Microphone actuation control system suitable for teleconference systems

A microphone system comprising:

• a plurality of microphones, each said microphone responsive to speech for generating an electrical microphone signal carrying speech information;
• gating means receiving each said microphone signal and gating a said microphone signal to gate ON its associated microphone in response to a gating signal;
• threshold means for generating a threshold signal level representative of room noise;
• comparator means for comparing the amplitude of each said microphone signal with said threshold,
• said gating means for generating a gating signal when a said microphone signal reaches a predetermined relationship with said threshold signal level;
• loudspeaker means for generating sound in the area of said microphones, said loudspeaker means being driven by a loudspeaker signal;
• inhibit signal generator means for generating an electrical inhibit signal related to said loudspeaker signal for inhibiting said gating means from gating a said microphone in response to sound from said loudspeaker means, said inhibit signal modifying said threshold signal level for inhibiting microphone gating for direct loudspeaker sounds and said threshold signal level tracking said microphone level for inhibiting microphone gating for reverberant loudspeaker sounds.

A microphone system comprising:

• a microphone, said microphone responsive to speech for generating an electrical microphone signal carrying speech information;
• gating means receiving said microphone signal and gating said microphone signal to gate ON its associated microphone in response to a gating signal;
• threshold means for generating a threshold signal level representative of room noise;
• comparator means for comparing the amplitude of said microphone signal with said threshold,
• said gating means for generating a gating signal when said microphone signal reaches a predetermined relationship with said threshold signal level;
• loudspeaker means for generating sound in the area of said microphone, said loudspeaker means being driven by a loudspeaker signal;
• inhibit signal generator means for generating an electrical inhibit signal related to said loudspeaker signal for inhibiting said gating means from gating said microphone in response to sound from said loudspeaker means, said inhibit signal modifying said threshold signal level for inhibiting microphone gating for direct loudspeaker sounds and said threshold signal level tracking said microphone level for inhibiting microphone gating for reverberant loudspeaker sounds.

A microphone system, including:

• a noise adapting threshold circuitry, said circuitry including:
• (i) means for generating an amplitude signal representative of the amplitude of a microphone input signal;
• (ii) capacitive means for storing charge for generating a threshold voltage level;
• (iii) amplifier means responsive to said amplitude signal for charging said capacitive means;
• (iv) feedback means for feeding back said threshold voltage to said amplifier for controlling charging of said capacitive means;
• and
• (v) means for developing a signal representative of loudspeaker sound, said developing means applying said signal to said capacitive means and to said input of said amplifier means.

A noise adapting threshold circuit, comprising:

• (i) means for generating an amplitude signal representative of the amplitude of a microphone input signal;
• (ii) capacitive means for storing charge for generating a threshold voltage level;
• (iii) amplifier means responsive to said amplitude signal for charging said capacitive means;
• (iv) discharge means for discharging said capacitive means at a rate substantially equal to the rate of decrease of said amplitude signal;
• (v) scaling means for generating a scaled representation of said amplitude signal;
• and
• (vi) comparison means for comparing said threshold voltage level with said scaled representation of said amplitude signal.

A microphone system comprising:

• a plurality of microphones, each said microphone responsive to speech for generating an electrical microphone signal carrying speech information;
• gating means receiving each said microphone signal and gating a said microphone sigal to gate ON its associated microphone in response to a gating signal, said gating means including:
• monitoring circuitry for providing and continuously monitoring signals reppresentative of the microphone signal amplitudes of said microphone signals for generating an electrical MAX signal having an amplitude which serves as a threshold representative of a maximum microphone signal amplitude, said monitoring circuitry comparing signals representative of the amplitude level of each said microphone signal with said MAX signal for responsively generating a trigger signal associated with a said microphone to gate ON the associated microphone;
• gating signal generation means responsive to a said trigger signal for generating a gating signal of at least a predetermined minimal non-zero time duration for gating ON the microphone associated with said trigger signal;
• and
• gate means responsive to a said gating signal for gating ON an associated microphone.