House Ear Institute

Minnesota Mining and Manufacturing Company

House Research Institute

Widex A/s

K/s Himpp

Sigfrid Daniel Soli

Shawn X Gao

Hsiang-Feg Chi

Chris L Johnson

Drew O'Connell

Chaoying Zhang

J Phil Mobley

Christopher Van Den Honert

Gregory P Widin

Morten Love Jepsen

Daniel J Freed

Hsiang Feg Chi

Sriram Jayaraman

Jean Sullivan

Ralph P Fravel

Kevin M Buckley

In a method of fitting a hearing aid system, a hearing aid user's hearing loss is classified and the hearing aid fitting is adapted in response to this classification. The hearing loss classification is, in one example, classified by determining an audiogram for the user, testing the user's hearing function under conditions that, for a user with that audiogram, would result in a predicted intelligibility, and comparing the measured intelligibility to the predicted intelligibility. Also disclosed is a hearing aid fitting system () adapted to carry out the method.

Method of fitting a hearing aid system and a hearing aid fitting system

An improved method for adaptively cancelling acoustic feedback in hearing aids and other audio amplification devices. Feedback cancellation is limited to a frequency band that encompasses all unstable frequencies. By limiting the bandwidth of the feedback cancellation signal, the distortion due to the adaptive filter is minimized and limited only to the unstable feedback regions. A relatively simple signal processing algorithm is used to produce highly effective results with minimal signal distortion.

Band-limited adaptive feedback canceller for hearing aids

A decorrelation method for improving feedback cancellation utilizes a small frequency shifting ratio, on the order of 0.3 percent. Frequency shifting is applied only to the high frequency portion of the signal, which is shifted alternately upward and downward.

Frequency shifter for use in adaptive feedback cancellers for hearing aids

An auditory prosthesis, and method, which is able to adapt better to filter out a selected unwanted portion of the auditory input signal by relying on a human activation, such as activation by the user, who knows by listening when the auditory environment contains only, or mostly only, the selected unwanted portion of the auditory input signal. This person may then activate the adaptive filter of the auditory prosthesis. The adaptive filter then utilizes the then current auditory environment as a noise reference on which to adapt. A transducer is adapted to receive the environmental sound and convert the environmental sound into an electrical input signal. The electrical input signal contains a selected electrical component corresponding to the selected auditory component in the environmental sound. An adaptive filter receives the electrical input signal and provides a filtered signal. The adaptive filter has adaptable filtering characteristics based upon a reference. The adaptive filter is operable in response to activation by the user to adapt the filtering characteristics using the electrical input signal as the reference to determine the filtering characteristics required to filter the selected electrical component from the electrical input signal. The filtered signal is received and converted to the auditory stimulus.

Auditory prosthesis for adaptively filtering selected auditory component by user activation and method for doing same

A 'true' hearing aid transfer function, including feedback, is derived from measurements taken with the hearing aid fitted in a patient's ear canal. Closed loop transfer functions are calculated at several hearing aid gains without opening the internal circuitry of the hearing aid using a time domain Weiner optimal filter model. The combined open loop transfer function of the hearing aid and feedback path is then calculated. Once the open loop transfer function is known, potentially unstable frequencies are identified and maximum hearing aid gain settings are determined. The hearing aid transfer function and transfer function of feedback path are also calculated from the closed loop transfer function measurements.

Method of measuring and preventing unstable feedback in hearing aids

A pressure regulating ear plug for regulating the rate of change of pressure inside an ear to minimize the pressure differential between the middle ear and a volume of the external ear cavity adjacent the ear drum is made of an ear plug adapted to fit tightly within the external ear cavity with no or minimal air leakage, and disposed within the ear plug is a pressure regulator with a slow leak rate. The pressure regulator is preferably made of a porous ceramic material.

Pressure-regulating ear plug

A noise and feedback suppression apparatus processes an audio input signal having both a desired component and an undesired component. When implemented so as to effect noise cancellation, the apparatus includes a first filter operatively coupled to the input signal. The first filter generates a focused reference signal by selectively passing an audio spectrum of the input signal which primarily contains the undesired component. The reference signal is supplied to an adaptive filter disposed to filter the input signal so as to provide an adaptive filter output signal. A combining network subtracts the adaptive filter output signal from the input signal to create an error signal. The noise suppression apparatus further includes a second filter for selectively passing to the adaptive filter an audio spectrum of the error signal substantially encompassing the spectrum of the undesired component of the input signal. This cancellation effectively removes the undesired component from the input signal without substantially affecting the desired component of the input signal. When the present apparatus is implemented so as to suppress feedback the adaptive filter output signal is employed to cancel a feedback component from the input signal.

Auditory prosthesis, noise suppression apparatus and feedback

The insertion effects of hearing aids are determined and compensated to restore the ability to have directional hearing in individuals wearing hearing aids. In one aspect a method involves finding the ratio of the unaided head related transfer function to the aided head related transfer function and then designing a hearing aid filter that is the inverse of that derived insertion effect, thereby restoring the ability to hear interaural differences in aided systems both in level and in time of arrival to improve hearing in the presence of noise. The insertion effects can be derived either through frequency domain analyses, using the above-mentioned transfer function calculations and measurements, or in another aspect through time domain analyses, using optimal filter calculations and measurement obtained using a successive data acquisition system that is subsequently time aligned by recording trigger pulses with the data.

Method of signal processing for maintaining directional hearing with

A multichannel signal processor for and an auditory prostheses utilizing such a signal processor having a plurality of filters each passing a different center frequency providing a set of filtered signals representative of the auditory content of the electrical input signal relative to its respective center frequency. A plurality of gating mechanisms individually coupled to the filter signals pass an output signal at a level above the perceptual level of the person when the filtered signal is above a predetermined level. The predetermined level is individually determined such that the output is past above the perceptual level only when the level of the filtered signal to which the gating means is coupled is likely to be among the larges of the filtered signals of all of the plurality of filters. Thus the multichannel signal processor in auditory prosthesis can have a combined stimulated signal which contains some, but not all, channels, namely those channels whose amplitude of signal is likely to rank among the highest compared to the amplitude of the remaining channels. In a preferred embodiment, such a channel dominant signal processor will help preserve periodicities created by sharply tuned band pass filters.

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Sierra Madre, CA, United States of America

Sigfrid Daniel Soli