Nippon Telegraph and Telephone Corporation

Kenta Imaizumi

Kimitaka Tsutsumi

Atsushi Nakadaira

Yoichi Haneda

Takashi Sato

Provided is a sound image localization device capable of flexibly controlling directivity with a short calculation time. A sound image localization device that reflects, on a reflector, a sound signal radiated from a speaker arrayarranged with a plurality of speakers SPto SPon a straight line to localize a sound image includes an expansion coefficient calculation unitconfigured to analytically calculate expansion coefficients by performing a spherical harmonic function expansion on a window function representing desired directivity, a filter coefficient generation unitconfigured to convert the expansion coefficients into filter coefficients corresponding to each of the speakers SPto SP, and a speaker drive unitconfigured to generate a speaker drive signal for driving each of the speakers SPto SPby convolving the filter coefficients in a voice signal.

Sound image localization device, sound image localization method, and program

A sound field generation apparatus includes: a first modulation unit modulating an ultrasonic wave signal according to a prescribed modulation system; a second modulation unit modulating the ultrasonic wave signal according to a modulation system different from the modulation system of the first modulation unit; a filter unit changing frequency characteristics of an audible range signal used in modulation of the second modulation unit; a first ultrasonic wave output unit outputting a first ultrasonic wave signal modulated by the first modulation unit; and a second ultrasonic wave output unit outputting a second ultrasonic wave signal modulated by the second modulation unit, wherein the filter unit is set to have filter characteristics to cancel a first audible sound reproduced by the first ultrasonic wave signal with a second audible sound reproduced by the second ultrasonic wave signal at a control point provided outside the sound field.

Sound field generator, sound field generation method, and program

Provided is a sound image localizing device, a sound image localizing method, and a program that enable a virtual speaker to reproduce sound in a wide frequency band with high sound quality. A sound image localizing deviceincludes a directivity control filter design unitthat computes a directivity control filter from a desired directional characteristic, a filter coefficient correction unitthat corrects the directivity control filter computed by the directivity control filter design unit, and a convolution operation unitthat computes an output acoustic signal by performing convolution of an input acoustic signal and the directivity control filter corrected by the filter coefficient correction unit. Filters that respectively correspond to speakers constituting a speaker array are computed by the directivity control filter design unitand the filter coefficient correction unit, an acoustic beam is generated using directivity control by the speaker array, and the acoustic beam is caused to be reflected from a wall surface or a ceiling to generate a virtual sound source.

A signal processing deviceincludes an expansion coefficient calculation unitthat, from an outward sound field to be reproduced, calculates a spherical harmonics expansion coefficient for reproducing the sound field; an expansion coefficient conversion unitthat converts the calculated spherical harmonics expansion coefficient into a weight factor for superposition of multipole sources; a filter coefficient calculation unitthat, from the weight factor, calculates a filter coefficient corresponding to each speaker included in a multipole speaker array, the speaker providing output outwardly; and a convolution operation unitthat convolves the filter coefficient corresponding to each speaker into an input acoustic signal to calculate an output acoustic signal for each speaker.

Signal processing apparatus, signal processing method, and signal processing program

The scale of an apparatus that reproduces a sound field is reduced. A speaker array 1 includes a plurality of speakers arranged at intersections of a first plurality of virtual lines arranged parallel to each other at equal intervals and a second plurality of virtual lines that are perpendicular to the first plurality of virtual lines and are arranged parallel to each other at equal intervals, wherein multipoles of a given order are superimposed using the plurality of speakers to realize wave field synthesis.

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Musashino, Japan

Kenta Imaizumi