Allegretti & Witcoff, Ltd.
Hearing aid with improved noise discrimination
 A hearing aid that generally provides greater amplification for speech signals than noise signals. The hearing aid includes a microphone, variable highpass filter, transducer, and sensor assembly. The sensor assembly detects the amplitude of a band of low frequencies of the highpass filtered microphone signal, and provides a feedback signal to the variable filter to influence its cutoff frequency based on the characterisics of the highpass filtered microphone signal. The sensor also takes the time characteristics of the signal envelope into account, distinguishing between steady state noise-like signals and dynamically varying signals, such as speech. In response to loud, low frequency, substantially steady state signals, above a threshold amplitude, the sensor provides a feedback signal to the variable filter such that the cutoff frequency is raised. In response to softer, and/or higher frequency, and/or more dynamically amplitude varying signals, the cutoff frequency of the variable filter is raised less or left at a lower value. 
Beltone Electronics Corporation
H
H04R
inventional
James R.
Anderson