Loudspeaker panel with a microphone and method for using both
View Patent ↗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.
1. A loudspeaker panel with a common open housing including several loudspeakers arranged in a plane such that the loudspeaker panel forms a dipole having a directional sound pressure characteristic, wherein an axis of symmetry of each loudspeaker is arranged in z-direction perpendicular to said plane and wherein to said housing a single microphone is attached outside said housing and on said plane.
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 a direct sound emitted from said loudspeakers.
3. The loudspeaker panel according to claim 1 , wherein said microphone is attached outside said housing with a distance of 1-2 cm.
4. A method for using a loudspeaker panel for audio presentation, said loudspeaker panel having a common open housing including several loudspeakers arranged in a plane such that the loudspeaker panel forms a dipole having a directional sound pressure characteristic, wherein an axis of symmetry of each loudspeaker is arranged in z-direction perpendicular to said plane and wherein to said housing a single microphone is attached outside said housing, said method comprising:
capturing background noise with said microphone;
capturing a loudspeaker signal with said microphone;
using a microphone output signal for controlling a sound pressure level output from said loudspeakers.
5. The method according to claim 4 , wherein a signal driving said loudspeakers is frequency compensated.
6. The method according to claim 4 , wherein an output signal of said microphone is spectrally filtered such that in a first frequency band a suppression of a 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.
7. The method according to claim 4 , wherein a loudness of the loudspeaker panel is adjusted to a constant level above a level of said background noise.
8. The method of claim 4 , further comprising presenting audio for supermarket advertisement or for audio information systems in exhibitions.
9. The method of claim 4 , further comprising documenting over time the sound pressure level output from said loudspeakers.
10. The method of claim 4 , further comprising presenting audio for determining defects in said loudspeaker panel.