Toa Corporation

Etani Electronics Co., Ltd.

Daisuke Higashihara

Koichi Tsuchiya

Shokichiro Hino

Tomohiko Endo

Akinori Nakano

Microphone with built-in speaker

A resonant frequency characteristic in a resonant space is detected, based on a base amplitude frequency characteristic obtained by outputting a sound wave of a specified measurement signal from a speakerdisposed in a sound spaceand by receiving the sound wave in a microphonedisposed in the sound space, a first amplitude frequency characteristic obtained by outputting, from the speaker, a sound wave of the measurement signal and a signal output from the microphoneand by receiving the sound wave in the microphone, and a second amplitude frequency characteristic obtained by outputting, from the speaker, a sound wave of the measurement signal and a phase inverted signal obtain by inverting a phase of the signal output from the microphoneand by receiving the sound wave in the microphone

Resonance frequency determining method, resonance frequency selecting method, and resonance frequency determining apparatus

Resonant frequencies fand fdetected in a resonant space are determined as center frequencies of a dip. Based on measurement values at a speaker and a microphone in the resonant space, a basic amplitude frequency characteristic Ca and a target amplitude frequency characteristic Cd are found. A smoothness degree on a frequency axis is larger in the target amplitude frequency characteristic Cd than the basic amplitude frequency characteristic Ca. A damping level and quality factor of the dip are determined based on a difference between the basic amplitude frequency characteristic Ca and the target amplitude frequency characteristic Cd in the center frequencies fand fof the dip and frequencies near the center frequencies.

Dip filter frequency characteristic decision method

A howling margin measuring devicecomprises processing meanscomposed of gain controlling meansand a compressorwhich are connected in series and controlling means. The gain controlling meansoutputs an input sound signal after giving a gain thereto. If the level of a sound signal input to the compressoris equal to or higher than a threshold level, the compressoroutputs the sound signal after compressing it with a specified ratio. The controlling meansis capable of controlling the gain of the gain controlling meansand reading the compression level of the compressor. The controlling meansreads the compression level of the compressorwhile gradually increasing the gain of the gain controlling means, determines whether or not howling has been generated based on whether the read compression level has a value equal to or higher than a specified value, and calculates a howling margin based on the gain of the gain controlling meanswhen it is determined that howling has been generated.

Howling margin measuring device

A devicefor measuring a propagation time of a sound wave comprises a sound source meansand a calculation means. The sound source meansoutputs a time stretched pulse as a sound source signal input to a speaker. The calculation meanscalculates a cross-correlation function of the time stretched pulse and the sound signal which is output from the speakerand is received in a microphone. Based on the cross-correlation function, the propagation time of the sound wave between the speakerand the microphoneis found.

Method and device for measuring sound wave propagation time between loudspeaker and microphone

A device for detecting a resonant frequency comprises a sound source, a switch, a mixer, and a sound meter. The switch and mixer are capable of switching between a first state in which the switch and mixer output a measurement signal and a second state in which the switch and mixer output a synthesized signal containing the measurement signal and the signal output from a microphone. The device detects the resonant frequency based on comparison between the first amplitude frequency characteristic measured in the first state and the second amplitude frequency characteristic measured in the second state.

Growing community of inventors

Hyogo, Japan

Daisuke Higashihara