Abstract: Sound picked up by a microphone of a first sound field is reproduced by a speaker of a second sound field, and a sound picked up by a microphone of the second sound field is reproduced by the speaker of the first sound field. Sound pressure detection section detects a sound pressure of a sound present in the second (or first) sound field picked up by the microphone of the second (or first) sound field, other than a sound reproduced by the speaker of the first (or second) sound field. Other sound pressure detection section detects a sound pressure with which the sound picked up by the microphone of the second (or first) sound field and reproduced by the speaker of the first (or second) sound field is picked up by the microphone of the first (or second) sound field. Sound-pressure-difference detection section adjusts a gain of an automatic gain adjustment section in such a manner that the two detected sound pressures assume a predetermined relationship.

Abstract: In the floor base panel (40), an area on the support board (33) of the vibration proof support leg (30) is formed solid, and in the other area, a plurality of cavities (41) extending parallel to the floor surface are formed. Thereby, because the vibration energy propagated from the impact point of the floor base panel (40) is reflected on the boundary between the cavity formation area and the solid area, and repeatedly passes the cavity formation area, it is attenuated in a short time, and the vibration energy or sound energy transmitted to a slab (20) can be reduced.

Abstract: Noises in an interior of an automobile are estimated based on sensed values of sensors that sense a speed (driving speed), an accelerator opening angle, and an engine speed respectively. This estimation is carried out by searching a noise estimation database. A masking characteristic of an audio signal is deduced based on the estimated noises. An equalizing characteristic to prevent a masking of the audio signal is decided based on the masking characteristic, and then the audio signal is equalized.

Abstract: Two signals, which are mutually correlated, are subjected to a principal component analysis and converted into two signals being put in an orthogonal relation, thereby generating two signals being non-correlated. Those two signals are reproduced by speakers, and the voice generated from the speakers are collected by microphones. The cross spectra of a signal as the result of subtracting an echo canceling signal from a voice collected by each microphone, and a voice before it is generated from the speaker, are obtained. Those cross spectra are ensemble-averaged for a predetermined period of time, and inverse Fourier transformed, thereby producing impulse response estimation errors of each filter. Impulse responses of those filters are updated so as to cancel those impulse response estimation errors.

Abstract: Microphones are provided to an intake port of an engine and a wall surface of an engine room on the interior side respectively to collect an engine sound. The engine sound is processed by a signal processing portion and output via a speaker provided to an interior of a vehicle. Filters for simulating the noise insulating characteristic in the interior of the vehicle and filters for processing the engine sound to emphasize the driving conditions are provided to the signal processing portion. Filter characteristics of the filters are decided in response to sensed values of an engine revolution sensor 30, an accelerator opening angle sensor, and a speed sensor. The driving conditions are emphasized by filtering the engine sound based on the filter characteristics.

Abstract: Stereo sound signals are reproduced directly from loudspeakers (SP(L), SP(R)). By using a sum signal and a difference signal of the stereo sound signals as a reference signal, and according to a cross spectrum calculation of the reference signal with a microphone-collected sound signal, calculation is performed to obtain transfer functions of four sound transfer systems between the loudspeakers (SP(L), SP(R)) and microphones (MC(L), MC(R)). The transfer functions obtained are subjected to inverse Fourier transform to obtain impulse responses, which are set in filter means (40-1 to 40-4) to create echo cancel signals and perform echo canceling. This solves the problem of an indefinite coefficient in the echo cancel technique of a multi-channel sound signal.

Abstract: In the floor base panel (40), an area on the support board (33) of the vibration proof support leg (30) is formed solid, and in the other area, a plurality of cavities (41) extending in the parallel direction to the floor surface are formed. Thereby, because the vibration energy propagated from the impact point of the floor base panel (40) is reflected on the boundary between the cavity formation area and the sold area, and repeatedly passes the cavity formation area, it is attenuated in a short time, and the vibration energy or sound energy transmitted to a slab (20) can be reduced.

Abstract: Two signals, which are mutually correlated, are subjected to a principal component analysis and converted into two signals being put in an orthogonal relation, thereby generating two signals being non-correlated. Those two signals are reproduced by speakers, and the voice generated from the speakers are collected by microphones. The cross spectra of a signal as the result of subtracting an echo canceling signal from a voice collected by each microphone, and a voice before it is generated from the speaker, are obtained. Those cross spectra are ensemble-averaged for a predetermined period of time, and inverse Fourier transformed, thereby producing impulse response estimation errors of each filter. Impulse responses of those filters are updated so as to cancel those impulse response estimation errors.

Abstract: Sound picked up by a microphone of a first sound field is reproduced by a speaker of a second sound field, and a sound picked up by a microphone of the second sound field is reproduced by the speaker of the first sound field. Sound pressure detection section detects a sound pressure of a sound present in the second (or first) sound field picked up by the microphone of the second (or first) sound field, other than a sound reproduced by the speaker of the first (or second) sound field. Other sound pressure detection section detects a sound pressure with which the sound picked up by the microphone of the second (or first) sound field and reproduced by the speaker of the first (or second) sound field is picked up by the microphone of the first (or second) sound field. Sound-pressure-difference detection section adjusts a gain of an automatic gain adjustment section in such a manner that the two detected sound pressures assume a predetermined relationship.