Simplified communication system

A simplex digital voice enhancement communication system comprising in combination:

• a first acoustic zone;
• a second acoustic zone;
• a first microphone in said first zone;
• a first loudspeaker in said first zone;
• a second microphone in said second zone;
• a second loudspeaker in said second zone;
• a voice sensitive gated switch having a first mode supplying the output of said first microphone over a first channel to said second loudspeaker, and having a second mode supplying the output of said second microphone over a second channel to said first loudspeaker;
• a first noise sensitive bandpass filter in said first channel;
• a first equalization filter in said first channel;
• a second noise sensitive bandpass filter in said second channel;
• a second noise sensitive bandpass filter in said second channel;
• a second equalization filter in said second channel,
• wherein:
• said voice sensitive gated switch in said first mode substantially blocks transmission from said second microphone to said first loudspeaker;
• said voice sensitive gated switch in said second mode substantially blocks transmission from said first microphone to said second loudspeaker;
• said first and second modes of said voice sensitive gated switch are mutually exclusive such that only one of said channels can be active at a time;
• said first noise sensitive bandpass filter comprises 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 first person in said first zone transmitted from said first microphone to said second loudspeaker;
• said first equalization filter reduces resonance peaks in the acoustic transfer function between said second loudspeaker in said second zone and said first microphone in said first zone to reduce feedback by damping resonance peaks;
• said second noise sensitive bandpass filter comprises a second 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 second person in said second zone transmitted from said second microphone to said first loudspeaker;
• said second equalization filter reduces resonance peaks in the acoustic transfer function between said first loudspeaker in said first zone and said second microphone in said second zone to reduce feedback by damping resonance peaks;
• said system is in a vehicle, and each of said first and second highpass filters is vehicle speed sensitive,
• such that at higher vehicle speeds and resulting higher noise levels, lower frequency speech content of vehicle occupants is blocked and higher frequency speech content of vehicle occupants is passed, the lower frequency speech content of vehicle occupants being otherwise masked at higher speeds by broadband vehicle and wind noise, so that the reduced bandwidth and the absence of the lower frequency speech content of vehicle occupants does not sacrifice the perceived quality of speech,
• and such that at lower vehicle speeds and resulting lower noise levels, the cutoff frequency of each of said first and second highpass filters is lowered such that lower frequency speech content of vehicle occupants is passed, in addition to higher frequency speech content of vehicle occupants, to provide enriched low frequency performance, and overcome objections to a tinny sounding system in said vehicle;
• wherein:
• said first microphone is acoustically coupled to said second loudspeaker;
• said second microphone is acoustically coupled to said first loudspeaker;
• said voice sensitive gated switch comprises two voice activity detector gates, a first gate detecting the output of said first microphone, and a second gate detecting the output of said second microphone.

A simplex digital voice enhancement communication system comprising in combination:

• a first acoustic zone;
• a second acoustic zone;
• a first microphone in said first zone;
• a first loudspeaker in said first zone;
• a second microphone in said second zone;
• a second loudspeaker in said second zone;
• a voice sensitive gated switch having a first mode supplying the output of said first microphone over a first channel to said second loudspeaker, and having a second mode supplying the output of said second microphone over a second channel to said first loudspeaker;
• a first noise sensitive bandpass filter in said first channel;
• a first equalization filter in said first channel;
• a second noise sensitive bandpass filter in said second channel;
• a second noise sensitive bandpass filter in said second channel;
• a second equalization filter in said second channel,
• wherein:
• said voice sensitive gated switch in said first mode substantially blocks transmission from said second microphone to said first loudspeaker;
• said voice sensitive gated switch in said second mode substantially blocks transmission from said first microphone to said second loudspeaker;
• said first and second modes of said voice sensitive gated switch are mutually exclusive such that only one of said channels can be active at a time;
• said first noise sensitive bandpass filter comprises 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 first person in said first zone transmitted from said first microphone to said second loudspeaker;
• said first equalization filter reduces resonance peaks in the acoustic transfer function between said second loudspeaker in said second zone and said first microphone in said first zone to reduce feedback by damping resonance peaks;
• said second noise sensitive bandpass filter comprises a second 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 second person in said second zone transmitted from said second microphone to said first loudspeaker;
• said second equalization filter reduces resonance peaks in the acoustic transfer function between said first loudspeaker in said first zone and said second microphone in said second zone to reduce feedback by damping resonance peaks;
• said system is in a vehicle, and each of said first and second highpass filters is vehicle speed sensitive,
• such that at higher vehicle speeds and resulting higher noise levels, lower frequency speech content is blocked and higher frequency speech content is passed, the lower frequency speech content being otherwise masked at higher speeds by broadband vehicle and wind noise, so that the reduced bandwidth and the absence of the lower frequency speech content does not sacrifice the perceived quality of speech,
• and such that at lower vehicle speeds and resulting lower noise levels, the cutoff frequency of each of said first and second highpass filters is lowered such that lower frequency speech content is passed, in addition to higher frequency speech content, to provide enriched low frequency performance, and overcome objections to a tinny sounding system in said vehicle;
• said vehicle has an in-cabin audio system, and comprising a digital voice enhancement activation switch actuating said voice sensitive gated switch and providing an audio mute signal muting said in-cabin audio system;
• wherein:
• said first microphone is acoustically coupled to said second loudspeaker;
• said second microphone is acoustically coupled to said first loudspeaker;
• said voice sensitive gated switch comprises two voice activity detector gates, a first gate detecting the output of said first microphone and a second gate detecting the output of said second microphone.