SELF-CALIBRATING LOUDSPEAKER SYSTEM

• US 20100272270A1
• Filed: 09/02/2006
• Published: 10/28/2010
• Est. Priority Date: 09/02/2005
• Status: Active Grant

• Current Assignee: Harman International Industries Incorporated (Samsung Group)
• Original Assignee: Harman International Industries Incorporated (Samsung Group)
• Inventors: Lee, John, Wright, Gregory, Chaikin, Peter, Paganini, Miguel, Christopherson, Geoffrey, Ellison, Brian, Shuttleworth, Timothy, Reed, C. Rex
• Granted Patent: US 8,577,048 B2
• Time in Patent Office: Days
• US Class Current: 381/59
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04R 29/008 Visual indication of individual signal levels visual indication of stereophonic sound image H04S7/40
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

Systems and methods for calibrating a loudspeaker with a connection to a microphone located at a listening area in a room. The loudspeaker includes self-calibration functions to adjust speaker characteristics according to effects generated by operating the loudspeaker in the room. In one example, the microphone picks up a test signal generated by the loudspeaker and the loudspeaker uses the test signal to determine the loudspeaker frequency response. The frequency response is analyzed below a selected low frequency value for a room mode. The loudspeaker generates parameters for a digital filter to compensate for the room modes. In another example, the loudspeaker may be networked with other speakers to perform calibration functions on all of the loudspeakers in the network.

Claims

1. A loudspeaker comprising:

at least one speaker;

at least one audio input to receive an audio signal;

at least one microphone input to connect to at least one microphone;

a loudspeaker control system having an audio signal processor to process the at least one audio signal, the audio signal processor being configurable to adjust sound characteristics of the speaker; and

the loudspeaker control system including a self-calibration function to perform with the at least one microphone in a selected listening area in a room, the self-calibration function operable to generate a test sound via the at least one speaker for pickup by the at least one microphone and to analyze a test signal received by the at least one microphone to determine at least one sound effect caused by the room at the listening area, and to configure the audio signal processor to compensate for the sound effects caused by the room by adjusting the sound characteristics of the speaker.

5. The loudspeaker of claim 1 where the self-calibration function includes a room mode correction function that analyzes the test signal by determining a frequency response, analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes, and generating parameters for a digital filter to compensate for the room modes.

6. The loudspeaker of claim 1 further comprising:

a network interface to connect to at least one other loudspeaker in a loudspeaker network; and

a network calibration controller to identify each loudspeaker in the loudspeaker network and to perform at least one calibration function for each loudspeaker.

7. The loudspeaker of claim 6 where the at least one calibration function includes a room mode correction function that analyzes the test signal by determining a frequency response, analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes, and generating parameters for a digital filter to compensate for the room modes;

and where the network calibration controller performs the room mode correction function for each speaker.

8. The loudspeaker of claim 6 where the at least one calibration function includes a speaker positioning function to calculate a distance from the at least one microphone for each loudspeaker, to calculate a digital signal delay for each loudspeaker to use to sound as though the loudspeakers in the loudspeaker network were equidistant to the microphone.

9. The loudspeaker of claim 6 where the at least one calibration function includes a sound pressure equalization function to determine a relative sound pressure level at the microphone for each loudspeaker, and to calculate a signal attenuation to use to have all loudspeakers contribute equal sound pressure level at the microphone.

10. A system for calibrating a loudspeaker comprising:

at least one microphone input to connect to at least one microphone;

a loudspeaker control system mounted in the loudspeaker, the loudspeaker control system having an audio signal processor configurable to adjust sound characteristics of the loudspeaker, and a self-calibration function to perform with the microphone in a selected listening area in a room, the self-calibration function operable to generate a test sound via the loudspeaker for pickup by the microphone and to analyze a test signal received by the microphone in response to the test sound to determine at least one sound effect caused by the room at the listening area, and to configure the audio signal processor to compensate for the sound effects caused by the room by adjusting the sound characteristics of the loudspeaker.

11. The system of claim 10 further comprising:

a calibration initiation input to initiate execution of the self-calibration function.

12. The system of claim 11 where the calibration initiation input includes a push-button mounted on the loudspeaker.

13. The system of claim 11 where the calibration initiation input includes a wireless remote receiver to receive a signal to initiate execution of the self-calibration function.

14. The system of claim 10 where the self-calibration function includes a room mode correction function that analyzes the test signal by determining a frequency response, analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes, and generating parameters for a digital filter to compensate for the room modes.

15. The system of claim 10 further comprising:

a network interface to connect to at least one other loudspeaker in a loudspeaker network; and

a network calibration controller to identify each loudspeaker in the loudspeaker network and to perform at least one calibration function for each loudspeaker.

16. The system of claim 15 where the at least one calibration function includes a room mode correction function that analyzes the test signal by determining a frequency response, analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes, and generating parameters for a digital filter to compensate for the room modes;

and where the network calibration controller performs the room mode correction function for each loudspeaker.

2. The loudspeaker of claim 1 further comprising:

a calibration initiation input to initiate execution of the self-calibration function.

3. The loudspeaker of claim 2 where the calibration initiation input includes a push-button mounted on the loudspeaker.

4. The loudspeaker of claim 2 where the calibration initiation input includes a wireless remote receiver to receive a signal to initiate execution of the self-calibration function.

17. The system of claim 15 where the at least one calibration function includes a speaker positioning function to calculate a distance from the microphone for each loudspeaker, to calculate a digital signal delay for each loudspeaker to use to sound as though the loudspeakers in the loudspeaker network were equidistant to the microphone.

18. The loudspeaker of claim 15 where the at least one calibration function includes a sound pressure equalization function to determine a relative sound pressure level at the microphone for each loudspeaker, and to calculate a signal attenuation to use to have all loudspeakers contribute equal sound pressure level at the microphone.

19. The method of claim 16 further comprising:

connecting the loudspeaker to at least one other loudspeaker in a loudspeaker network;

identifying each loudspeaker in the loudspeaker network; and

performing at least one calibration function for each loudspeaker.

20. The method of claim 19 where the at least one calibration function includes a method comprising:

for each loudspeaker, emitting a test sound for pickup by the microphone;

determining a frequency response of each loudspeaker from the test signal picked up by the microphone for each loudspeaker;

analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes generated by the test sound from each loudspeaker in the room; and

generating parameters for a digital filter in each loudspeaker to compensate for the room modes.

21. The method of claim 19 further comprising a method comprising:

calculating a distance from the microphone to each loudspeaker;

calculating a digital signal delay for each loudspeaker to use to sound as though the loudspeakers in the loudspeaker network were equidistant to the microphone; and

inserting the digital signal delay for each loudspeaker into audio signals to each corresponding loudspeaker.

22. The method of claim 19 further comprising a method comprising:

determining a relative sound pressure level at the microphone for each loudspeaker; and

calculating a signal attenuation to use in each loudspeaker to have all loudspeakers contribute equal sound pressure level at the microphone.

16-1. A method for calibrating a loudspeaker comprising:

connecting a microphone to the loudspeaker;

placing the microphone in a listening area in a room;

generating a test sound and receiving a test signal at the microphone in response to the test sound;

determining at least one sound effect caused by the room at the listening area; and

configuring the loudspeaker to compensate for the sound effects caused by the room by adjusting the sound characteristics of the speaker

17-2. The method of claim 16 further comprising initiating a self-calibration function before the step of generating the test sound.

18-3. The method of claim 17 where the step of initiating the self-calibration function includes the step of pressing a push-button mounted on the speaker.

18-4. The method of claim 16 where the self-calibration function includes a method comprising:

analyzing the test signal by determining a frequency response;

analyzing the frequency response at a low frequency range below a selected frequency to identify any room modes; and

generating parameters for a digital filter to compensate for the room modes.

23. A meter display on a panel of a loudspeaker, the meter display comprising:

a plurality of level values extending across the meter display;

a level indicator to visually signal a parameter level by moving to one of the plurality of levels on the meter display;

a meter display controller to convert a parameter value to a level signal indicative of the parameter level; and

a meter display driver connected to the meter display to receive the level signal and drive the level indicator in accordance with the level signal.

24. The meter display of claim 23 where the plurality of levels includes a plurality of lights extending lengthwise on the meter display, the lights having substantially the same length;

the plurality of lights including;

a first light on one end of the meter display to indicate a lower limit of the parameter level;

a last light on the opposite end of the meter display to indicate an upper limit of the parameter level;

a set of lights between the first and last lights to indicate increasing levels from the lower limit to the upper limit;

where the parameter level is indicated by lighting a number of lights corresponding with the level signal starting with the first light.

25. The meter display of claim 24 where the plurality of lights emit light of different colors, each color representing a selected level.

26. The meter display of claim 23 where the parameter value received by the meter display controller represents a speaker characteristic including volume, power output, speaker sound pressure level, equalization setting, input selection, currently selected preset.

27. The meter display of claim 26 where the plurality of levels indicate output in SPL (“

sound pressure level”

) measured at or calculated for the mix position, or dB/dBFS.

28. The meter display of claim 23 where the parameter value received by the meter display controller represents power output and the upper limit represents a maximum rated power output of the speaker.