Audio feedback suppressor
First Claim
1. Apparatus for minimizing feedback to an acoustic to electric signal transducer of an acoustic signal derived from an electric to acoustic transducer comprising means responsive to an electric input signal derived from the acoustic to electric transducer for randomly shifting the phase of the electric input signal by an amount independent of any characteristic of the input signal to derive an electric audio signal having a phase randomly shifted relative to the phase of the input signal, and means responsive to the phase shifted electric audio signal for supplying the phase shifted electric audio signal to the electric to acoustic transducer.
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Accused Products
Abstract
Positive feedback of an acoustic signal from a loud speaker to a microphone of a loud speaker system, i.e., howling, is prevented by randomly phase shifting an electric signal containing audio information supplied to the speaker. The random phase shifting is provided by variably delaying the electric signal in a serial analog register having a shift rate determined by an output signal of a pseudo random code generator.
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Citations
26 Claims
- 1. Apparatus for minimizing feedback to an acoustic to electric signal transducer of an acoustic signal derived from an electric to acoustic transducer comprising means responsive to an electric input signal derived from the acoustic to electric transducer for randomly shifting the phase of the electric input signal by an amount independent of any characteristic of the input signal to derive an electric audio signal having a phase randomly shifted relative to the phase of the input signal, and means responsive to the phase shifted electric audio signal for supplying the phase shifted electric audio signal to the electric to acoustic transducer.
- 7. In combination, acoustic-electric transducer means for deriving an audio, information bearing electric signal, means responsive to the electric signal for randomly shifting the phase of the electric signal by an amount independent of any characteristic of the information bearing electric signal, and an electric-acoustic transducer responsive to the randomly phase shifted electric signal, whereby the transducer derives an acoustic information signal that is not susceptible to acoustic feedback oscillations.
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18. Apparatus for minimizing feedback to an acoustic to electric signal transducer of an acoustic signal derived from an electric to acoustic transducer comprising means responsive to an electric input signal derived from the acoustic to electric transducer for randomly shifting the phase of the electric input signal to derive an electric audio signal having a phase randomly shifted relative to the phase of the input signal, and means responsive to the phase shifted electric audio signal for supplying the phase shifted electric audio signal to the electric to acoustic transducer, the random phase shifting means including a noise source having a pseudo-random code generator, and delay means for variably delaying the electric signal in response to the noise source.
- 19. Apparatus for minimizing feedback to an acoustic to electric signal transducer of an acoustic signal derived from an electric to acoustic transducer comprising means responsive to an electric input signal derived from the acoustic to electric transducer for randomly shifting the phase of the electric input signal to derive an electric audio signal having a phase randomly shifted relative to the phase shifted electric audio signal for supplying the phase shifted electric audio signal to the electric to acoustic transducer, the random phase shifting means includes a noise source having a pseudorandom code generator, and delay means for variably delaying the electric signal in response to the noise source, the delay means including a variable frequency oscillator having an output frequency controlled by the noise source.
Specification