Audio system

• US 6,477,255 B1
• Filed: 08/05/1999
• Issued: 11/05/2002
• Est. Priority Date: 08/05/1998
• Status: Expired due to Fees

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Matsushita, Fumio, Yoshida, Minoru, Ohta, Yoshiki, Kumada, Satoshi
• Primary Examiner(s): Mei, Xu
• Application Number:
  US09/368,348
• Time in Patent Office: 1,188 Days
• Field of Search: 281/302, 281/300, 281/307, 281/61, 281/63, 281/86, 281/365, 281/17, 281/18, 281/19
• US Class Current: 381/86
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 5/02 Spatial or constructional arrangements of loudspeakers
• CPC Class Codes: H04S 1/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30

Abstract

A rear speaker and a front speaker are provided in a room. A microphone is disposed at a listening position between the front and rear speakers for picking up a first sound from the front speakers and a second sound from the rear speaker. Time lags of the first sound and the second sound is obtained from the outputs of the microphone, and the time difference between the time lags is obtained. An antiphase audio signal opposite to a reflected composite signal included in the first sound picked up by the microphone is provided by the sound field correcting circuit. The antiphase audio signal with the same amplitude is delayed based on the time difference and emitted from the rear speaker so as to cancel the reflected composite signal.

Claims

1. An audio system for a room comprising:

a sound source;

a first speaker for emitting a first sound including a reflected composite signal based on an audio signal from the sound source;

a second speaker for emitting a second sound;

a microphone disposed at a listening position between the first and second speakers for picking up the first sound from the first speaker and the second sound from the second speaker;

control means for obtaining a time difference and a sound pressure difference between the reflected composite signal and the second sound picked up by the microphone based on characteristic information of the first and second sounds;

phase adjusting means for inverting the phase of the audio signal from the sound source for producing an antiphase audio signal;

filter means for extracting an input audio signal of a predetermined frequency band from the antiphase audio signal, in which the predetermined frequency band corresponds to a frequency band of the reflected composite signal included in the first sound picked up by the microphone;

delay means for delaying the antiphase audio signal based on the time difference so that the second sound coincides with the first sound at the microphone;

amplitude adjusting means for adjusting the amplitude of the antiphase audio signal so as to reduce the second pressure difference;

applying means for applying the inverted antiphase audio signal to the second speaker for emitting the second sound.

3. The system according to claim 1 wherein the frequency band of the filter means is obtained from the following formula,

4. The system according to claim 1 wherein the time difference of the delay means is obtained based on the time difference between a first propagation delay time and a second propagation delay time.

5. The system according to claim 1 wherein the time difference corresponds to a propagation time difference between a propagation time of the first sound to the listening position and a propagation time of the second sound to the listening position.

6. The system according to claim 1 wherein at least one of the filter means, phase adjusting means, delay means and amplitude adjusting means is provided to be externally adjusted.

7. The system according to claim 1 wherein the filter means is a band pass filter.

8. The system according to claim 1 wherein the filter means is a low pass filter.

9. The system according to claim 1 wherein the audio system is an audio system mounted on a motor vehicle.

2. An audio system for a room comprising:

a sound source;

a first speaker for emitting a first sound based on an audio signal from the sound source;

a second speaker for emitting a second sound;

phase adjusting means for inverting the phase of the audio signal from the sound source for producing an antiphase audio signal;

filter means for extracting an input audio signal of a predetermined frequency band from the antiphase audio signal, in which the predetermined frequency band corresponds to a frequency band of a reflected composite signal included in the first sound applied to a listening position;

delay means for delaying the antiphase audio signal a delay time obtained based on a time difference between a first time lag between the audio signal from the sound source and the first sound applied to the listening position, and second time lag between the audio signal from the sound source and the second sound applied to the listening position;

amplitude adjusting means for adjusting the amplitude of the antiphase audio signal so as to approximate to the second pressure of the first sound;

applying means for applying the inverted antiphase audio signal to the second speaker for emitting the second sound.