Matsushita Electric Industrial Co., Ltd.

Honda Giken Kogyo Kabushiki Kaisha

Panasonic Corporation

Matsushita Denkisangyo Kabushiki Kaisha

Kenichi Terai

Hiroyuki Hashimoto

Isao Kakuhari

Yasutoshi Nakama

Toshio Inoue

Akira Takahashi

Hisashi Sano

Kazutaka Abe

Yoshio Nakamura

Tsuyoshi Yamashita

Tadashi Tamura

Shuji Saiki

Katsuhiko Hayashi

Koichi Hashimoto

Masayuki Misaki

Ko Mizuno

Hiroyuki Kotani

Yasuhito Watanabe

Kousaku Murata

Shuichi Obata

Nobuaki Minakuchi

Kazue Satoh

Gempo Ito

Katsuaki Satoh

Takamasa Yoshikawa

Koji Watanabe

Hideki Ishinaga

Michiko Ogawa

Toshihiko Ohashi

Hiroshi Hamanaka

Toshiaki Tabuchi

Toshiyuki Ueda

Yoichi Kumura

Hironari Ogata

Chie Yano

Takahisa Hachuda

Masaharu Morita

A signal processing apparatus includes an input attribute determination section for determining an input attribute representing at least one of a type of an audio codec, a sampling frequency and a number of channels of an input signal; and an input signal processing section for processing the input signal. The input signal processing section determines whether the input attribute has been changed based on a determination result provided by the input attribute determination section; and when a calculation remainder generated in the input signal processing section by the change in the input attribute, the input signal processing section assigns at least apart of the calculation remainder to processing of the input signal.

Signal processing apparatus

A wide frequency range signal from a test sound source is reproduced successively by a plurality of speakers, and the reproduced sound is detected by a plurality of microphones, after which the frequency characteristics are obtained at FFTs, while obtaining the frequency characteristics of the wide frequency range signal at an FFT. A high frequency range level is normalized with a low frequency range level, and a determination section compares the normalized value with a reference value stored in a reference value storage section to determine the number and positions of people in the sound field. The transfer functions between the speakers and the microphones are calculated at transfer function calculators, and impulse responses are obtained at IFFTs, after which a reverberation time calculator calculates the reverberation time based on the impulse responses. An audio signal is adjusted based on the results.

Sound field measurement device

A sound image control device filters transfer functions Hand Hindicating transfer characteristics of a sound from an acoustic transducer () to entrances to respective ear canals () and () as well as filtering transfer functions Hand Hfrom an acoustic transducer () to the entrances to the respective ear canals () and () and generates second transfer functions Hand Hindicating transfer characteristics of a sound to the entrances to the respective ear canals () and () from a target sound source () at a location different from the sound sources, the sound image control device being equipped with correction filters () and () that (i) store characteristic functions Eand Efor performing filtering operations on the first transfer functions H, H, H, and Hand (ii) generate the second transfer functions Hand Hfrom the first transfer functions H, H, H, and Husing such characteristic functions Eand E

Sound image control device and design tool therefor

A sound image control system which is able to concurrently perform sound image localization control for two persons is provided. The sound image control system controls a sound image localization position by reproducing an audio signal from a plurality of loudspeakers. The sound image control system includes at least four loudspeakers for reproducing the audio signal and a signal processing section. The signal processing section sets four points corresponding to both ears of two listeners as control points, and performs signal processing for the audio signal input into the plurality of loudspeakers so that two target sound source positions indicating sound image localization positions of the respective two listeners are set in the same direction with respect to the two listeners. The two target sound source positions are set so as to satisfy the following condition, T=T&#x2266;T&#x3c;T

Sound image control system

An active noise control system is capable of canceling out noise in the passenger compartment of a vehicle based on low-frequency road noise. The active noise control system has a feed-forward control unit for being supplied with reference signals highly correlated to noise from a noise source and generating a noise cancellation signal which is out of phase to noise in the passenger compartment of the vehicle, and a canceling sound generating unit disposed in the passenger compartment for generating a noise canceling sound in response to the noise cancellation signal from said feed-forward control unit. The active noise control system also has microphones for generating reference signals which are positioned respectively near the base of the front seat, near the center of a roof, and within a trunk compartment, i.e., respectively at vibrational antinodes of a primary or secondary acoustic normal mode of the passenger compartment in the longitudinal direction thereof. Output signals from the microphones are supplied as the reference signals.

Active noise control system

A sound-amplification apparatus comprises: an acoustic signal source for outputting an acoustic signal; an amplified sound source for receiving the acoustic signal from the acoustic signal source and radiating an amplified sound; a control sound source provided in a vicinity of the amplified sound source for radiating a control sound; and signal processing means for producing a control sound signal by controlling at least one of an amplitude and a phase of the acoustic signal from the acoustic signal source so that an acoustic space having a desired directionality is formed by interference between the amplified sound and the control sound, and providing the control sound signal to the control sound source.

Public addressing system

A first rectifying net, a rectifying grid and a second rectifying net are attached, as a rectifying part upstream of a duct through which air for cooling flows. A noise detection microphone detects noise within the duct. An error detection microphone is placed in the downstream side of the noise to detect error noise. An arithmetic circuit inputs a noise signal of the noise detection microphone, carries out an arithmetic of a transfer function so that an output signal of the error detection microphone becomes minimum, and outputs a control signal to a control sound source. The control sound source radiates a control sound having approximately the same sound pressure as and an opposite phase of the noise within the duct. Thus, the coherence between the noise in the upstream and downstream parts increases, thereby enhancing a sound-muffling effect.

A sound reproduction device of the present invention includes: a first loudspeaker; a second loudspeaker; a first loudspeaker drive section for driving the first and second loudspeakers, the first loudspeaker drive section drives the first and second loudspeakers at substantially the same phase in a first frequency band, and the first loudspeaker drive section drives the first and second loudspeakers at substantially inverse phase and substantially different amplitude levels in a second frequency band higher than the first frequency band.

Sound reproduction device

A digital AV signal processing apparatus includes a buffer for storing digital data input to the digital AV signal processing apparatus, and outputting the digital data as output digital data, a D/A converter for converting the output digital data to analog data, a voltage-controlled oscillator for generating a clock signal to control a conversion rate of the D/A converter, and a voltage-controlled oscillator controller for detecting a data amount of the digital data stored in the buffer, and controlling a frequency of the clock signal based on a deviation in the detected data amount from a first predetermined value and a time integral of the deviation value.

Digital AV signal processing apparatus

An active noise control system for reducing road noise of low frequency generated inside the cabin of a vehicle is provided. The active noise control system includes a noise detector, a signal generator for processing the input noise signal to generate a signal for producing noise canceling waves, a limiting amplifier having a specified threshold value for variably amplifying the processed signal so that the amplitude of output signal will not exceed the threshold value, and an electrical acoustic converter for producing noise canceling acoustic waves in accordance with the output signal.

A signal processing apparatus includes an input attribute determination section for determining an input attribute representing at least one of a type of an audio codec, a sampling frequency and a number of channels of an input signal; and an input signal processing section for processing the input signal. The input signal processing section determines whether the input attribute has been changed based on a determination result provided by the input attribute determination section; and when a calculation remainder generated in the input signal processing section by the change in the input attribute, the input signal processing section assigns at least a part of the calculation remainder to processing of the input signal.

A headphone system includes a headphone; and a signal processing circuit for outputting an acoustic signal to the headphone. The headphone includes a first speaker and a third speaker for a right ear of a listener, a second speaker and a fourth speaker for a left ear of the listener, and a support for supporting the first through fourth speakers so that the first and second speakers are located forward with respect to a vertical plane including a straight line connecting the hole of the right ear and the hole of the left ear of the listener, the second and fourth speakers are located rearward with respect to the vertical plane, and the first through fourth speakers are out of contact with the right ear and the left ear of the listener.

Headphone system

In an active noise control apparatus in which an audio signal and a noise control signal are mixed to thereby sound a loudspeaker inside a motor vehicle, a general-purpose audio head unit cannot conventionally be freely changed for the one already mounted on the motor vehicle. As a solution, an active noise control unit is provided with a buffer amplifier and a mixer. An audio signal amplified by a power amplifier in an audio head unit is adjusted in level by the buffer amplifier such that a level of an audio signal outputted after amplification by the first amplifier becomes substantially equal to a level of the audio signal outputted from the audio head unit. Then, at the mixer, a noise control signal outputted from an active noise controller is added to an audio signal outputted from the buffer amplifier. Therefore, any audio head unit can be freely changed for the one already mounted on the vehicle as long as the audio head unit contains therein a power amplifier.

Vehicle-mounted noise control apparatus

An acoustic signal reproduction device includes a reproduction speaker and a signal processing section for generating an acoustic signal for causing a listener to recognize a reference speaker. The signal processing section includes a compensation data input section for receiving compensation data from the outside of the acoustic signal reproduction device and a calculation section for calculating the acoustic signal based on the audio signal and the compensation data and outputting the acoustic signal to the reproduction speaker. The compensation data has a value H/C, where H is a transfer function from the reference speaker to a control point located in the vicinity of an ear of the listener, and C is a transfer function from the reproduction speaker to the control point located in the vicinity of the ear of the listener.

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Shijonawate, Japan

Kenichi Terai