# US 2023/0276191 A1 · Method for generating stereophonic sound

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- Number: US 2023/0276191 A1
- Document ID: US20230276191A1
- Status: Published application
- Kind: A1
- Application number: 18/016,840
- Filed: 2021-08-05
- Published: 2023-08-31
- Earliest claimed: 2020-08-07
- Assignees: Next Sound Inc.
- Applicants: Next Sound Inc.
- Inventors: Masahito TOBISAWA
- Web page: https://patentgrep.com/patent/US20230276191A1

## CPC

- H04S 1/005: {For headphones}
- H04S 7/307: {Frequency adjustment, e.g. tone control (H04S7/301 takes precedence)}
- G10K 15/02: Synthesis of acoustic waves (synthesis of speech G10L13/00)
- H04R 5/04: Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)}
- H04S 1/007: {in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02)}
- H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
- H04S 2420/01: Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
- H04S: STEREOPHONIC SYSTEMS
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

Provided is a method for generating stereophonic sound. According to one embodiment of the present invention, a phase angle relative to an original sound is controlled by focusing on a rearward sense of localization, which is difficult to express, and using a plurality of delay devices (delay machines) to change the time, phase, and direction thereof. Thereby provided is a technology having the purpose of improving a subjective evaluation in a psychological space by using a rearwardly-localized sound source to emphasize and effectively simulate there actually being a sound source toward the rear.

## Claims

### Claim 1

A method for generating a stereophonic sound by performing phase delay control, the method comprising:
a step of obtaining an acoustic signal having a base note on a right ear side and an acoustic signal having a base note on a left ear side; and
a step of determining to control a phase of either one of the acoustic signal obtained on the right ear side and having a note or the acoustic signal obtained on the left ear side and having a note, wherein
the acoustic signal having the base note to be delayed is further subjected to
a step of generating an acoustic signal that is derived from a frequency of the acoustic signal having the base note and that has a first phase shift generated by performing a first phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from the acoustic signal having the base note and that has a second phase shift generated by performing a second phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a note a perfect fourth above the base note and that has a third phase shift generated by performing a third phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from the frequency of the acoustic signal having the note the perfect fourth above the base note, and that has a fourth phase shift generated by performing a fourth phase delay process on the acoustic signal having the base note, and
a step of synthesizing the acoustic signal obtained and having the base note, the acoustic signal having the first phase shift, the acoustic signal having the second phase shift, the acoustic signal having the third phase shift, and the acoustic signal having the fourth phase shift.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising a step of synthesizing an overtone of the note to be delayed.

### Claim 3

A method for generating a stereophonic sound by a phase delay control device including four areas, the method comprising:
a step of obtaining an acoustic signal having a base note on a right ear side and an acoustic signal having a base note on a left ear side; and
a step of determining to control a phase of either one of the acoustic signal obtained on the right ear side and having a note or the acoustic signal obtained on the left ear side and having a note, wherein
the acoustic signal having the base note to be delayed is further subjected to
a step of generating an acoustic signal that is derived from a frequency of the acoustic signal having the base note and that has a first phase shift generated by performing 180 degree phase delay control and 0 degree phase delay control, the 180 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 1 wavelength, the 0 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to 2 wavelengths,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a second note a perfect fourth above the base note and that has a second phase shift generated by performing −90 degree phase delay control and 0 degree phase delay control, the −90 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to ¾ wavelengths on the acoustic signal having the base note, the 0 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 1.5 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a third note a perfect fifth below the second note and that has a third phase shift generated by performing −135 degree phase delay control and 90 degree phase delay control, the −135 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 9/8 wavelengths on the acoustic signal having the base note, the 90 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to 18/8 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a fourth note a perfect fourth above the third note and that has a fourth phase shift generated by performing −60 degree phase delay control and 60 degree phase delay control, the −60 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to ⅚ wavelengths on the acoustic signal having the base note, the 60 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 10/6 wavelengths on the acoustic signal having the base note, and
a step of synthesizing the acoustic signal having the base note, the acoustic signal having the first phase shift, the acoustic signal having the second phase shift, the acoustic signal having the third phase shift, and the acoustic signal having the fourth phase shift.

### Claim 4 (depends on 1)

A device comprising means for performing the respective steps of claim 1.

### Claim 5 (depends on 1)

A program for performing the method of claim 1.

### Claim 6

A method for generating a stereophonic sound by a phase delay control device including eight areas, the method comprising:
a step of obtaining an acoustic signal having a base note on a right ear side and an acoustic signal having a base note on a left ear side; and
a step of determining to control a phase of either one of the acoustic signal obtained on the right ear side and having a note or the acoustic signal obtained on the left ear side and having a note, wherein
the acoustic signal having the base note to be delayed is further subjected to
a step of generating an acoustic signal that is derived from a frequency of the acoustic signal having the base note and that has a first phase shift generated by performing 180 degree phase delay control and 0 degree phase delay control, the 180 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 1 wavelength, the 0 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to 2 wavelengths,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a second note a perfect fourth above the acoustic signal having the base note and that has a second phase shift generated by performing −90 degree phase delay control and 0 degree phase delay control, the −90 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to ¾ wavelengths on the acoustic signal having the base note, the 0 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 1.5 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a third note a perfect fifth below the second note and that has a third phase shift generated by performing −135 degree phase delay control and 90 degree phase delay control, the −135 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 9/8 wavelengths on the acoustic signal having the base note, the 90 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to 18/8 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a fourth note a perfect fourth above the third note and that has a fourth phase shift generated by performing −60 degree phase delay control and 60 degree phase delay control, the −60 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to ⅚ wavelengths on the acoustic signal having the base note, the 60 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 10/6 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a fifth note a major second above the base note and that has a fifth phase shift generated by performing 140 degree phase delay control and −80 degree phase delay control, the 140 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 8/9 wavelengths on the acoustic signal having the base note, the −80 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to 16/9 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a sixth note a perfect fourth above the fifth note and that has a sixth phase shift generated by performing −120 degree phase delay control and −60 degree phase delay control, the −120 degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to ⅔ wavelengths on the acoustic signal having the base note, the −60 degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to 4/3 wavelengths on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a seventh note a perfect fifth below the sixth note and that has a seventh phase shift generated by performing slightly-more-than-180-degree phase delay control and slightly-more-than-0-degree phase delay control, the slightly-more-than-180-degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to a wavelength slightly longer than 1 wavelength on the acoustic signal having the base note equal to a first note, the slightly-more-than-0-degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to a wavelength slightly longer than 2 wavelengths on the acoustic signal having the base note equal to the first note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having an eighth note a perfect fourth above the seventh note and that has an eighth phase shift generated by performing slightly-less-than-−90-degree phase delay control and slightly-more-than-0-degree phase delay control, the slightly-less-than-−90-degree phase delay control being produced by a positive phase component obtained by performing a delay process for a delay corresponding to a wavelength slightly longer than ¾ wavelengths on the acoustic signal having the base note equal to the second note, the slightly-more-than-0-degree phase delay control being produced by a negative phase component obtained by performing a delay process for a delay corresponding to a wavelength slightly longer than 1.5 wavelengths on the acoustic signal having the base note equal to the second note, and
a step of synthesizing the acoustic signal having the base note, the acoustic signal having the first phase shift, the acoustic signal having the second phase shift, the acoustic signal having the third phase shift, the acoustic signal having the fourth phase shift, the acoustic signal having the fifth phase shift, the acoustic signal having the sixth phase shift, the acoustic signal having the seventh phase shift, and the acoustic signal having the eighth phase shift.

### Claim 7

A method for generating a stereophonic sound by performing phase delay control, the method comprising:
a step of obtaining an acoustic signal having a base note on a right ear side and an acoustic signal having a base note on a left ear side; and
a step of determining to control a phase of either one of the acoustic signal obtained on the right ear side and having a note or the acoustic signal obtained on the left ear side and having a note, wherein
a step of generating an acoustic signal that is derived from a frequency of the acoustic signal having the base note and that has a first phase shift generated by performing a first phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from the acoustic signal having the base note and that has a second phase shift generated by performing a second phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from a frequency of an acoustic signal having a note different from the base note and that has a third phase shift generated by performing a third phase delay process on the acoustic signal having the base note,
a step of generating an acoustic signal that is derived from the frequency of the acoustic signal having the note different from the base note and that has a fourth phase shift generated by performing a fourth phase delay process on the acoustic signal having the base note, and
a step of synthesizing the acoustic signal obtained and having the base note, the acoustic signal having the first phase shift, the acoustic signal having the second phase shift, the acoustic signal having the third phase shift, and the acoustic signal having the fourth phase shift
are further performed on the acoustic signal having the base note to be delayed.