Loudspeaker panel with a microphone and method for using both

• US 20090245545A1
• Filed: 03/25/2009
• Published: 10/01/2009
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: InterDigital CE Patent Holdings SAS (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Schmidt, Juergen
• Granted Patent: US 8,280,063 B2
• Time in Patent Office: Days
• US Class Current: 381/182
• CPC Class Codes: H04R 1/403 loud-speakers
• CPC Class Codes: H04R 2201/403 Linear arrays of transducers

Abstract

In public audio presentation it is desirable that the playback loudness is continuously adapted to the background noise loudness. Such adaptation of the playback volume requires a continuous measurement of the loudness somewhere within the sound exposure area. A dipole loudspeaker panel has a strong attenuation of the emitted sound in the panel plane. When placing a microphone capsule in that plane but outside the panel, the sound emitted from the panel will be recorded by the microphone with a significant sound pressure level attenuation. Such specific microphone arrangement can capture the background noise without being unduly disturbed by the direct sound emitted from the loudspeakers.

Claims

1. A loudspeaker panel with a common housing including several loudspeakers arranged in a plane such that the loudspeaker panel forms a dipole having a directional sound pressure characteristic, wherein the axis of symmetry of each loudspeaker is arranged in z-direction perpendicular to said plane and wherein to said housing a microphone is attached outside said housing, for example with a distance of 1-2 cm, and basically on said plane but optionally shifted in said z-direction.

2. The loudspeaker panel according to claim 1, wherein said microphone is attached shifted in said z-direction such that said microphone receives a minimum sound pressure level from the direct sound emitted from said loudspeakers.

3. A method for using said loudspeaker panel according to claim 1 for audio presentation, said method including the steps:

capturing background noise with said microphone;

capturing the loudspeaker signal with said microphone;

using the microphone output signal for controlling the sound pressure level output from said loudspeakers.

4. The method according to claim 3, wherein the signal driving said loudspeakers is frequency compensated.

5. The method according to claim 3, wherein the microphone output signal is spectrally filtered such that in a first frequency band the suppression of the loudspeaker panel output signal is at its maximum, and that in a second frequency band the background noise and the loudspeaker panel output signal are measured together for determining the loudspeaker panel'"'"'s loudness.

6. The method according to claim 3, wherein the loudness of the loudspeaker panel is adjusted to a constant level above the level of said background noise.

7. Use of the method of claim 3 for supermarket advertisement or for audio information systems in exhibitions.

8. Use of the method of claim 3 for the documentation over time of the sound pressure level output from said loudspeakers.

9. Use of the method of claim 3 for determining defects in said loudspeaker panel.