Abstract: A digital voice enhancement, DVE, communication system includes an instability detector detecting an unstable acoustic feedback condition from a loudspeaker to a microphone by sensing a condition of the electrical signal transmitted from the microphone to the loudspeaker, and a corrective processor responsive to the instability detector to modify the electrical signal to reduce unstable acoustic feedback. The sensed condition may be magnitude, power, or, preferably, the sinusoidal characteristic of the electrical signal, namely the electrical signal becoming sinusoidal in nature.

Abstract: A digital voice enhancement, DVE, communication system includes a dynamic range processor and method altering dynamic range of the electrical signal from the microphone to the loudspeaker by applying nonlinear and/or differential gain thereto, preferably applied by a slope intercept formula.

Abstract: In a DVE, digital voice enhancement, communication system, the selection decision for choosing which microphone to be active is based on a given function of the speech of a respective talker relative to his/her acoustic environment at the respective microphone. The selection decision is based on a selection technique normalizing at least one of a) different microphone sensitivities and b) different background noise levels at the respective microphones, preferably based on the ratio of how much louder a talker speaks over the background noise at his/her respective microphone.

Abstract: An integrated vehicle voice enhancement system and hands-free cellular telephone system implements microphone steering techniques and noise reduction filtering to improve the intelligibility and clarity of transmitted signals. A microphone steering switch is provided for the cellular telephone interface which allows only one of the microphones to be switched in to an “on” state at any given time. The microphone steering switch generates a raw telephone input switch that is a combination of 100% of the designated primary microphone signal and approximately 20% of the microphone signals from microphones in the “off” state. In this manner, the telephone line does not appear dead to a listener on the other end of the telephone line when speech is not present in the telephone input signal. A noise reduction filter filters the raw telephone signal in the time domain in real time to improve the clarity of the telephone input signal when speech is present in the telephone input signal.

Abstract: A digital voice enhancement communication system, including a simplex system, has first and second acoustic zones, and respective microphones and loudspeakers. A voice sensitive gated switch has a first mode supplying the output of a first microphone in the first zone over a first channel to a second loudspeaker in the second zone, and has a second mode supplying the output of a second microphone in the second zone over a second channel to the first loudspeaker in the first zone. First and second noise sensitive bandpass filters and first and second equalization filters are provided in the first and second channels, respectively. Each noise sensitive bandpass filter is a noise responsive highpass filter having a filter cutoff effective at elevated noise levels and reducing bandwidth and making more gain available, to improve intelligibility of speech of a person in the respective zone transmitted from the respective microphone to the loudspeaker in the other zone.