Dual-microphone frequency amplitude response self-calibration

A self-calibrating multiple microphone system, comprising at least two microphones, comprising:

• the at least two microphones each receiving at least ambient noise signals;
• a noise minima tracker receiving the ambient noise signals from each of the at least two microphones and tracking noise minima in a time domain for each of the ambient noise signals from the at least two microphones by tracking the noise minima of each of the ambient noise signals from the at least two microphones for a predetermined number of frequency bins;
• a calibrator calculating an amplitude calibration value based on a ratio of the noise minima of each of the ambient noise signals from two of the at least two microphones by calculating the amplitude calibration value for each of the predetermined number of frequency bins based on the ratio of the noise minima of each of the ambient noise signals from the two of the at least two microphones;
• and
• an input filter coupled to at least one of the at least two microphones having a gain profile altered by the calculated amplitude calibration value to calibrate one of the at least two microphones relative to another of the at least two microphones.

A self-calibrating cellular telephone including at least two microphones, comprising:

• the at least two microphones on the self-calibrating cellular telephone each receiving at least ambient noise signals;
• a noise minima tracker receiving the ambient noise signals from each of the at least two microphones and tracking noise minima in a time domain for each of the ambient noise signals from the at least two microphones by tracking the noise minima of each of the ambient noise signals from the at least two microphones for a predetermined number of frequency bins;
• a calibrator calculating an amplitude calibration value based on a ratio of the noise minima of each of the ambient noise signals from two of the at least two microphones by calculating the amplitude calibration value for each of the predetermined number of frequency bins based on the ratio of the noise minima of each of the ambient noise signals from the two of the at least two microphones;
• and
• an input filter coupled to at least one of the at least two microphones having a gain profile altered by the calculated amplitude calibration value to calibrate one of the at least two microphones relative to another of the at least two microphones.

A self-calibrating cellular telephone including at least two microphones, comprising:

• the at least two microphones on the self-calibrating cellular telephone each receiving audio signals including ambient noise signals;
• a noise minima tracker receiving the ambient noise signals from the at least two microphones and tracking noise minima for each of the ambient noise signals from the at least two microphones;
• a calibrator calculating an amplitude calibration value based on a ratio of the noise minima of each of the ambient noise signals from two of the at least two microphones;
• and
• an input filter coupled to at least one of the at least two microphones having a gain profile altered by the calculated amplitude calibration value to calibrate one of the at least two microphones relative to another of the at least two microphones,
• wherein the noise minima tracker tracks the noise minima of each of the ambient noise signals from the at least two microphones for a predetermined number of frequency bins,
• wherein the calibrator calculates the amplitude calibration value for each frequency bin based on the ratio of the noise minima of each of the ambient noise signals from the two of the at least two microphones,
• wherein calculating the amplitude calibration value for each frequency bin further includes smoothing amplitude calibration value changes over time by multiplying the amplitude calibration value by a predetermined smoothing factor, and
• wherein the calibrator calculates the amplitude calibration value for each frequency bin based on the ratio of the noise minima of each of the ambient noise signals from the two of the at least two microphones as g[k] as follows:
• g[k]=alpha*g[k]+(1-alpha)*xMinEnv[k]/yMinEnv[k]
• where xMinEnv[k] represents a minima level for a particular frequency bin k for a signal x from one of the at least two microphones and yMinEnv[k] represents a minima level for a particular frequency bin k for the signal y from another of the at least two microphones and alpha represents the predetermined smoothing factor.

A self-calibrating cellular telephone including at least two microphones, comprising:

• the at least two microphones on the self-calibrating cellular telephone each receiving audio signals including ambient noise signals;
• a noise minima tracker receiving the ambient noise signals from the at least two microphones and tracking noise minima for each of the ambient noise signals from the at least two microphones;
• a calibrator calculating an amplitude calibration value based on a ratio of the noise minima of each of the ambient noise signals from two of the at least two microphones;
• and
• an input filter coupled to at least one of the at least two microphones having a gain profile altered by the calculated amplitude calibration value to calibrate one of the at least two microphones relative to another of the at least two microphones,
• wherein the noise minima tracker tracks the noise minima of each of the ambient noise signals from the at least two microphones for a predetermined number of frequency bins,
• wherein the calibrator calculates the amplitude calibration value for each frequency bin based on the ratio of the noise minima of each of the ambient noise signals from the two of the at least two microphones as g[k] as follows:
• g[k]=alpha*g[k]+(1-alpha)*xMinEnv[k]/yMinEnv[k]
• where xMinEnv[k] represents a minima level for a particular frequency bin k for a signal x from one of the at least two microphones and yMinEnv[k] represents a minima level for a particular frequency bin k for the signal y from another of the at least two microphones and alpha represents a predetermined smoothing factor.