Nippon Telegraph and Telephone Corporation

Japan Tobacco Inc.

Masahiro Fukui

Yusuke Hiwasaki

Noboru Harada

Takehiro Moriya

Yutaka Kamamoto

Kazunori Kobayashi

Kimitaka Tsutsumi

Shoichi Koyama

Shigeaki Sasaki

Noriyoshi Kamado

Akihiro Saito

Kazuhiro Yoshimura

Hidehisa Tokita

Tetsuya Nakamura

Akira Nakagawa

Shoichiro Saito

Shunsuke Tawada

Sachiko Kurihara

Hiroyuki Uesugi

Hiroko Murai

Two speaker units are arranged on the right side from the center of a seat; two speaker units are arranged on the left side from the center of the seat; one of the two speaker units arranged on the right side is arranged at a position closer to the right ear of a user seated on the seat as compared with the other one of the two speaker units arranged on the right side; one of the two speaker units arranged on the left side is arranged at a position closer to the left ear of the user seated on the seat as compared with the other one of the two speaker units arranged on the left side; acoustic signals obtained on the basis of a reproduction target are emitted from the two speaker units arranged on the right side to be opposite in phase to each other; the acoustic signals obtained on the basis of the reproduction target are emitted from the two speaker units arranged on the left side to be opposite in phase to each other; and the acoustic signals are emitted from two speaker units arranged on the positions closer to the ears not to be opposite in phase to each other.

Speaker system

A sound system includes: a control system that generates a control signal for erasing noise from a signal of the noise in a place close to a head of a user who uses a seat; a silencing speaker system that is installed at the place close to the head of the user who uses the seat and includes M speaker units each emitting a sound based on the control signal; and an emission suppression unit including at least a sound absorbing material that easily absorbs only a sound having a frequency greater than or equal to a predetermined value and configured to make it difficult for the sound having the frequency greater than or equal to the predetermined value emitted from the silencing speaker units to be emitted to a place other than an ear of the user. The m-th silencing speaker unit is arranged so that a sound emitted from the m-th silencing speaker unit in the m-th silencing user direction is silenced at a place other than a place close to the head of the user who uses the seat due to coming around of a sound emitted from the m-th silencing speaker unit in a direction opposite to the m-th silencing user direction.

Sound system

Provided is a technique for selecting a cancellation filter coefficient that can stably cancel noise for a user using a seat of an aircraft, an automobile, or the like. A cancellation filter coefficient selection apparatus includes: a recording unit configured to record cancellation filter coefficients; a seat position acquisition unit configured to acquire a position of a seat used by a user; and a cancellation filter coefficient selection unit configured to, from among the cancellation filter coefficients recorded in the recording unit, select a cancellation filter coefficient corresponding to the position of the seat as a cancellation filter coefficient to be used in filtering for generating a cancellation signal for cancelling noise at a position where quiet is desired, based on a reference signal output by a reference microphone configured to collect noise in a predetermined space. The reference microphone and a speaker for emitting sound based on the cancellation signal are installed on the seat, and positions of the reference microphone and the speaker in the predetermined space change accompanying movement of the seat.

Cancel filter coefficient selecting apparatus, cancel filter coefficient selecting method, and program

A sound system, for a user using a seat of an aircraft, an automobile, or the like, that reproduces sound inaudible to users around, without using earphones or headphones, is provided. A sound system for a user using a seat of an aircraft includes: a reproduction apparatus including an n-th reproduction unit (n=1, . . . , N) that outputs a (2n−1)-th sound signal that is a sound signal obtained based on a subject to be reproduced, and a 2n-th sound signal that is a sound signal with opposite phase to phase of the (2n−1)-th sound signal, N being an integer equal to or larger than one; and a speaker system including an n-th speaker unit pair (n=1, . . . , N) including a speaker unit that emits sound based on the (2n−1)-th sound signal (hereinafter, referred to as the positive speaker unit) and a speaker unit that emits sound based on the 2n-th sound signal (hereinafter, referred to as the negative speaker unit), the speaker system being installed at a place close to a head of the user using the seat.

A technology is provided that reduces noise heard when a user sits in a seat of an aircraft, without using earphones or headphones. A sound system includes: a control system that generates a control signal for canceling noise in a place close to a head of a user using a seat of an aircraft, from a signal of the noise (noise signal); and a noise-cancellation speaker system including speaker units that emit sound based on the control signal (first noise-cancellation speaker unit, . . . , M-th noise-cancellation speaker unit), the noise-cancellation speaker system being installed at the place close to the head of the user using the seat, wherein assuming that a direction in which the m-th noise-cancellation speaker unit faces the user is an m-th noise-cancellation user direction, the m-th noise-cancellation speaker unit is disposed such that sound emitted from the m-th noise-cancellation speaker unit in the m-th noise-cancellation user direction is canceled in a place other than the place close to the head of the user using the seat, due to bending around of sound emitted from the m-th noise-cancellation speaker unit in an opposite direction to the m-th noise-cancellation user direction.

The speaker array includes a first speaker, a second speaker, and a local sound emission structure. The first transmission portionand the second transmission portionare arranged in such a manner that the distance between the center position of the first transmission portionand the center position of the second transmission portionis smaller than the distance between the center position of the first speakerand the center position of the second speaker, in order to generate sound sources that are arranged at an interval narrower than the interval between the first speakerand the second speaker

Speaker array

The number of conversational tests needed for the evaluation of acoustic quality of the ICC system is reduced. An evaluation value conversion deviceevaluates the quality of communication between a near-end acoustic regionand a far-end acoustic regioninside a vehicle for which a plurality of acoustic regions are predetermined. A voice signal picked up by a microphone Mdisposed in the far-end acoustic regionis emitted from a speaker Sdisposed in the near-end acoustic region. An objective evaluation value acquisition unitacquires a first evaluation value by treating a voice signal obtained by combining a voice signal resulting from a first voice signal being emitted from a sound source in a seat belonging to the far-end acoustic region, picked up by the microphone M, and emitted from the speaker Swith a voice signal arriving at a seat belonging to the near-end acoustic regionas a result of the first voice signal being transmitted through the space inside the vehicle as an evaluation target sound, and treating the first voice signal as a reference sound. An evaluation value reuse unitacquires the first evaluation value as an evaluation value of communication between a seat belonging to the near-end acoustic regionand a seat belonging to the far-end acoustic region

Evaluation method, evaluation apparatus, and program

Provided is an echo cancellation apparatus capable of calculating an acoustic coupling amount with high accuracy regardless of the magnitude of the near-end speaker component and without using a double talk detector. The echo cancellation apparatus cancels an echo included in a sound pickup signal picked up by a microphone placed at a near-end and includes an acoustic coupling amount calculation unit that updates and calculates an acoustic coupling amount estimated value of a component of a reproduction signal, which is a signal picked up by a microphone placed at a far-end included in the sound pickup signal, such that an update amount is decreased the greater a magnitude of a component other than an echo component is in the sound pickup signal; a gain calculation unit that calculates a gain coefficient on the basis of the acoustic coupling amount estimated value; and an integration unit that integrates the gain coefficient with the sound pickup signal and generates an echo cancellation signal.

Echo cancellation device, echo cancellation method, and program

Provided is a technology for generating an elimination filter coefficient for suppressing degradation of noise elimination performance. An elimination filter coefficient generation method for inputting a reference signal output from a reference microphone for collecting noise and an error signal output from an error microphone for collecting sound at a position that needs to be silent, and generating an elimination filter coefficient used for filtering for generating an elimination signal for eliminating noise at the position that needs to be silent from the reference signal includes: a route filtering step for generating a filtered reference signal from the reference signal by filtering using a route filter coefficient indicating acoustic characteristics of a route from a speaker for emitting sound based on the elimination signal to the error microphone; a first noise signal generation step for generating a predetermined signal as a first noise signal; a noise signal addition step for generating an added reference signal from the filtered reference signal and the first noise signal; and an elimination filter coefficient generation step for generating the elimination filter coefficient from the error signal and the added reference signal.

Cancel filter coefficient generation method, cancel filter coefficient generation apparatus, and program

An object is to provide a sound collection apparatus capable of collecting a sound with a higher SN rate than before through use of a reflected sound. The sound collection apparatus is installed in a vehicle. The vehicle includes a seat for a passenger to sit on, and a reflective structure that reflects a sound emitted by a passenger sitting in the seat. The sound collection apparatus includes a first microphone arranged at a position where a direct sound that is a sound emitted by the passenger is readily collected, and a second microphone arranged at a position where a reflected sound that is a sound emitted by the passenger and reflected by the reflective structure is readily collected.

Sound collection apparatus

In encoding, a frequency-domain sample sequence derived from an acoustic signal is divided by a weighted envelope and is then divided by a gain, the result obtained is quantized, and each sample is variable-length encoded. The error between the sample before quantization and the sample after quantization is quantized with information saved in this variable-length encoding. This quantization is performed under a rule that specifies, according to the number of saved bits, samples whose errors are to be quantized. In decoding, variable-length codes in an input sequence of codes are decoded to obtain a frequency-domain sample sequence; an error signal is further decoded under a rule that depends on the number of bits of the variable-length codes; and from the obtained sample sequence, the original sample sequence is obtained according to supplementary information.

Encoding method, decoding method, encoder, decoder, program, and recording medium

A normalization value calculatorcalculates a normalization value that is representative of a predetermined number of input samples. A normalization value quantizerquantizes the normalization value to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value. An quantization-candidate calculatorsubtracts a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each of the samples to obtain a difference value and, when the difference value is positive and the value of each of the samples is positive, sets the difference value as an quantization candidate corresponding to the sample. When the difference value is positive and the value of each of the samples is negative, the quantization-candidate calculatorreverses the sign of the difference value and setting the sign-reversed value as an quantization candidate corresponding to the sample. When the difference value is not positive, the quantization-candidate calculatorsets 0 as an quantization candidate corresponding to the sample. A vector quantizerjointly vector-quantizes a plurality of quantization candidates corresponding to a plurality of samples to obtain a vector quantization index.

Coding method, decoding method, apparatus, program, and recording medium

A frequency-domain sample interval corresponding to a time-domain pitch period L corresponding to a time-domain pitch period code of an audio signal in a given time period is obtained as a converted interval T, a frequency-domain pitch period T is chosen from among candidates including the converted interval Tand integer multiples U&#xd7;Tof the converted interval T, and a frequency-domain pitch period code indicating how many times the frequency-domain pitch period T is greater than the converted interval Tis obtained. The frequency-domain pitch period code is output so that a decoding side can identify the frequency-domain pitch period T.

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Tokyo, Japan

Masahiro Fukui