JP4303026B2 - Acoustic signal processing apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an acoustic signal processing apparatus and method for compensating for lack of bass range and enhancing bass feeling. More specifically, the present invention relates to a method for enhancing bass feeling by adding overtones related to bass components, such as a small speaker. In particular, the present invention relates to a technique suitable for using a device that tends to lack bass.
[0002]
[Prior art]
In general, it is well known that reproduction of a low sound range is difficult with a small speaker. In order to solve this problem, when the harmonics are played instead of the bass that is difficult to reproduce, the virtual pitch effect is used to produce an audible bass even though the harmonics are being played. It has been conventionally known that it can be improved.
[0003]
Here, the term “overtone” has the following two definitions. In the first definition, “overtone” means a sound component other than a fundamental tone (sound at a fundamental frequency) in a musical tone or an original tone, and has a frequency that is a natural number multiple of the fundamental tone.
[0004]
In the second definition, “overtone” means a sound having a frequency that is a natural number multiple of a certain target sound.
[0005]
Hereinafter, in the present specification, “overtones” according to these two definitions are not distinguished and are simply referred to as “overtones”. A harmonic having a frequency n times (n is a natural number) the frequency of the fundamental tone or the original tone is referred to as the nth harmonic.
[0006]
Hereinafter, a conventional acoustic signal processing apparatus (two types) will be described with reference to FIGS.
[0007]
First, FIG. 8A is a block diagram of a conventional first acoustic signal processing apparatus. As shown in FIG. 8A, the signal input from the input terminal 1 is divided into two systems, and the input signal of the first system is input to one input unit of the adder 7.
[0008]
The input signal of the second system is input to the low pass filter 5. The low-pass filter 5 extracts only the bass component from the input signal according to a predetermined cut-off characteristic, and outputs it to the overtone generation means 4.
[0009]
The harmonic overtone generation unit 4 generates a signal (overtone) having a frequency component that is an integral multiple of the low frequency range component extracted by the low pass filter 5. The overtone generated by the overtone generation means 4 is input to the other input unit of the adder 7.
[0010]
The adder 7 adds the signals input to one input unit and the other input unit, and outputs the result to the output terminal 2.
[0011]
There are various methods for generating overtones. Of these, the zero cross method will be described with reference to FIG.
[0012]
Here, consider an example of generating a harmonic over a sine wave as shown in FIG.
[0013]
The zero cross point is a point at which the signal changes from positive to negative or from negative to positive. For example, in FIG. 9A, the zero cross points from negative to positive are point P1, point P2, and point P3.
[0014]
In the case of generating the second overtone, in the section (section P1-P2, section P2-P3) from the negative-to-positive zero-cross point to the next negative-to-positive zero-cross point, The waveform may be compressed to 1/2 and replayed twice. As a result, the processed signal becomes a signal having a frequency twice as shown in FIG. 9B.
[0015]
In general, when n is a natural number, the nth overtone is generated by compressing the original waveform to 1 / n in the time-axis direction and repeatedly reproducing it n times in the same zero cross point section.
[0016]
In the first conventional acoustic signal processing apparatus shown in FIG. 8A, when a composite sound (a sound having a plurality of frequency components such as chords) is input, frequency components other than harmonics to be generated are generated. The sound quality is deteriorated due to distortion.
[0017]
Next, a conventional second acoustic signal processing apparatus that improves this point will be described with reference to FIG. In the figure, the same components as those in FIG.
[0018]
The main point of the example shown in FIG. 8B is that the composite sound is divided into a plurality of frequency bands, and overtone generation is performed for each component belonging to each frequency band.
[0019]
That is, in FIG. 8B, a band dividing unit 6 is newly provided with respect to FIG. 8A, and the band dividing unit 6 includes a plurality of band pass filters 5a having different frequency bands. 5b,..., 5c, and divides the bass component of the input signal into signals for each frequency band.
[0020]
The divided signals are input to overtone generation means 4a, 4b,..., 4c provided for each frequency band, and overtone generation is performed individually. The output signals of the plurality of overtone generating means 4a, 4b,..., 4c are added by the adder 7a and input to one input unit of the adder 7b.
[0021]
As shown in FIG. 8B, when band division is performed, overtone generation is performed for a signal of one frequency component in principle for one frequency band even when a composite sound is input. The generation of distortion components is suppressed.
[0022]
[Problems to be solved by the invention]
As described above, the method of dividing the band has an advantage that it is possible to suppress deterioration in sound quality when inputting a composite sound. However, in the conventional technology, there is no consideration regarding how harmonics should be generated for each frequency band component divided.
[0023]
However, as is clarified by the present research by the present inventors, as will be described in detail later, if this harmonic structure is not performed well, the sound quality is deteriorated, or the improvement effect of the low tone is obtained. Not enough. In other words, the configuration of FIG. 8B has not yet reached a satisfactory level.
[0024]
Accordingly, an object of the present invention is to provide an overtone generation technique that has a high bass improvement effect and a low distortion feeling in an acoustic signal processing device that performs band division processing.
[0025]
[Means for Solving the Problems]
The acoustic signal processing device according to the first invention is an input acoustic signal. Of each frequency component included in the Band dividing means for dividing; Overtones of frequency components that belong to each divided frequency band can be reproduced in a band that can be reproduced by the speaker. Overtone generating means for generating and generated Overtone And a synthesis means for synthesizing the input acoustic signal, The harmonic generation means further includes: First frequency band Belongs to frequency The highest order among the orders of one or more harmonics generated from the component is the first frequency band Lower Second frequency band Of the order of one or more harmonics generated from the frequency components belonging to frequency band Belongs to frequency The highest order among the orders of one or more harmonics generated from the component is the lowest frequency band Belongs to frequency On condition that it is less than the highest order of one or more harmonics generated from the component Generate overtones .
[0026]
In this configuration, by imposing a certain condition in the overtone generation in the overtone generation means, Does not generate overtone components outside the reproducible band of the assumed speaker, Inappropriate overtone generation can be eliminated, and preferable overtones can be generated. As a result, the sense of bass can be improved while suppressing the sense of distortion.
[0027]
In the acoustic signal processing device according to the second invention, the harmonic overtone generating means is further, highest frequency band Belongs to frequency The condition that the smallest order among one or more harmonics generated from the component is less than the smallest order among the orders of one or more harmonics generated from the frequency component belonging to the lowest frequency band Generate overtones with .
[0030]
With this configuration, First, by not generating an overtone component with a frequency that is too high, it is possible to prevent the reproduced sound from shifting toward the middle and high frequencies, and to prevent unnatural changes in the timbre. Second, overloading of the speaker can be prevented by preventing the generation of a harmonic component having a frequency component that is too low.
[0038]
In the acoustic signal processing device according to the third invention, Overtone generation means Furthermore, a condition that only a single-order harmonic component is generated in each of the divided frequency bands. Generate overtones with .
[0039]
With this configuration, it is possible to improve bass feeling with a small processing load.
[0040]
First 4 In the acoustic signal processing device according to the invention, The single order is the minimum reachable order (the minimum order that reaches the reproducible band of the assumed speaker) .
[0041]
With this configuration, it is possible to concentrate the bass component on the low frequency side of the assumed reproducible band of the speaker, and to effectively improve the bass feeling.
[0042]
In the acoustic signal processing device according to the fifth invention, the single order is divided. each The frequencies of the overtone components generated from the frequency components belonging to each of the frequency bands are set so as not to overlap each other.
[0043]
With this configuration, the order of the low-frequency component is easily continued, and a reproduced sound with a natural and less distorted feeling can be obtained.
[0044]
In the sound processing apparatus according to the sixth invention, Generated The amplitude of the harmonic component is set so as to decrease as the frequency of the harmonic component increases.
[0045]
With this configuration, it is possible to prevent the reproduced sound from shifting to the middle / high sound side in terms of hearing.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
(Comparative example)
Prior to the description of the overtone generation method in each embodiment of the present invention, a comparative example of overtone generation will be described below. In conclusion, according to this comparative example, there is a problem particularly when the basic tone is a low tone and the low-order harmonics are below the reproducible band of the speaker.
[0047]
In the present specification, it is assumed that the reproducible band of the speaker is 150 Hz or more. Further, as shown in FIG. 2A, band division for generating overtones is set at 25 Hz intervals. Then, the second to fourth overtones are generated in each frequency band that is divided. However, harmonics less than 150 Hz are not generated.
[0048]
Therefore, in this comparative example,
For the frequency band A (25 to 50 Hz), only the fourth overtone is generated.
For the frequency band B (50 to 75 Hz), the third overtone and the fourth overtone are generated.
Second to fourth overtones are generated for frequency band C (75 to 100 Hz), frequency band D (100 to 125 Hz), and frequency band E (125 to 150 Hz).
[0049]
In this comparative example, let us consider a case where a musical tone having a fundamental tone of 40 Hz is input. In this case, as shown in FIG. 2B, the processing band includes three frequency components, that is, the fundamental tone (40 Hz), second harmonic (80 Hz), and third harmonic (120 Hz) of the musical tone.
[0050]
These three frequency components are separated by a band division process. The 40 Hz component is in the frequency band A, the 80 Hz component is in the frequency band C, and the 120 Hz component is in the frequency band. D And overtones are generated for each frequency band.
[0051]
As a result, it becomes as shown in FIG. That is,
A harmonic of 160 Hz is generated from the fundamental tone (40 Hz) belonging to the frequency band A (25 to 50 Hz).
Overtones of 160 Hz, 240 Hz, and 320 Hz are generated from the second overtone (80 Hz) belonging to the frequency band C (75 to 100 Hz).
frequency band D (100-125 Hz), harmonics of 240 Hz, 360 Hz, and 480 Hz are generated from the third harmonic (120 Hz).
[0052]
Therefore, in the comparative example, overtone components of 160 Hz, 240 Hz, 320 Hz, 360 Hz, and 480 Hz are generated as a whole.
[0053]
Here, the harmonics to be generated are arranged as follows with the order based on the fundamental tone 40 Hz of the original signal.
4th harmonic (160 Hz), 6th harmonic (240 Hz), 8th harmonic (320 Hz), 9th harmonic (360 Hz), 12th harmonic (480 Hz)
[0054]
From the above, it can be seen that the fifth overtone, the seventh overtone, etc. are missing and are not generated. In addition, higher harmonics such as the ninth overtone and the twelfth overtone that do not contribute to the improvement of the low tone are generated.
[0055]
If such a harmonic overtone having such a complicated structure is generated, not only the low tone feeling is improved, but also the reproduced sound is felt as if it is shifted toward the middle and high frequencies, or a unique timbre change occurs.
[0056]
As described above, in the acoustic signal processing device, some guidelines are necessary for the configuration of the generated overtones for improving the low-pitched sound. Based on the above findings, the present inventors have completed the technique proposed this time. In addition, about the evaluation of each following embodiment and a comparative example, it puts together at the end and is explained in full detail.
[0057]
Hereinafter, each embodiment of the present invention will be described.
(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an acoustic signal processing apparatus according to Embodiment 1 of the present invention.
[0058]
Hereinafter, in Embodiments 1 and 2, as in the comparative example, the reproducible band of the speaker is set to 150 Hz or more, and a harmonic component is generated for a low sound range of 150 Hz or less. And about a harmonic component, a fixed frequency range shall be 150-280 Hz. Of course, these numerical values are merely examples, and it goes without saying that they can be changed as appropriate.
[0059]
Of the components shown in FIG. 1A, the input terminal 1 is for inputting an input signal.
[0060]
The band dividing means 6 extracts a bass component for generating overtones from the input signal and divides it into signals for each frequency band. Here, the band dividing means 6 is configured by providing a plurality of band pass filters 5a, 5b,..., 5c having different pass bands in parallel.
[0061]
The harmonic overtone generation means 4a, 4b,..., 4c provided for each frequency band generate overtones for the output signals of the band pass filters 5a, 5b,.
[0062]
The adder 7a adds the output signals of the overtone generating means 4a, 4b,..., 4c. The delay device 3 delays the input signal by the same time as the delay associated with the overtone generation process.
[0063]
The adder 7 b corresponds to a synthesis unit, adds the output signal of the delay unit 3 and the output signal of the adder 7 a, and outputs an acoustic signal from the output terminal 2 via the high-pass filter 8.
[0064]
The high-pass filter 8 is provided to remove a low-frequency component below the reproducible band of the speaker and prevent overload of the speaker.
[0065]
The high-pass filter 8 can be provided before or after the delay device 3. Further, although the overload prevention function is lost, the high-pass filter 8 can be omitted.
[0066]
In order to make this acoustic signal processing apparatus compatible with stereo input, it is only necessary to prepare two circuits of FIG. 1A separately for the left channel and the right channel.
[0067]
Alternatively, as shown in FIG. 7, after the left and right inputs are added and monauralized, a process relating to overtone generation may be performed, and a process of distributing the left and right again may be performed.
[0068]
When configured as shown in FIG. 7, the circuit scale can be reduced as compared with the case where the circuit of FIG. 1A is provided independently for each of the left and right channels. Here, since the bass component is often included in the same phase in each channel, the sound quality hardly deteriorates even when configured as shown in FIG.
[0069]
In this embodiment, as in the comparative example, the division characteristics in the band dividing unit 6 are set as shown in FIG. In the example of FIG. 2A, the frequency band from 25 Hz to 150 Hz is divided by the frequency band of 25 Hz.
[0070]
Alternatively, as shown in FIG. 2C, the lowest sound range (50 Hz or less) may have a low-pass characteristic.
[0071]
Now, the overtone generating means 4a, 4b,..., 4c provided for each frequency band have the circuit configuration shown in FIG.
[0072]
The harmonic overtone generating means 4a, 4b,..., 4c are provided with harmonic overtone component generating means 9a, 9b,..., 9c that generate M harmonics from the nth harmonic to the (n + M−1) harmonic over the input signal, Multipliers 10a, 10b,..., 10c provided in the subsequent stage multiply the outputs of these overtone component generating means 9a, 9b,. Then, the adder 7c adds the outputs of the multipliers 10a, 10b,.
[0073]
That is, for each signal divided by frequency band, as shown in FIG. 3, M harmonics are generated continuously from the lowest nth harmonic that falls within the reproducible band of the speaker. As the coefficient sequence a1 to aM for adjusting the amplitude level of each overtone, a coefficient sequence whose values are attenuated as it becomes higher is used. For example, as a coefficient sequence a1 to aM, a geometric sequence (a1, a1 × r, a1 × r × r,...) Having a common ratio r can be used. The common ratio r is, for example, 0.3.
[0074]
In FIG. 1 (a), generation condition setting means 20 inputs generation condition information from the outside, and sets constant conditions for harmonic generation in each of the harmonic generation means 4a, 4b,. This generation condition information is information related to the above-described orders n, n + M-1, coefficient a1, common ratio r, and the like of the harmonic component.
[0075]
Here, in the example of FIG. 1A, the generation condition setting unit 20 can change the constant condition in each of the overtone generation units 4a, 4b,.
[0076]
However, when only one fixed condition is used, the generation condition setting means 20 is omitted, and the circuit configurations of the harmonic overtone generation means 4a, 4b,..., 4c are fixedly configured so as to meet desired constant conditions. You can also In this case, as shown in FIG. 1B, it is not always necessary to provide the harmonic component generating means for all of the nth harmonic to the (n + M−1) th harmonic. That is, for the harmonics of the order not used, the harmonic generation means may be omitted and the circuit configuration may be simplified.
[0077]
Next, the overtone generation method, which is the subject of the present invention, will be described in detail. First, the minimum arrival order is defined. The minimum reaching order is the minimum order that reaches the reproducible band (150 Hz or more in the present specification) of the loudspeaker with respect to overtone generation performed on the signal components in each divided frequency band.
[0078]
For example, in FIG. 2A, the minimum reaching order is
Third order in frequency band B (50-75 Hz)
Secondary in frequency band C (75-100 Hz)
Secondary in frequency band D (100-125 Hz)
Secondary in frequency band E (125-150 Hz)
It is.
[0079]
However, for the frequency band A (25 to 50 Hz), the minimum arrival order of the frequency 25 to 30 Hz is sixth, the minimum arrival order of the frequency 30 to 37.5 Hz is fifth, and the frequency 37.5 Hz to 50 Hz. The minimum reaching order is the fourth order.
[0080]
Thus, depending on the division characteristics, there are a plurality of candidates for the minimum arrival order, and the minimum arrival order may not be uniquely determined. In such a case, any candidate among these candidates may be set as the minimum arrival order. Here, the minimum arrival order for the frequency band A is the fourth order.
[0081]
Using the minimum reach order described above, harmonics are generated as follows. In the first embodiment, in each frequency band, a plurality of consecutive harmonics of the order including only the harmonics of the minimum reaching order or including the harmonics of the minimum reaching order are generated. At this time, the lower frequency band is configured so that the number of overtones to be generated increases.
[0082]
For example, the following pattern 1 and pattern 2 can be considered.
[0083]
(Pattern 1)
In the frequency band A, fourth, fifth and sixth overtones are generated.
In the frequency band B, third and fourth overtones are generated.
In the frequency bands C, D, and E, the second overtone is generated.
[0084]
(Pattern 2)
In the frequency band A, fourth, fifth, sixth and seventh overtones are generated.
In the frequency band B, third and fourth overtones are generated.
In the frequency band C, second and third overtones are generated.
In the frequency bands D and E, the second overtone is generated.
[0085]
According to such a harmonic generation method, even when a musical sound having a low fundamental frequency is input, the generated harmonic does not have an irregular configuration, and a natural harmonic can be generated. Hereinafter, the reason will be described.
[0086]
Assuming that the original signal is a musical sound, the original signal includes a fundamental tone and harmonics of the frequency n times (n = 2, 3,...). The fundamental tone can also be regarded as a harmonic of n = 1. With respect to this original signal, the harmonic overtone generation means generates overtones of m times (m = 2, 3,...), And considering the fundamental tone of the original sound as a reference, overtones having a frequency of n × m times are generated. .
[0087]
At this time, if too high harmonics are generated, it is felt that the pitch is shifted toward the middle and high pitches. Therefore, there is an upper limit value for the order n × m. That is, the larger the value of n, the smaller the value of m can be. In other words, many harmonics can be added up to a relatively high frequency in the lowest frequency band, such as frequency band A, but low harmonics in a relatively high frequency band, such as frequency band E. It can only be taken.
[0088]
If the value of the order n × m is a prime number, harmonics can be generated only from n = 1, that is, only from the fundamental tone of the original signal. For example, the fifth and seventh harmonics of the fundamental tone of the original signal can be generated only from the fundamental tone of the original signal. Therefore, it is better to increase the number of overtones generated in the lower range, and this makes it difficult to form an distorted overtone string.
[0089]
In the above example, consider a signal sequence having a fundamental tone (40 Hz) as an original signal and containing harmonic components of 80 Hz and 120 Hz in the original signal.
[0090]
In pattern 1 shown in FIG.
Overtones of 160 Hz, 200 Hz, and 240 Hz are generated from the 40 Hz component belonging to the frequency band A.
A harmonic of 160 Hz is generated from the 80 Hz component belonging to the frequency band C.
frequency band D A harmonic of 240 Hz is generated from the 120 Hz component belonging to.
[0091]
In pattern 2 shown in FIG.
Overtones of 160 Hz, 200 Hz, 240 Hz, and 280 Hz are generated from the 40 Hz component belonging to the frequency band A.
Overtones of 160 Hz and 240 Hz are generated from the 80 Hz component belonging to the frequency band C.
frequency band D A harmonic of 240 Hz is generated from the 120 Hz component belonging to.
[0092]
Here, in pattern 1, overtones are generated in the range of 4th to 6th overtones with respect to the fundamental tone of the original signal without loss of order.
[0093]
In pattern 2, overtones are generated in the range of fourth to seventh overtones with respect to the fundamental tone of the original signal without loss of order.
[0094]
Moreover, an overtone that is higher than the ninth overtone is not generated. Therefore, it is less likely that the pitch is shifted toward the middle and high pitches, or a unique timbre change does not occur, and an output signal with improved bass feel can be obtained.
[0095]
In this way, according to this configuration method, even when a musical sound having a low fundamental frequency that includes a plurality of frequency components in the processing band is input, the harmonics having a natural structure having a continuous order in the reproducible band of the speaker. Can be generated. As a result, it is possible to suppress deterioration in sound quality when a musical sound having a low fundamental frequency is input. Further, by reducing the number of overtones generated in the high frequency band, the circuit scale required for the generation can be reduced.
[0096]
(Embodiment 2)
In the second embodiment, another configuration method is implemented for overtone generation in the same circuit as in the first embodiment (see FIGS. 1A, 1B, and 7). In short, the configuration method according to the second embodiment is a method of generating only one minimum attainment order or harmonic overtone according to this in each frequency band.
[0097]
That is, in the frequency band shown in FIG. 2A, for example, the following pattern 3 and pattern 4 can be considered.
[0098]
(Pattern 3)
In the frequency band A, the fourth overtone is generated.
In the frequency band B, a third overtone is generated.
In the frequency bands C, D, and E, the second overtone is generated.
[0099]
(Pattern 4)
In the frequency band A, the fifth overtone is generated.
In the frequency band B, a third overtone is generated.
In the frequency bands C, D, and E, the second overtone is generated.
[0100]
In the same example as in the first embodiment, as shown in FIG. 2 (b), a signal sequence in which the fundamental signal is a musical tone having a fundamental frequency of 40 Hz and the harmonic component of 80 Hz and 120 Hz is included in the original signal is considered.
[0101]
In pattern 3 shown in FIG.
A harmonic of 160 Hz is generated from the 40 Hz component belonging to the frequency band A.
A harmonic of 160 Hz is generated from the 80 Hz component belonging to the frequency band C.
frequency band D A harmonic of 240 Hz is generated from the 120 Hz component belonging to.
[0102]
In pattern 4 shown in FIG.
A harmonic of 200 Hz is generated from the 40 Hz component belonging to the frequency band A.
A harmonic of 160 Hz is generated from the 80 Hz component belonging to the frequency band C.
frequency band D A harmonic of 240 Hz is generated from the 120 Hz component belonging to.
[0103]
For pattern 3, since the fifth overtone (200 Hz) with respect to the fundamental tone of the original signal is not generated, the sense of bass is slightly inferior. The pattern 4 is improved from the pattern 3 because it is continuously generated from the fourth overtone to the sixth overtone.
[0104]
Since the configuration method shown in the second embodiment generates only one overtone per frequency band, it is slightly inferior in terms of improving the bass feeling compared to the first embodiment. However, on the other hand, the amount of calculation can be reduced and the circuit scale can be reduced. In addition, distortion that occurs when generating overtones is reduced, and clear sound quality is achieved.
[0105]
In the first and second embodiments, the case where the reproducible band of the speaker is 150 Hz or more has been described. Needless to say, the present invention is not limited to the reproducible area of the speaker, and various small speakers having different reproducible bands. It is applicable to.
[0106]
(Evaluation)
Since the present inventors evaluated the comparative example, pattern 1, and pattern 3 described above, the results are shown below.
[0107]
Although specific evaluation was not performed for pattern 2 and pattern 4, it was estimated that the same result as pattern 1 was obtained for pattern 2, and the same result as pattern 3 was obtained for pattern 4. It is estimated that
[0108]
As for evaluation, subjects A and B compare the processed sound that generated harmonics with the patterns 1 and 3 and the comparative example, and the original sound, and how much bass is improved, or whether or not there is a sense of distortion, Examined.
[0109]
The following three sound sources were used as sources.
(Source 1) Artist: Noriyuki Sugawara, Song name: SPY, Evaluation section: 30 seconds from the start of the song
(Source 2) Artist: Cindy Rover, Song title: HEY NOW, Evaluation section: 30 seconds from the start of the song
(Source 3) Artist: Diana King, Song title: SHY GUY, Evaluation section: 30 seconds after 40 seconds
[0110]
Subject A
Bass feeling improvement effect ○: considerably improved, △: slightly improved, ×: almost no improvement
[0111]
Sense of distortion ○: Almost none, △: Slightly felt, ×: Slightly felt
[0112]
[0113]
Subject B
Bass feeling improvement effect ○: considerably improved, △: slightly improved, ×: almost no improvement
[0114]
Sense of distortion ○: Almost none, △: Slightly felt, ×: Slightly felt
[0115]
[0116]
(Discussion)
Regardless of the subject, it is considered that the pattern 1 that is highly effective in improving bass feeling and evaluated as having little distortion feeling is the most excellent.
[0117]
On the other hand, it was found that the comparative example had a strong sense of distortion and was not practical. This distortion not only invalidated the bass improvement effect, but also shifted the sound of low music instruments in the source to the middle and high frequencies, and caused a unique timbre change.
[0118]
In pattern 3, the low tone was inferior to pattern 1, but the sound quality was clearer than pattern 1.
[0119]
Generally speaking, both pattern 1 and pattern 3 were superior to the comparative example in terms of both the low-pitched sound enhancement effect and the low distortion.
[0120]
【The invention's effect】
According to the present invention, the number of overtones generated by the harmonic overtone generation unit with the higher frequency band is determined to be equal to or less than the number of overtones generated by the overtone generation unit with the lower frequency band, so that the amount of overtones is continuously reduced. Can be generated in a concentrated manner at a low frequency within the reproducible band of the speaker.
[0121]
According to the present invention, it is possible to optimize the configuration of the generated harmonic overtone when the band division processing is introduced so that the sound quality is less deteriorated and a low tone is felt.
[Brief description of the drawings]
FIG. 1A is a block diagram of an acoustic signal processing apparatus according to Embodiments 1 and 2 of the present invention.
(B) Block diagram of the same harmonic generation means
FIG. 2A is an exemplary diagram of the same band division characteristics.
(B) Example of the same band division characteristics
(C) Example of the same band division characteristics
FIG. 3 is a graph showing an example of the amplitude configuration of the same harmonic generation
FIG. 4 is an explanatory diagram of harmonic overtone generation in the comparative example.
FIG. 5A is a diagram for explaining overtone generation in the first embodiment (pattern 1).
(B) Overtone generation explanatory diagram (Pattern 2) in the first embodiment
6A is an explanatory diagram of harmonic overtone generation in the second embodiment (pattern 3). FIG.
(B) Overtone generation explanatory diagram (pattern 4) in the second embodiment
FIG. 7 is a block diagram of an acoustic signal processing apparatus for the stereo signal.
FIG. 8A is a block diagram of a first conventional acoustic signal processing apparatus.
(B) Block diagram of a second conventional acoustic signal processing device
FIG. 9A is an explanatory diagram of a conventional overtone generation principle.
(B) Conventional harmonic generation principle explanatory diagram
[Explanation of symbols]
1, 1a, 1b, 11 input terminals
2, 2a, 2b, 12 Output terminals
3, 3a, 3b delay device
4a-4c harmonic overtone generating means
5a-5c band pass filter
6 Band division means
7a-7e Adder
8, 8a, 8b High-pass filter
9a-9c Overtone component generating means
10a-10c Level adjustment means
20 Generation condition setting means

Claims (7)

Band dividing means for dividing a low frequency component lower than a band that can be reproduced by a speaker among frequency components included in an input acoustic signal into a plurality of frequency bands;
Harmonic overtone generating means for generating overtones of frequency components belonging to each of the divided frequency bands in a band that can be reproduced by a speaker ;
A synthesis means for synthesizing the generated overtone and the input acoustic signal;
The harmonic overtone generation means further includes:
One biggest order of the following numbers, generated from the frequency components belonging to the lower than the first frequency band a second frequency band of one or more harmonics are generated from the frequency components belonging to a first frequency band Less than the largest of the above harmonic orders,
Further, the highest order among the orders of one or more harmonics generated from the frequency component belonging to the highest frequency band is the highest among the orders of one or more harmonics generated from the frequency component belonging to the lowest frequency band. Less than a large order,
To generate overtones,
An acoustic signal processing device. The harmonic overtone generation means further includes:
The highest smallest degree among the one or more harmonics are generated from the frequency components belonging to the frequency band, of the order of one or more harmonics are generated from the frequency components belonging to the lowest frequency band smallest in order below is there,
The acoustic signal processing apparatus according to claim 1 , wherein overtones are generated under the condition: The harmonic overtone generation means further includes:
3. The acoustic signal processing apparatus according to claim 2 , wherein harmonics are generated under a condition that only a single-order harmonic component is generated in each of the divided frequency bands.   The acoustic signal processing apparatus according to claim 3, wherein the single order is a minimum attainment order (a minimum order to reach a reproducible band of an assumed speaker).   The acoustic signal processing device according to claim 3, wherein the single order is set so that frequencies of overtone components generated from frequency components belonging to each of the divided frequency bands do not overlap each other. The acoustic signal processing device according to claim 1, wherein the amplitude of the generated harmonic component is set to decrease as the frequency of the harmonic component increases. A band dividing step of dividing a low frequency component lower than a band that can be reproduced by a speaker among frequency components included in the input acoustic signal into a plurality of frequency bands;
A harmonic overtone generating step of generating overtones of frequency components belonging to each of the divided frequency bands in a band reproducible by a speaker ;
A synthesis step of synthesizing the generated overtone and the input acoustic signal;
The harmonic generation step further includes:
One biggest order of the following numbers, generated from the frequency components belonging to the lower than the first frequency band a second frequency band of one or more harmonics are generated from the frequency components belonging to a first frequency band Less than the largest of the above harmonic orders,
Further, the highest order among the orders of one or more harmonics generated from the frequency component belonging to the highest frequency band is the highest among the orders of one or more harmonics generated from the frequency component belonging to the lowest frequency band. Less than a large order,
An acoustic signal processing method characterized by generating overtones under the condition :