Georg-Erwin Arndt

Hearing aid with a directional microphone characteristic and method for producing same

In a method for producing a directional microphone characteristic and hearing aid device having a directional microphone characteristic, high-pass filters following two omnidirectional microphones are matched as to their limit frequencies for amplitude response and/or phase response of the two microphones. The limit frequency of the high-pass filter following one microphone is matched to the limit frequency of the other microphone.

Method and adapting a hearing aid, and hearing aid with a directional microphone arrangement for implementing the method

In a method for adapting a hearing aid, and a hearing aid arrangement for improving the directivity of a hearing aid with a number of microphones that are connected to one another for generating a directional characteristic, the hearing aid is exposed to acoustic waves in a room for precision measuring while the user is wearing it, and the directional characteristic is registered. The filter parameters that arise therefrom are supplied to parameterizable filters in the hearing aid that are connected downstream from the microphones, and the desired ideal directional characteristic can be approximated taking the individual conditions into account when the hearing aid is worn.

Hearing aid with an oscillation detector, and method for detecting feedback in a hearing aid

In a hearing aid having an oscillation detector and a method for establishing the presence of oscillations in a hearing aid, sinusoidal input signals of the microphone can be detected, and so oscillations that are present can also be detected. To this end, the number of digitized sample values in consecutive periods of the input signal is determined, and a long-term average value NL and a short-term average value NK are formed from these numbers. When NL and NK are essentially identical, the presence of oscillations is detected.

Measurement and visualization of three‐dimensional directivity pattern

In order to optimize a new second‐order multimicrophone technology for a KEMAR dummy head, a three‐dimensional directivity measurement setup was developed. To minimize mechanical mass and to reduce total measurement time a C‐Bow setup was used, containing 18 calibrated loudspeakers. Those small tweeters identical in construction are placed in every 10 deg of elevation in a semicircular arc of 2‐m diameter. The only moving part of this setup is a full‐circle rotating KEMAR. The ANSI Standard 3.35 for directional measurement is fully supported and the required 48 measuring points are completed in less than 3 min. Using this fast and simple setup, the various responses attained from different latitudes need to be weighted to calculate a three‐dimensional directivity value. Utilizing an equally distributed number, for example 400 measuring points easily executable with this setup, weighting can be omitted and a three‐dimensional plot with high resolution can be visualized. Additionally, two‐dimensional cuts o...