Ambient Noise Sound Level Compensation

Abstract

An ambient noise compensation system determines an ambient noise level of a listening area. The ambient noise level may be calculated from the differences between a desired audio signal in the listening area, a measured background noise level in the listening area, and measured acoustic characteristics of the listening area. Based on the ambient noise level, the system adjusts a level of the desired audio signal so that it is audible over undesirable noise.

1 . A method of compensating for noise in a listening area, comprising: 
 measuring characteristics of substantially constant background noise in the listening area;    storing the characteristics of substantially constant background noise in the listening area;    projecting a test signal into the listening area;    measuring acoustic characteristics of the listening area;    storing the acoustic characteristics of the listening area;    projecting a desired audio signal into the listening area;    detecting an ambient sound in the listening area;    calculating an ambient noise level, where the calculating includes:    examining the ambient sound in the listening area with regard to the stored acoustic characteristics of the listening area and with regard to the stored characteristics of substantially constant background noise in the listening area; and    adjusting a level of the desired audio signal in response to the ambient noise level.    
     
     
         2 . The method of  claim 1 , 
 where the detecting includes measuring levels of the ambient sound among a set of frequency ranges; and    where the calculating further comprises, in each frequency range among the set of frequency ranges:    scaling a level of the ambient sound to account for the acoustic characteristics of the listening area, and    offsetting a level of the ambient sound to remove a contribution of the substantially constant background noise.    
     
     
         3 . The method of  claim 1 , where the detecting includes measuring levels of the ambient sound among a set of frequency ranges.  
     
     
         4 . The method of  claim 1 , where the detecting includes measuring logarithmic levels of the ambient sound among a set of frequency ranges.  
     
     
         5 . The method of  claim 1 , where the detecting includes measuring levels of the ambient sound among a set of frequency ranges, the set of frequency ranges including: 
 a first frequency range from about 100 Hz to about 145 Hz;    a second frequency range from about 145 Hz to about 211 Hz;    a third frequency range from about 211 Hz to about 307 Hz;    a fourth frequency range from about 307 Hz to about 447 Hz;    a fifth frequency range from about 447 Hz to about 650 Hz;    a sixth frequency range from about 650 Hz to about 944 Hz;    a seventh frequency range from about 944 Hz to about 1372 Hz; and    an eighth frequency range and from about 1372 Hz to about 2000 Hz.    
     
     
         6 . The method of  claim 1 , where the calculating further comprises: 
 adjusting the ambient noise level to account for the acoustic characteristics of the listening area.    
     
     
         7 . The method of  claim 1 , where the calculating further comprises: 
 adjusting the ambient noise level to remove a contribution of the substantially constant background noise.    
     
     
         8 . The method of  claim 1 , where the calculating further comprises: 
 scaling the ambient noise level to account for the acoustic characteristics of the listening area, and    offsetting the ambient noise level to remove a contribution of the substantially constant background noise.    
     
     
         9 . The method of  claim 1 , where the adjusting the level of the desired audio signal includes: 
 boosting the desired audio signal in response to a sensitivity setting.    
     
     
         10 . The method of  claim 1 , where the adjusting the level of the desired audio signal includes: 
 limiting the level of the desired audio signal in response to a max boost setting.    
     
     
         11 . A computer-readable medium storing a computer-executable program code for compensating for noise in a listening area, said computer-executable program code comprising: 
 code for measuring characteristics of substantially constant background noise in the listening area;    code for storing the characteristics of substantially constant background noise in the listening area;    code for projecting a test signal into the listening area;    code for measuring acoustic characteristics of the listening area;    code for storing the acoustic characteristics of the listening area;    code for projecting a desired audio signal into the listening area;    code for detecting an ambient sound in the listening area;    code for calculating an ambient noise level, where the code for calculating includes:    code for examining the ambient sound in the listening area with regard to the stored acoustic characteristics of the listening area and with regard to the stored characteristics of substantially constant background noise in the listening area; and    code for adjusting a level of the desired audio signal in response to the ambient noise level.    
     
     
         12 . The computer-readable medium of  claim 11 , 
 where the code for detecting includes code for measuring levels of the ambient sound among a set of frequency ranges; and    where the code for calculating further comprises, in each frequency range among the set of frequency ranges:    code for scaling a level of the ambient sound to account for the acoustic characteristics of the listening area, and    code for offsetting a level of the ambient sound to remove a contribution of the substantially constant background noise.    
     
     
         13 . The computer-readable medium of  claim 11 , where the computer-readable medium is one of: a magnetic-storage medium, a nonvolatile semiconductor memory, or an optical storage medium.  
     
     
         14 . The computer-readable medium of  claim 11 , where the computer-readable medium is a compact disk.  
     
     
         15 . A noise compensation system including: 
 a variable amplifier configured to receive an audio input signal and to generate an audio output signal in response to the audio input signal;    where the variable amplifier is further configured to receive an adjustment signal and to control an output level of the audio output signal in response to the adjustment signal;    a memory capable of storing listening-area characteristics, where the listening-area characteristics include information regarding a substantially constant-level background noise in the listening area and information regarding an acoustic response of the listening area;    a noise detection circuit coupled to the memory and to the variable amplifier, configured to receive the listening-area characteristics from the memory, and configured to receive the audio output signal from the variable amplifier;    where the noise detection circuit is further configured to receive an ambient sound input signal and to generate the adjustment signal in response to the ambient sound input signal, the audio output signal, and the listening-area characteristics.    
     
     
         16 . A method of compensating for noise in a listening area, comprising: 
 receiving an audio input signal;    receiving an ambient sound input signal;    recalling listening-area characteristics, where the listening-area characteristics include information regarding a substantially constant-level background noise in the listening area and information regarding an acoustic response of the listening area; and    scaling the audio input signal in response to the audio output signal, the ambient sound input signal, and the listening-area characteristics.    
     
     
         17 . A computer-readable medium storing a computer-executable program code for compensating for noise in a listening area, said computer-executable program code comprising: 
 code for receiving an audio input signal;    code for receiving an ambient sound input signal;    code for recalling listening-area characteristics, where the listening-area characteristics include information regarding a substantially constant-level background noise in the listening area and information regarding an acoustic response of the listening area; and    code for scaling the audio input signal in response to the audio output signal, the ambient sound input signal, and the listening-area characteristics.    
     
     
         18 . The computer-readable medium of  claim 17 , where the computer-readable medium is one of: a magnetic-storage medium, a nonvolatile semiconductor memory, or an optical storage medium.  
     
     
         19 . The computer-readable medium of  claim 17 , where the computer-readable medium is a compact disk.