In order to achieve the above object of the present invention, there is provided
a musical tone generating apparatus of a type for synthesizing a musical tone signal
by controlling envelopes of a plurality of component wave signals of orders from
component wave generating means in accordance with envelope functions of corresponding
orders, comprising:
common envelope setting means for supplying a common envelope function to the
plurality of component wave signals of the plurality of orders; and
envelope modifying means for modifying the common envelope function supplied
from the common envelope setting means into values of the plurality of orders, thereby
generating the envelope functions for controlling the envelopes of the component wave
signals.
[0008] In addition, in order to achieve a variety of tone colors, there is provided a musical
tone generating apparatus of a type for synthesizing a musical tone signal such that
envelopes are provided to a plurality of component wave signals by using independent
envelope functions, comprising:
first generating means for generating component wave signals of a plurality of
orders constituting a first group;
second generating means for generating component wave signals of a plurality of
orders constituting a second group;
global envelope setting means for supplying at least one type of global envelope
function;
first envelope modifying means for modifying the global envelope function from
the global envelope setting means, in accordance with its order, thereby generating
first envelope functions of the respective orders; and
second envelope modifying means for modifying the global envelope function from
the global envelope setting means in accordance with its order, thereby generating
second envelope functions of the respective orders,
wherein the component wave signals belonging to the first group are controlled
by the first envelope functions of the corresponding orders from the first envelope
modifying means, the component wave signals belonging to the second group are controlled
by the second envelope functions of the corresponding orders from the second envelope
modifying means, and the first envelope functions generated by the first envelope
modifying means and the second envelope functions generated by the second envelope
modifying means are independent of each other regardless of the orders.
[0009] According to the present invention, the user need not produce individual envelope
functions for the component wave signals of a plurality of orders in order to obtain
musical tones. For example, at a data input device such as a keyboard, the user selects
only one envelope function to obtain a variety of tone colors because a plurality
of envelope functions are generated on the basis of one envelope function (i.e., a
common or global envelope function) generated by an envelope modifying means. An envelope
function for controlling an envelope of a component wave signal of a given order is
obtained by modifying the common envelope function in accordance with a value of a
corresponding order of the component wave signal.
[0010] If a value of the common envelope function is given as
w and a value of the order is given as
x, the envelope modifying means performs modification represented by the following
function:
G(x,w)
The value of function G(x,w) is determined by parameter
x and parameter
w. The modified value of function G(x,w) is a value for the xth order envelope function.
That is, it is a value of the envelope function for controlling the envelope of the
xth order component wave signal. In other words, function G(x,w) provides a modification
characteristic for modifying the common envelope function into the envelope functions
of the respective orders.
[0011] In one example, if order value
x and value
w of the common envelope function are given, function G(x,w) can be calculated in accordance
with arithmetical and logical operations. In this case, the envelope modifying means
can be basically realized by a means for executing appropriate logical and/or arithmetical
algorithms.
[0012] In another example, modification characteristic function G(x,w) is solely determined
if order value
x and the value w of the common envelope function are given. However, this function
cannot be solved by arithmetic and logical operations or cannot be calculated for
at least a given combination of
x and
w. In this case, the envelope modifying means can be constituted by using a modification
table (e.g., a memory such as a ROM) in the range where calculations cannot be performed.
The modification table can also be used in the first example. A suitable construction
can be determined in consideration of a processing speed, an operation volume, and
a required memory capacity.
[0013] In a simple example, a monotonous function (e.g., monotonous for x - w = u, x/w =
u, x·w = u, and x + w = u, or monotonous for all parameters
u as a combination of the above arithmetic operations) can be used as modification
characteristic function G(x,w). In this case, logical operations (e.g., comparison,
AND, and OR) need not be performed. Only the arithmetical calculations can be performed.
[0014] In a more complicated example, modification characteristic function G(x,w) can be
defined as a function in which the characteristics are changed in ranges of values
of parameter
u if parameter
u is calculated by arithmetical operations using parameter
x of the order and parameter
w of the envelope function. In this case, an appropriate function is selected in accordance
with the value of parameter
u. For example, if u > 0, then monotonous function G₁(u) serves as a modification characteristic
function. If u ≦ 0, another monotonous function G₂(u) serves as a modification characteristic
function. In this case, logical operations are added to the arithmetical operations.
[0015] In either case, the envelope modifying means produces envelopes of respective orders
from the common envelope function. As a result, the user is free from production of
respective envelope functions for the corresponding component waves and can easily
produce musical tones.
[0016] The common envelope function input to the envelope modifying means can be expressed
in various forms. In a simplest example in digital techniques, an envelope function
can be given as a waveform data format (i.e., a sequence of digital data representing
the instantaneous values of the envelope levels). In many examples, the envelope
functions can be represented by compressed data (control information). For example,
an envelope function of a polygonal type is expressed as a set of position data of
polygonal points (e.g., this function is expressed by several step rate data and several
step level data). Not many envelope input devices are available to input envelope
functions in the form of waveform data. For example, when an envelope waveform is
drawn on an input device such as a tablet, A/D-converted data (data prior to data
compression) is expressed in the form of waveform data. The form of the input device
for inputting the common envelope function is not important to the present invention.
[0017] The form of modification processing varies in the envelope modifying means in accordance
with the form of expression of the input common envelope function. For example, in
a given arrangement, the envelope modifying means modifies the common envelope function
given in the form of digital waveform data into envelope functions of the respective
orders represented in the same form as the common envelope-function. That is, each
digital value of the common envelope function is modified into the corresponding digital
value of an envelope functions of each order. The modified envelope functions of the
respective orders which are expressed in the form of waveform data can be directly
inparted to a component wave signal in the form of waveform data. Alternatively, the
above envelope functions of the respective orders may be decoded into the envelope
function in the form of waveform data upon generation of a musical tone signal after
the envelope functions of the respective orders are compressed in the form of control
information. In another arrangement, the envelope modifying means modifies the common
envelope function given in the form of control information into the envelope functions
of the respective orders in the same form as the common envelope function. In this
case, in a simple example, the values of the control information (e.g., values of
rate data and level data for each step, or coordinates of each polygonal point) are
converted in accordance with modification characteristic function G(x,w), thereby
obtaining the envelope functions of the respective orders. In a more complicated example,
the modification characteristic function is also applied to points on a polygonal
line (these points can be easily calculated by arithmetical operations because the
common envelope function is defined by control information) in addition to polygonal
points, thereby obtaining points defining the envelope functions of the respective
orders.
[0018] The envelope function of each order modified by the envelope modifying means is finally
used to control the envelope of the component wave signal of the order corresponding
to the envelope function. This envelope control can be performed by a digital multiplier,
an analog multiplier, or a device for performing other functionally or equivalently
performing a multiplication.
[0019] According to the present invention, the component wave signal is not limited to the
sine wave signal but can be extended to any waveform signal having a frequency or
a frequency spectrum corresponding to the order. For example, a rectangular wave (e.g.,
a rectangular wave obtained by the Walsh function) can be used as a component wave
signal.
[0020] According to the specific form of the present invention, independent envelopes can
be given in units of groups of component waves, and musical tones with a variety of
tone colors can be obtained.
[0021] A means for establishing an independent relationship between an envelope function
for a component wave belonging to a given group (e.g., the first group) and that belonging
to another group (e.g., the second group) can be arranged in several specific forms.
In a given example, a global envelope setting means provides different global envelope
functions in units of groups. In this case, the user produces different envelopes
in units of component wave groups. The envelope modifying means for the first group
generates envelope functions of the respective orders on the basis of the first global
envelope function. The envelope modifying means for the second group produces envelope
functions of the respective orders on the basis of the second global envelope function.
With the above arrangement, independency of the envelopes of the different groups
can be established due to the following reason.
[0022] Assume the modification logical algorithm used in the first and second envelope modifying
means is the same and is given as Fx(W) where
x is the order and W is the global envelope function. In other words, Fx(W) is the
xth-order envelope function. The envelope modifying means modifies the global envelope
function in accordance with its orders. Condition Fx(W) ≠ Fy(W) is established between
envelope functions Fx(W) and Fy(W) having different orders
x and
y. However, if envelope functions have the same order, Fx(W) = Fx(W). In other words,
functions Fx(W) and Fy(W) depend on the orders (if identical global envelope functions
are assumed).
[0023] In the above case, the first global envelope function W1(t) and the second envelope
function W2(t) are independently determined by the user and are independent functions.
Functions obtained by modifying independent functions on the basis of the same modification
logical algorithm are independent. If the first envelope modifying means produces
xth-order envelope function {Fx(W1(t))} and the second envelope modifying means produces
xth-order envelope function Fx(W2(t)), condition Fx(W1(t)) ≠ Fx(W2(t)) is established.
Since functions W1(t) and W2(t) are independent, envelope function group {Fx(W1(t)).}
for controlling the component waves of the first group and envelope function group
{Fx(W2(t))} for controlling the component waves of the second group are independent.
[0024] In another arrangement, assume that modification logical algorithm Fx(W) of the first
envelope modifying means and modification logical algorithm Gx(W) of the second envelope
modifying means are independent or different. In this case, either envelope modifying
means can receive the same global envelope function. In other words, the global envelope
setting means can provide only one global envelope function.
[0025] In the same manner as described above, the envelope function group {Fx(W)} generated
by the first envelope modifying means to control the component waves of the first
group and envelope function group {Gx(W)} generated by the second envelope modifying
means to control the component waves of the second group are independent of each other.
[0026] In still another arrangement, a means can be used to modify a single global envelope
function set by the user into global envelope functions which are independent between
the groups. The global envelope function of each group is supplied to the corresponding
envelope modifying means. For example, global envelope function G(W) for the first
group is supplied to the first envelope modifying means and global envelope function
H(W) for the second group is supplied to the second envelope modifying means. With
this arrangement, either envelope modifying means (i.e., a means for modifying the
global envelope group into envelope functions of the respective orders) can employ
the same modification logical algorithm.
[0027] This invention can be more fully understood from the following detailed description
when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a block diagram showing the overall circuit arrangement according to an
embodiment of the present invention;
Fig. 2 is a block diagram showing a detailed circuit arrangement of an envelope-controlled
sine wave generator in the circuit shown in Fig. 1;
Fig. 3 is a table showing a key code conversion logic algorithm in a key code converter
in Fig. 2;
Fig. 4 is a map showing a format of envelope data stored in a global envelope memory
shown in Figs. 1 and 2;
Fig. 5 is a waveform chart showing an envelope generated by an envelope generator
in accordance with envelope data shown in Fig. 4;
Figs. 6(A) to 6(C) are waveform charts showing envelope modifications for obtaining
a low-pass filter type resonance effect in the envelope modification device in Fig.
2;
Figs. 7(A) and 7(B) are waveform charts showing other envelope modifications for obtaining
a high-pass filter type and band-pass filter type resonance effects in the envelope
modification device in Fig. 2;
Figs. 8(A) to 8(E) and Figs. 9(A) and 9(B) are waveform charts showing still other
envelope modifications for obtaining a low-pass filter effect in the envelope modification
device in Fig. 2;
Figs. 10(A) to 10(C) are waveform charts showing still other envelope modifications
for realizing a high-pass filter effect in the envelope modification device in Fig.
2;
Fig. 11 is a block diagram showing a partial modification of the circuit in Fig.
2;
Figs. 12(A) to 12(C) are waveform charts for explaining the operation of the envelope
modification device shown in Fig. 11;
Fig. 13 is a circuit diagram of a device arranged by further modifying part of the
envelope modification device in Fig. 2;
Figs. 14(A) to 14(D) are waveform charts showing still other envelope modifications
for obtaining characteristics for modifying the envelope by only levels in the device
shown in Fig. 11; and
Fig. 15 is a block diagram showing an overall circuit arrangement according to another
embodiment of the present invention.
[0028] A few preferred embodiments of the present invention will be described in detail
hereinafter. These embodiments exemplify sine wave synthesis type musical tone generating
apparatuses.
[0029] The first embodiment will be described below. Fig. 1 shows the overall circuit arrangement
of a sine wave synthesis type musical tone generating apparatus. Referring to Fig.
1,
n envelope-controlled sine wave generators 15-1 to 15-n are connected to keyboard
1 serving as a performance input device, data input device 2 for inputting various
data, and global envelope memory (common envelope memory) 3. Envelope-controlled
sine wave generators 15-1 to 15-n are arranged to generate sine waves having independent
frequencies on the basis of harmonic data set by a user at data input device 2. Global
envelope memory 3 comprises a RAM and stores global envelope function data set at
data input device 2. The global envelope is modified by the circuit constructed in
the sine wave generators 15-1 to 15-n into envelope function data depending on their
assigned frequencies (i.e., orders). The sine waves generated in generators 15-1 to
15-n are envelope-controlled by the modified envelope data.
[0030] In this embodiment, when the user sets one global envelope function,
n independent envelope functions can be obtained for the preset global envelope function.
The user need not set
n envelopes for the respective sine waves, thereby reducing envelope producing labor.
[0031] Envelope-controlled sine wave data from envelope-controlled sine wave generators
15-1 to 15-n are added by adder 16, and a sum signal (musical tone signal) is converted
into an analog signal by D/A converter 17. The analog signal is produced as a tone
through amplifier 18 and loudspeaker 19.
[0032] The detailed arrangement of each envelope-controlled sine wave generator is shown
in Fig. 2. The arrangement surrounded by the dotted line and denoted by reference
numeral 15 represents one of envelope-controlled sine wave generators 15-1 to 15-n.
Referring to Fig. 2, key code generator 4 generates a key code corresponding to the
depressed key at keyboard 1. Key code converter 5 converts the generated key code
in accordance with a value in harmonic data memory 10. Memory 10 can store harmonic
data (harmonic orders) of 0 to 31 which can be set by the user at data input device
2. Key code converter 5 converts the key code using the stored harmonic data in accordance
with a method shown in Fig. 3. For example, if harmonic data represents 1, the key
code is converted into another key code representing a second harmonic which represents
a tone higher by one octave than the original tone. Phase angle generator 6 comprises
a frequency data ROM and an accumulator and causes the frequency data ROM to convert
the key code from key code converter 5 into frequency data, and the accumulator to
accumulate the frequency data so as to generate a phase angle corresponding to the
key code, thereby reading out sine wave data from sine wave ROM 7. An output from
sine wave ROM 7 is a sine wave signal having a frequency corresponding to the order
of a harmonic set in harmonic data memory 10. In this embodiment, the key code is
converted in accordance with the harmonic data. However, frequency data may be converted
into frequency data corresponding to the harmonic in accordance with bit shifting
or the like. Alternatively, the value of the phase angle output from phase angle generator
6 may be converted to obtain a phase angle representing the corresponding order. In
this manner, various circuit modifications may be proposed.
[0033] Fixed amplitude memory 11 comprises a RAM for storing data for controlling (scaling)
the amplitude of the sine wave signal from sine wave ROM 7 regardless of time changes.
Scaling data can be input by the user at data input device 2. Scaling data stored
in fixed amplitude memory 11 represent independent values for envelope-controlled
sine wave generators 15-1 to 15-n. Therefore, when the sine wave data from sine wave
ROM 7 is multiplied by each multiplier 8 with the data read out from fixed amplitude
memory 11, relative amplitudes of
n sine wave signals can be independently controlled.
[0034] The amplitude-controlled sine wave signal from multiplier 8 is multiplied with an
envelope signal output from envelope modification device 14 (to be described in detail
later). Therefore, amplitude control as a function of time can be performed, and the
product is output from envelope sine wave generator 15.
[0035] As described above, global envelope memory 3 stores common global envelope function
data for
n envelope-controlled sine wave generators 15-1 to 15-n. The global envelope function
in global envelope memory 3 can be expressed by 4-step rate data and 4-step level
data (Fig. 4). The global envelope function in this form is modified into the form
of waveform data by envelope generator 12 (Fig. 5). More specifically, envelope generator
12 comprises an accumulator and a comparator and receives step-1 rate data of step-1
level data from global envelope memory 3. The rate data is repetitively accumulated.
If the accumulation result reaches the level data, envelope generator 12 receives
step-2 rate data and step-2 level data from global envelope memory 3. The above operations
are repeated to obtain waveform data of the global envelope.
[0036] Envelope modification device 14 modifies the waveform data of the common global envelope
function generated by envelope generator 12 into waveform data of envelope functions
of the respective orders in accordance with harmonic data (order) from harmonic data
memory 10. For example, if the harmonic data from harmonic data memory 10 in envelope-controlled
sine wave generator 15 is 1 (i.e., this value represents a second harmonic), the first-order
envelope waveform data is generated by envelope modification device 14. The first-order
envelope waveform data is multiplied with a sine wave signal having a frequency of
the second harmonic, thereby controlling the envelope.
[0037] The arbitrary modification characteristic of envelope modification device 14 can
be provided in principle. In practice, the modification characteristic for a resonance
effect will be described first.
[0038] Assume that
x is the order, i.e., the value of the harmonic data from harmonic data memory 10,
that w(t) is the global envelope function, i.e., the output from envelope generator
12, and that R is the depth of resonance. Xth-order envelope function Fx(t) modified
by envelope generator 12 satisfies the following conditions:
(a) If x < w(t) and f(x-w(t)) + R < 1, then Fx(t) = 1
(b) If x ≧ w(t) or f(x-w(t)) + R ≧ 1, then Fx(t) = f(x-w(t)) + R (if f(x-w(t)) + R
< 0, then Fx(t) = 0)
[0039] A substitution of x-w(t) into
u yields the following conditions for f(u):
(c) If u < 0, then fʹ(u) > 0
(d) If u = 0, then f(u) = 1
(e) If u > 0, then fʹ(u) < 0
Therefore, if u = 0, i.e. if the order value
x is equal to value W(t) of the global envelope function, f(u) takes the maximum value.
The value of f(u) is decreased when the absolute value of difference
u is increased.
[0040] Xth-order envelope function Fx(t) is expressed as a function of time
t. When xth-order envelope function Fx(t) is expressed as a function of difference
u, function F(u) is derived. The value of function F(u) is changed in accordance with
order
x relative to value W(t) of global envelope function at arbitrary time
t. Therefore, function F(u) determines the modification characteristic for modifying
the global envelope function into envelope functions of the respective orders. An
example of modification characteristic function F(u) is shown in Fig. 6(A). A difference
obtained by subtracting the value of global envelope function W(t) from order
x is plotted along abscissa
u. As shown in Fig. 6(A), near u = 0, i.e, in the range of order
x closer to the value of global envelope function W(x), F(u) is amplified. However,
if u « 0, then F(u) = 1. If u » 0, then F(u) = 0. Therefore, modification characteristic
function F(u) provides a resonance effect for emphasizing the component closer to
the cutoff frequency of the low-pass filter.
[0041] The resonance effect can be dynamically given. More specifically, the value of global
envelope function W(t) is changed as a function of time
t. When specific order x₀ is given, a value obtained by subtracting W(t) from order
x₀ is also changed as a function of time along the u-axis in Fig. 6(A). The value
of each F(u), i.e., value Fx₀(t
i) of the x₀th-order envelope function at time t
i is also changed. According to Fig. 6(A), the value of Fx₀(t
i) is one (1) and is not thus attenuated if order
x is sufficiently smaller (lower) than value W(t
i) of the global envelope function at time t
i. However, if order
x is sufficiently larger (higher) than value W(t
i) of the global envelope function at time t
i, the value of FX₀(t
i) is zero and is thus perfectly attenuated. If order
x is very close to value W(t
i) of the global envelope function at time ti, the value of Fx₀(t
i) can be amplified to a value of one or more.
[0042] In other words, the order of an envelope function having an amplified value at a
given time is close to the value of the global envelope function at the given time.
Therefore, the order of the emphasized component wave is changed as a function of
time, thereby obtaining the resonance effect which is dynamically changed as a function
of time.
[0043] Modification into envelope functions of the respective orders will be described
in detail. Assume that global envelope function W(t) shown in Fig. 6(B) is supplied
from global envelope memory 3 through envelope generator 12. Specific order x₀ has
a dotted level. In this case, envelope modification device 14 shown in Fig. 2 produces
x₀th-order envelope function Fx₀(t) shown in Fig. 6(C) in accordance with modification
characteristic F(u) shown in Fig. 6(A).
[0044] In order to readily understand modification, the values of x₀th-order envelope function
Fx₀(t) which correspond to several values of global envelope function W(t) shown in
Fig. 6(B) are written in Fig. 6(A). For example, as shown in Fig. 6(B), values W(t₁)
and W(t₂) of the global envelope function are equal to the value of order x₀ at times
t₁ and t₂. Therefore, u = 0 is established. The value of F(u) at position for u =
0 in Fig. 6(A) are values Fx₀(t₁) and Fx₀(t₂) of the x₀-th order envelope function
at times t₁ and t₂. The values of x₀th-order envelope function Fx₀(t) at other times
can be obtained in the same manner as described above.
[0045] In practice, envelope modification device 14 shown in Fig. 2 performs modifications
for all data values of global envelope function W(t) in the form of waveform data
supplied from envelope generator 12.
[0046] Envelope modification device 14 can be arranged in various ways. For example, device
14 can comprise a subtracter for calculating a difference between the instantaneous
value of global envelope function W(t) from envelope generator 12 and the value of
order
x from harmonic data memory 10, and a memory addressed in response to output data from
the subtracter and adapted to store modified envelope function waveform data values.
Alternatively, if modification characteristic function F(u) or f(x-W(t)) is a function
to be calculated, envelope modification device 14 can be achieved by a proper algorithm.
For example, a difference between the order value
x and the value of the global envelope function is calculated such that u = x - W(t).
By utilizing difference
u, f(x-W(t)) is calculated and is added to resonance value R, thereby obtaining f(x-W(t))
+ R. Whether difference
u is negative is determined or whether f(x-W(t)) + R is 1 or less is determined. If
both these conditions are established (corresponding to x < W(t) and f(x-W(t)) + R
< 1), constant 1 is used as the modified envelope function value. If neither conditions
are established (corresponding to x ≧ W(t) or f(x-W(t) + R ≧ 1), whether f(x-W(t))
+ R is negative is determined. If value f(x-W(t)) + R is not negative, this value
serves as the modified envelope function value. If value f(x-W(t)) + R is negative,
constant 0 serves as the modified envelope function value.
[0047] Modification characteristic F(u) of the global envelope function/envelope functions
of the respective orders is not limited to ones shown in Fig. 6(A) or in modification
conditions (a) to (e). The illustrated modification characteristic is an example for
obtaining a low-pass filter type resonance effect. For example, within the range of
u « 0, the characteristic is perfectly flat since F(u) = 1. However, the characteristic
may be almost flat. The position for u = 0, i.e., x = W(t) is the center of resonance.
However, x = W(t) + K (where K is a constant) may be the central position of the resonance.
Alternatively, cx = W(t) (where
c is a constant or cx is an increment function of
x) may be the central position of the resonance. In the former case, (x-K) can be evaluated
as the value of order
x. In the latter case, cx can be evaluated as the value of order
x.
[0048] Modification characteristic F(u) may be selected to obtain a high-pass filter type
resonance effect in place of the low-pass filter type resonance effect.
[0049] A modification characteristic for the high-pass filter type resonance effect is shown
in Fig. 7(A). This modification characteristic is obtained by changing conditions
(a) and (b) of conditions (a) to (e) and using the following condition in place of
condition (a):
[0050] If x > W(t) and f(x-W(t)) + R < 1, then Fx(t) = 1 and the following condition in
place of condition (b):
[0051] If x ≦ W(t) or f(x-W(t)) + R ≧ 1, then Fx(t) = f(x-W(t)) + R
(if f(x-W(t)) + R < 0, then Fx(t) = 0)
[0052] Modification characteristic F(u) may be selected to obtain a band-pass filter type
resonance effect, as shown in Fig. 7(B).
[0053] The modification characteristic for the band-pass filter type resonance effect is
obtained by using conditions (c), (d), and (e) of conditions (a) to (e) without changes
and the following condition in place of conditions (a) and (b):
Fx(t) = f(x-W(t)) + R
(if f(x-W(t)) + R < 0, then Fx(t) = 0)
[0054] Resonance value R need not be a constant but a variable which can be changed by the
user. In this case, the resonance value can be preferably changed in real time during
musical performance in the following manner. When envelope modification device 14
shown in Fig. 2 is used, changing resonance value R is used in the process for producing
envelope functions Fx(t) of the respective orders in the form of waveform data from
global envelope function W(t) in the form of waveform data.
[0055] The operation of envelope modification device 14 in Fig. 2 will be described when
waveform data of envelopes of the respective orders for obtaining a low-pass filter
effect is to be generated.
[0056] In this case, envelope modification device 14 performs the following modifications
to produce envelopes of the respective orders:
(f) If x ≦ W(t), then Fx(t) = 1
(g) If x > W(t), then Fx(t) = f(x-W(t))
(if f(x-W(t)) < 0, then Fx(t) = 0) where x is the order (corresponding harmonic data), W(t) is the global envelope function
(output from envelope generator 12), and Fx(t) is the modified envelope function (output
from envelope modification device 14). Let x-W(t) be u, then f(u) satisfies the following conditions:
(h) If u = 0, then f(u) = 1
(i) If u > 0, then fʹ(u) < 0
[0057] When order
x is smaller than the value of global envelope function W(t), Fx(t) is 1. However,
when order
x is larger than the value of global envelope function W(t), the gradient of Fx(t)
is negative. An example of this function is shown in Fig. 8(A). Fig. 8(A) shows the
characteristic of function Fx(t) when order
x is plotted along the abscissa. Although function W(t) is a function of the global
envelope function, its value is changed as a function of time
t. If specific order x₀ is given, the value of x₀th-order envelope function Fx₀(t)
is changed in accordance with the value at each time of global envelope function W(t).
In the range of x₀ ≦ W(t), x₀th-order envelope function Fx₀(t) is not attenuated.
However, in the range of x₀ > W(t), the function is greatly attenuated when a difference
between x₀ and W(t) is larger.
[0058] Assume that global envelope function W(t) shown in Fig. 9(A) is supplied from global
envelope memory 3 through envelope generator 12. Specific order x₀ has the dotted
level. In this case, x₀th-order envelope modification device 14 generates x₀th-order
envelope function Fx₀(t) shown in Fig. 9(B) in accordance with the modification characteristic
shown in Fig. 8(A).
[0059] The value of global envelope function W(t) shown in Fig. 9(A) at time
a is W(a) = 0 and is sufficiently smaller than the value of order x₀ of interest. As
shown in Fig. 8(B), value Fx₀(a) of x₀th-order envelope function Fx₀(t) at time
a is completely attenuated and is zero. Similarly, since value W(c) of the global envelope
function time
c is sufficiently smaller than the value of order x₀, value Fx₀(c) of the modified
envelope function is also zero, as shown in Fig. 8(D). Even at time
b when global envelope function W(t) has a maximum value, its value W(b) is larger
than the value of order x₀. Therefore, value Fx₀(b) of the modified envelope function
is not attenuated and is 1, as shown in Fig. 8(C). Value W(d) of the global envelope
function at time
d is slightly smaller than the value of order x₀. For this reason, order x₀ is located
in the region of the attenuation curve of f(x-W(t)) shown in Fig. 8(A). The modified
envelope function value is value Fx₀(d) between 0 and 1 in accordance with the characteristic
of attenuation curve f(x-W(t)), as shown in Fig. 8(E).
[0060] In practice, envelope modification device 14 performs modifications for all data
values of global envelope function W(t) in the form of waveform data supplied from
envelope generator 12. As a result, envelope function Fx₀(t) in the form of waveform
data shown in Fig. 9(B) is calculated.
[0061] Envelope functions of higher orders than order x₀ are attenuated as compared with
the x₀th-order envelope function. As a result, an effect similar to a low-pass filter
can be obtained.
[0062] Envelope modification device 14 can be arranged in various ways. For example, envelope
modification device 14 comprises a subtracter for calculating a difference between
the instantaneous value of the global envelope function output from envelope generator
12 and the value of the order from harmonic data memory 10, and a memory addressed
in response to output data from the subtracter to store waveform data of the modified
envelope function. Alternatively, if f(x-W(t)) in Fig. 8(A) can be calculated, a
calculation program is executed. For example, the value of order
x and the instantaneous value of global envelope function W(t) are compared. If the
value of order
x is smaller than the instantaneous value of the envelope function, the modified envelope
function value serves as a constant. However, if the value of order
x is larger than the instantaneous value, instantaneous value W(t) is used to calculate
f(x-W(t)). The sign of f(x-W(t)) is determined. If value f(x-W(t)) is positive, the
result serves as the modified envelope function value. Otherwise, zero serves as the
modified envelope function value.
[0063] A modification characteristic for the global envelope function/envelope functions
of the respective orders is not limited to the one shown in Fig. 8(A).
[0064] For example, in the range of x ≦ W(t) in Fig. 8(A), function Fx(t) is perfectly flat
but may be almost flat. The position of x = W(t) is the attenuation start point associated
with the cutoff point. However, x = W(t) + K (where K is a constant) may be the attenuation
start point. Alternatively, cx = W(t) (where
c is a constant) may be the attenuation start point. In the former case, (x-K) can
be regarded as the value of the order. In the latter case, cx can be regarded as the
value of the order.
[0065] An operation of envelope modification device 14 shown in Fig. 2 will be described
when waveform data for envelopes of the respective orders for obtaining an effect
similar to the high-pass filter is generated.
[0066] In this case, envelope modification device 14 performs the following modifications
to generate envelopes of the respective orders:
(j) If x > W(t), then Fx(t) = 1
(k) If x ≦ W(t), then Fx(t) = f(x-W(t))
(if f(x-W(t)) < 0, then Fx(t) = 0) where x is the order (corresponding harmonic data), W(t) is the global envelope function
(output from envelope generator 12), and Fx(t) is the converted envelope function
(output from envelope modification device 14). A substitution of x - W(t) into u yields the following conditions for f(u):
(ℓ) If u = 0, then f(u) = 1
(m) If u < 0, then fʹ(u) > 0
In addition, if f(u) = 1 is established for u > 0, the result coincides with Fx(t)
= 1 for x > W(t). This f(u) determines the modification characteristic with the envelope
function of a given order derived from the global envelope function.
[0067] If the value of order
x is larger than the value of global envelope function W(t), function f(u) is set to
be 1. However, if the value of order
x is smaller than the value of global envelope function W(t), the gradient of function
F(u) is positive. An example of such a modification characteristic is shown in Fig.
10(A). Difference
u is plotted along the abscissa and obtained by subtracting the value of global envelope
function W(t) from the value of order
x. In general, global envelope function W(t) is changed as a function of time
t. Therefore, if specific order x₀ is given, a value obtained by subtracting the value
W(t) from order x₀ is also changed as a function of time and is moved along the u-axis
in Fig. 10(A). The value of each f(u), i.e., value Fx₀(t
i) of the x₀th-order envelope function at each time t
i is also changed. The value of Fx₀(t
i) is not attenuated in the range of x₀ ≧ W(t). However, the value of Fx₀(t
i) is greatly attenuated in the range of x₀ < W(t) when the difference between x₀ and
W(t) is increased.
[0068] Assume that global envelope function W(t) shown in Fig. 10(B) is supplied from global
envelope memory 3 through envelope generator 12. Specific order x₀ has a dotted level.
In this case, envelope modification device 14 generates x₀th-order envelope function
Fx₀(t) shown in Fig. 10(C) in accordance with the modification characteristic shown
in Fig. 10(A).
[0069] In order to readily understand the modification values of the x₀th-order envelope
function which correspond to several values of global envelope function W(t) shown
in Fig. 10(B) are written. For example, Fx₀(d) is the value of the x₀th-order envelope
function at time
d. As is apparent from Fig. 10(B), W(d) is slightly larger than x₀ at time
d. In other words, the value of
u is negative. The point on f(u) at the position of
u in Fig. 10(A) is calculated. The obtained point represents Fx₀(d). Other points can
be obtained in the same manner as described above.
[0070] In practice, envelope modification device 14 performs modifications for all data
values of global envelope function W(t) in the form of waveform data supplied from
envelope generator 12. As a result, envelope function Fx₀(t) in the form of waveform
data shown in Fig. 10(C) is calculated for the x₀th order.
[0071] It is apparent from the above description that envelope functions having orders smaller
than the x₀th order are attenuated as compared with the x₀th-order envelope function.
As a result, an effect similar to a high-pass filter can be obtained.
[0072] Envelope modification device 14 can be arranged in various ways. For example, envelope
modification device 14 comprises a subtracter for calculating a difference between
the instantaneous value of the global envelope function output from envelope generator
12 and the value of the order from harmonic data memory 10, and a memory addressed
in response to output data from the subtracter to store waveform data of the modified
envelope function. Alternatively, if f(x-W(t)) in condition (k) can be calculated,
a calculation program is executed. For example, the value of order
x and the instantaneous value of global envelope function W(t) are compared. If the
value of order
x is larger than the instantaneous value of the envelope function, the modified envelope
function value serves as a constant. However, if the value of order
x is smaller than the instantaneous value, instantaneous value W(t) is used to calculate
f(x-W(t)). The sign of f(x-W(t)) is determined. If value f(x-W(t)) is positive, the
result serves as the modified envelope function value. Otherwise, zero serves as the
modified envelope function value.
[0073] A modification characteristic for the global envelope function/envelope functions
of the respective orders is not limited to the one shown in Fig. 10(A).
[0074] For example, in the range of u > 0, i.e., x > W(t) in Fig. 10(A), function Fx(t)
is perfectly flat but may be almost flat. The position of u = 0, i.e., x = W(t) is
the attenuation start point associated with the cutoff point. However, x = W(t) +
K (where K is a constant) may be the attenuation start point. Alternatively, cx =
W(t) (where
c is a constant or cx is an increment function) may be the attenuation start point.
In the former case, (x-K) can be regarded as the value of the order. In the latter
case, cx can be regarded as the value of the order.
[0075] Envelope modification device 14 described above generates envelope functions in the
form of waveform data by using the global envelope functions in the form of waveform
data and the order data. At the same time, all values of the waveform data of the
global envelope are modified.
[0076] To the contrary, an arrangement shown in Fig. 11 modifies a global envelope function
expressed by a set of rate data and level data shown in Fig. 4 into envelope functions
of the respective orders. In other words, several points of global envelope function
W(t) are modified in accordance with modification characteristic F(u). These points
include peak or break points (i.e., points corresponding to W(a), W(b), W(c), W(d),
and W(e) in Fig. 12) on global envelope function W(t) and points (i.e., points corresponding
to W(t₁) and W(t₂)) in which the values of function W(t) coincide with the values
of order
x.
[0077] Envelope modification device 14A in Fig. 11 executes the following algorithm to obtain
a set of rate data and level data which express the x₀th-order envelope function in
accordance with the set of rate and level data which define the global envelope data.
[0078] ℓ (i) and r(i) are level and rate data of the ith step of the global envelope function,
and L(j) and R(j) represent level and rate data of the jth step of the x₀th-order
envelope function to be stored in envelope memory 14B for respective orders. In addition,
ℓ(old) represents the previous level of the point on the global envelope function.
The initial value of level ℓ(old) is zero, and L(0) is also zero. Both initial values
of
i and
j are 1.
(1) Level ℓ (i) and rate r(i) of the current step are read out from global envelope
memory 3.
(2) Whether condition ℓ(old) < x₀ < ℓ(i) or ℓ(old) > x₀ > ℓ(i) is established is determined
(that is, whether the value of order x₀ is present between the previous and current
values of the global envelope functions is determined). If this determination is established,
the flow advances to (3). Otherwise, the flow advances to (7).
(3) Let (1+R) be level L(j) of the x₀th-order envelope function (that is, the jth
level of the x₀th-order envelope function is obtained).
(4) A division (x₀-ℓ(old))/r(i) is calculated, and the quotient is given as t (e.g., time t₁ between point W(a) and the next point W(t₁) in Fig. 12(B) is calculated).
(5) A division (L(j) - L(j-1))/t is calculated, and the quotient is given as rate
R(j) (that is, the jth rate of the x₀th-order envelope function is calculated).
(6) The value of order x₀ is set in ℓ(old), and the count of j is incremented by one.
(7) A difference F(x₀ - ℓ(i)) is calculated, and let the difference be level L(j)
(that is, the jth level of the x₀th-order envelope function is obtained in accordance
with modification characteristic F(u) for obtaining a low-pass filter type resonance
effect).
(8) A division (ℓ(i) - ℓ(old))/r(i) is calculated and the quotient is given as t (e.g.,
time between point W(t₁) in Fig. 12(B) and the next point W(b) is calculated; see
step (4)).
(9) A division (L(j) - L(j-1))/t is calculated and the quotient is defined as the
jth rate R(j) of the X₀th-order envelope function.
(10) Set the value of ℓ(i) in ℓ(old), and both the values of i and j are incremented by one. If i < 5, the flow returns to step (1). However if i = 5
then the flow is ended.
[0079] By performing the above processing, sets of rate and level data {(L(1),R(1)), (L(2),R(2)),...}
which define the x₀th-order envelope function (Fig. 12(C)) are stored in envelope
memory 14B for the respective orders. The above algorithm is an example, and similar
envelope functions can be obtained by using other algorithms.
[0080] Envelope generator 14C has an arrangement similar to that of envelope generator 12
shown in Fig. 2. In response to key depression on keyboard 1 (Fig. 1), rate and level
data are read out from the first step from envelope memory 14B for the respective
orders. The envelope functions of the respective orders which are expressed by rate
and level data are sequentially changed into waveform data. The amplitudes of sine
wave data of the corresponding orders which are output from multiplier 8 are controlled
by multiplier 9 in accordance with the waveform data sequentially generated by envelope
generator 14C.
[0081] The above description has been made to clarify a low-pass filter type resonance effect
of modification characteristic F(u) executed in envelope modification device 14A shown
in Fig. 11.
[0082] Fig. 13 shows a modification obtained by partially modifying the circuit arrangement
in Fig. 11. Envelope modification device 14A cooperates with global envelope generator
14D to modify the global envelope function from global envelope memory 3 into envelope
functions of the respective orders expressed in the same form as that of the global
envelope function. Global envelope generator 14D calculates an instantaneous value
of the global envelope function and basically comprises an accumulator. After the
rate data is set by envelope modification device 14A, envelope generator 14D adds
rate data to the accumulated value every time a clock is supplied from envelope modification
device 14A. An accumulation result is output to envelope modification device 14A.
Envelope modification device 14A comprises a level coincidence detector for detecting
a coincidence between the accumulation result front global envelope generator 14D
and global envelope predetermined level data, and an order coincidence detector for
detecting a coincidence between the accumulation result and the order data. If the
coincidence is established, the accumulation result is modified in accordance with
modification characteristic F(u) to obtain level data of envelopes of the respective
orders (The arrangement required for modification itself is substantially the same
as the corresponding section in envelope modification device 14 shown in Fig. 2).
If a coincidence signal is output from the level coincidence detector, global envelope
generator 14D is reset in accordance with the rate data of the next envelope step.
In addition, in order to obtain time information, envelope modification device 14A
comprises a counter for counting an operation count of each envelope step in global
envelope generator 14D and a circuit for calculating rate data of the envelopes of
the respective orders in accordance with a difference between the level data and time
data as the contents of the counter.
[0083] For example, envelope modification device 14A reads out the rate and level data of
step 1 for global envelope function W(t) shown in Fig. 12(B) (corresponding to the
interval between time
a and time
b in Fig. 12(B)) from global envelope memory 3. The level data is set in the internal
level coincidence detector, and the rate data is set in global envelope generator
14D. Envelope modification device 14A supplies a clock signal to generator 14D to
allow an accumulation operation and increments the count of the internal counter by
one. At time t₁ the internal order coincidence detector detects a coincidence between
the global envelope function value (output from global envelope generator 14D) and
the value of order x₀. In this case, envelope modification device 14A modifies the
function value in accordance with modification characteristic F(u) shown in Fig. 12(A).
The modified result is assured as the level data of the first step of the x₀th-order
envelope function. A difference between this level data and the immediately preceding
step level data (in this case, no preceding step is present, and the previous level
data represents zero) is calculated. The difference is divided by the count of the
counter, i.e., the value representing the time of the first step of x₀th-order envelope
function Fx₀(t). The quotient is assured as the rate data of the first step of the
x₀th-order envelope function. The counter is initialized for the second step of the
x₀th-order envelope function.
[0084] The operation of global envelope generator 14D is started again. The count of the
internal counter is incremented by one every time the accumulation cycle is completed.
When the count of the counter reaches a predetermined value (corresponding to time
b in Fig. 12(B)), the level coincidence circuit detects that the global envelope function
value as the accumulation result has reached the predetermined level. In the same
manner as described above, envelope modification device 14A calculates the level and
rate data of the second step of the x₀th-order envelope function. Thereafter, the
rate and level data of the next step are read out from global envelope memory 3 and
the above operations are repeated.
[0085] As a result, envelope control information (i.e., set of rate and level data) for
describing the x₀th-order envelope function shown in Fig. 12(C) are obtained. The
control information is temporarily stored in envelope memory 14B for the respective
orders.
[0086] Envelope generator 14C has the same arrangement as that of envelope generator 12C
of Fig. 11. In response to key depression on keyboard 1 (Fig. 1), rate and level data
are read out from the first step from envelope memory 14B for respective orders. The
envelope functions of the respective orders expressed by the rate and level data
are sequentially changed into waveform data.
[0087] In this manner, the envelopes of the respective orders expressed by the rate and
level data can be derived from the global envelope expressed by the rate and level
data in Fig. 13.
[0088] The above arrangement may be changed to obtain a high-pass filter type resonance
effect or a band-pass filter type resonance effect in place of the low-pass filter
type resonance effect. In this case, the circuit can be properly designed with reference
to Fig. 7, and Fig. 11, 12 or 13 to set the rate and level data which represent the
x₀th-order envelope function.
[0089] The resonance value R need not be a constant but be a variable which can be set by
the user. If the resonance value can be changed in real time, a performance effect
can be further improved.
[0090] An arrangement for performing real time resonance value changes can be obtained
by adding to the arrangement of Fig. 11 or 13 a multiplier, arranged between envelope
generator 14C and multiplier 9, for multiplying resonance depth coefficient R/R0 (where
R0 is the reference resonance depth which is reflected in the data stored in the envelope
memory 14B for the respective orders, and R is the resonance value designated by the
user) with the output from envelope generator 14C, a selector (its selection output
is input to multiplier 9) for selecting an output from the additional multiplier or
a direct output from envelope generator 14C, and a comparator for controlling selection
of the selector. This comparator compares the output from envelope generator 14C with
data of a level (e.g., level corresponding to F(u) = 1 in Fig. 12(A)) for switching
the output from envelope generator 14C. An output from this comparator is supplied
to the selection control input of the selector.
[0091] An operation of envelope modification device 14A shown in Fig. 11 will be described
when a low-pass filter type resonance effect is to be realized.
[0092] If low-pass filter type modification characteristic F(u) satisfying conditions (f)
to (i) is provided to envelope modification device 14A shown in Fig. 11, the following
algorithm is executed to obtain the x₀th-order envelope function expressed by the
sets of level and rate data.
(1) Level ℓ(i) and rate r(i) of the current step i are read out from global envelope memory 3.
(2) A function F(x₀ - ℓ(i)) is calculated, and the result is set as level L(i) of
step i of the x₀th-order envelope function.
(3) A division (ℓ(i) - ℓ(i-1))/r(i) is calculated, and the quotient is set as time
t of step i.
(4) A division (L(i) - L(i-1))/t is calculated, and the quotient is set as rate R(i)
of step i of the x₀th-order envelope function.
(5) Step number i is incremented by one. If i < 5, then the flow returns to step (1). However if i
= 5, then the flow is ended.
[0093] Similarly, an arrangement for obtaining a high-pass filter type resonance effect
by using envelope modification device 14A in Fig. 11 will be described below.
[0094] In order to assign high-pass filter type modification characteristic F(u) satisfying
conditions (j) to (m) to envelope modification device 14A in Fig. 11, the same algorithm
as the algorithm consisting of steps (1) to (5) described with reference to the low-pass
filter type resonance effect is performed to obtain the x₀th-order envelope function
expressed by sets of rate and level data (however, the algorithm in this case is different
from the that of steps (1) to (5) in that F(x-ℓ(i)) is calculated to obtain level
L(i) of each step of the x₀th-order envelope function).
[0095] In each arrangement described above, the filter characteristic is obtained by using
as a parameter difference
u between the value of order
x and global envelope function value W(t). The present invention can be easily modified
to perform modifications for performing a filter effect having several pass or stop
bands.
[0096] A very simple modification characteristic will be described below.
[0097] In this arrangement, only level data of the global envelope function expressed by
sets of rate and level data are modified. That is, when level data of each step of
the global envelope function is represented by LEVEL, the following modification is
performed:
LEVEL → F(X,LEVEL)
The right-hand side F(x,LEVEL) represents the level of the step corresponding to the
xth-order envelope function.
[0098] For example, F(x,LEVEL) is given as follows:
F(x,LEVEL) = 100[1 - {1 - (LEVEL/100)}x] ...(1)
In this case, modified level F(x,LEVEL) is changed in accordance with the values of
order
x as follows:
(A) 0th Order (x = 0)
[0099] In this case, level F(x.LEVEL) is given as follows regardless of the level of the
global envelope function:
F(0, LEVEL) = 100
[0100] For example, if the global envelope function is given as shown in Fig. 14(A), the
0th-order envelope function is given as shown in Fig. 14(B). The modified 0th-order
envelope function is used to control the envelopes of the 0th-order sine wave, i.e.,
the sine wave having the fundamental frequency.
(B) First Order (x = 1)
[0101] F(1,LEVEL) = LEVEL is given. That is, each level of the given global envelope function
is always equal to that of the first-order envelope function. The first-order envelope
function is the same as the global envelope function (Fig. 14(C)). The waveform data
of the first-order envelope function is used to control the envelope of the first-order
sine wave signal, i.e., the envelope of the sine wave signal having a frequency of
a second harmonic.
(C) Second Order (x = 2)
[0102] F(2,LEVEL) = 2LEVEL - 100 is given. The level of each step of the global envelope
function is doubled, and 100 is subtracted from the doubled value. The resultant difference
serves as the corresponding level of the second-order envelope function (Fig. 14(D)).
The second-order envelope function is applied to a sine wave having a frequency of
a second order, i.e., third harmonic.
[0103] Envelope functions of higher orders can be produced in the same manner as described
above. If the modification function given in equation (1) is used, the envelope function
is attenuated and its amplitude change is small when the order is increased.
[0104] Function 100[1 - {1 - (LEVEL/100}x] is an example. An arbitrary function may be selected,
such as a function having an amplitude which is greatly changed when the order is
increased.
[0105] The modification of only levels can be easily realized by envelope modification device
14D shown in Fig. 11. For example, the following algorithm can be used:
(1) Rate r(i) of step i from global envelope memory 3 is transferred to envelope memory 14B as rate R(i)
of step i of the xth-order envelope function.
(2) Level ℓ(i) of step i is read out from global envelope memory 3.
(3) Function F(x,ℓ(i)) is calculated, and the result is transferred to envelope memory
14b as level L(i) of step i of the xth-order envelope function.
(4) Step number i is incremented by one. If i < 5, then the flow returns to step (1). However, if i
= 5, the algorithm is ended.
[0106] The above level modification can be easily performed by envelope modification device
14 shown in Fig. 2. F(x,W(t)) for each W(t) from envelope generator 12 is calculated.
[0107] In the arrangement of Fig. 11, the rate modification in addition to the level modification
can be performed as follows:
LEVEL → F(x,LEVEL)
Rate → G(x,LEVEL)
G(x,RATE) is a rate value corresponding to the xth-order envelope function obtained
by modifying value RATE of the global envelope function in accordance with the value
of order
x.
[0108] Several arrangements have been described in detail above. The present invention is
not limited to these. Various changes, modifications, and improvements may be made.
In the above embodiment, a plurality (n) of envelope-controlled sine wave generators
15-1 to 15-n are used. However, hardware of a sine generator is not limited if it
functionally provides a plurality of sine waves.
[0109] For example, at least some of envelope-controlled sine wave generators 15-1 to 15-n
can be realized by TDM (time-division multiplexing).
[0110] Another embodiment of the present invention will be described with reference to Fig.
15.
[0111] Referring to Fig. 15, the envelope-controlled sine wave generator section is divided
into two groups: envelope-controlled sine wave generators 15-1 to 15-n as the first
group and envelope-controlled sine wave generators 15ʹ-1 to 15ʹ-m as the second group.
Envelope-controlled sine wave generators 15-1 to 15-n and 15ʹ-1 to 15ʹ-m are connected
to keyboard 1 as a performance input device and data input device 2 for inputting
various data. At data input device 2, the user can specify independent harmonic data
to the respective groups of envelope-controlled sine wave generators. Sine wave generators
15-1 to 15-n and 15ʹ-1 to 15ʹ-m can generate different sine waves having independent
frequencies on the basis of prestored harmonic data upon key depression at keyboard
1. The feature of this embodiment lies in that the first and second groups constituted
by the corresponding envelope-controlled sine wave generators are coupled to the
corresponding global envelope memories. More specifically, envelope-controlled sine
wave generators 15-1 to 15-n of the first group are coupled to first global envelope
memory 3-1, and envelope-controlled sine wave generators 15ʹ-1 to 15ʹ-m of the second
group are coupled to second global envelope memory 3-2. First and second global envelope
memories 3-1 and 3-2 respectively store first and second global envelope functions
W1(t) and W2(t) which are independently set at data input device 2. First global envelope
function W1(t) is converted to
n envelope functions of
n orders determined by the assigned harmonic data (order) in envelope-controlled sine
wave generators 15-1 to 15-n belonging to the first group. Second global envelope
function W2(t) is modified into
m envelope functions determined by the assigned harmonic data in envelope-controlled
sine wave generators 15ʹ-1 to 15ʹ-m belonging to the second group. The modified envelope
functions of the respective orders are used to control the envelopes of the sine wave
signals of the corresponding orders in envelope-controlled sine wave generators 15-1
to 15-n.
[0112] In this embodiment, if one envelope (i.e. the global envelope function) is given
for sine wave signals of one group, a plurality of envelope functions, i.e., envelope
functions of sine wave signals belonging to this group can be obtained based on the
given function. The load imposed on the user who produces the envelopes can be greatly
reduced. In addition, according to this embodiment, since independent global envelope
functions are set in units of groups, musical tones with a variety of tone colors
can be obtained as compared with the arrangement in which a common global envelope
is given for all sine waves without dividing a set of sine waves into a plurality
of groups.
[0113] Referring back to the arrangement of Fig. 15, envelope-controlled sine wave data
from envelope-controlled sine wave generators 15-1 to 15-n and 15ʹ-1 to 15ʹ-m are
added by adders 16-1 and 16-2, respectively. The sum signals (musical tone signals)
are converted into analog signals by D/A converter 17. The analog signals are produced
outside through amplifier 18 and loudspeaker 19. Although adders 16-1 and 16-2 are
represented as separate units, only one adder can be used to add output data from
envelope-controlled sine wave generators 15-1 to 15-n and 15ʹ-1 to 15ʹ-m.
[0114] The detailed arrangement of each envelopecontrolled sine wave generator is the same
as that in Fig. 2, 11 or 13.
[0115] The independent first and second global envelope functions can be arbitrarily set
by the user. Independency and flexibility between the global envelope functions are
reflected in envelope functions (i.e., the envelope functions for the sine waves of
the first group and the envelope functions for the sine waves of the second group)
converted by envelope modification device 14 or 14A. Therefore, a variety of finally
produced musical tone signals can be achieved.
[0116] In the above embodiment, the global envelope functions can be input and set by the
user in units of groups. The envelope functions of the first group applied to the
sine waves of the first group are independent of the envelope functions of the second
group applied to the sine waves of the second group. For example, if the global envelope
function shown in Fig. 14(A) is a global envelope function of the first group and
a global envelope function entirely different therefrom is a global envelope function
of the second group, envelope functions of orders (e.g., 0th, 1st, and 2nd orders)
obtained on the basis of the global envelope function of the second group are obviously
different from those shown in Figs. 14(B), 14(C), and 14(D).
[0117] Independency between the envelope function groups can be obtained by other means,
as has been described above. As compared with other means, the arrangement of this
embodiment is more advantageous due to the following reason. In this embodiment, a
total number of combinations of the global envelope functions of the first and second
groups is greatly increased upon selection by the user. In order to obtain the same
effect by other means, e.g., a means for producing different global envelope functions
from a given one global envelope function, a large number of modification algorithms
and large hardware are required.
[0118] In the arrangement of Fig. 15, envelope-controlled sine wave generators 15-1 to 15-n
of the first group and envelope-controlled sine wave generators 15ʹ-1 to 15ʹ-m of
the second group are fixedly illustrated. However the user can arbitrarily determine
which generators belong to the first or second group. Some generators may be added
or omitted easily within the scope of the present invention.
[0119] In the above embodiment, the envelope-controlled sine wave generators are divided
into two groups but may be divided into three or more groups. In an extreme case,
a given group may use one sine wave.
[0120] In the above embodiment, the frequency of the generated sine wave is a fundamental
frequency or its harmonic due to the relationship with harmonic data. However, the
arrangement is not limited to this. For example, a sine wave having a frequency obtained
by detuning the sine wave frequency of the first group may be used as the sine wave
of the second group. A technique for generating a sine wave having a detuned frequency
is known to those skilled in the art. For example, in phase angle generator 6 in Fig.
2, the repetitive accumulation value of the accumulator is offset by a predetermined
number of sent.
[0121] In the above embodiment, the plurality of envelope-controlled sine wave generators
15-1 to 15-n and 15ʹ-1 to 15ʹ-m are used. However, hardware is not limited if a plurality
of sine waves can be functionally generated. A sine wave generator may be arranged
in accordance with a time division multiplexing.
[0122] According to the present invention as described above in detail, a common envelope
function is provided for the component wave signals of a plurality of orders. The
common envelope function is modified by the envelope modifying means into envelope
functions of the respective orders. The envelopes of the component wave signals are
controlled in accordance with modified envelope functions. Therefore, the user need
not prepare all envelopes for the component wave signals. Much labor can be advantageously
reduced to produce musical tones.
[0123] Furthermore, the global envelope setting means is arranged to give at least one global
envelope function. The plurality of component waves to be produced by the component
wave generating means are divided into at least the first and second groups. The envelope
functions for controlling the component waves of the respective orders belonging to
the first group are obtained by modifying the global envelope function by the first
envelope modifying means, and the envelope functions for controlling the component
waves of the respective orders belonging to the second group are obtained by modifying
another global envelope function by the second envelope modifying means. Therefore,
the user need set only a limited number of envelopes, thus improving operability for
producing musical tones. In addition, since the envelope functions for controlling
the component waves of the first group can be independent of the envelope functions
for controlling the component waves of the second group, musical tone with high-quality
musical tones can be produced.
[0124] The present invention is exemplified by the particular embodiment described above
in detail. However, the present invention is not limited to these embodiments, and
various changes and modifications may be made within the spirit and scope of the invention.