[54] HEARING AID
[75] Inventor: Henning Haugaard Andersen,
H0rsholm, Denmark
[73] Assignee: T0pholm & Westermann ApS,
Vaerloese, Denmark
[21] Appl. No.: 836,260
[22] PCT Filed: May 29, 1995
[86] PCT No.: PCT/EP95/02033
§ 371 Date: May 9, 1997
§ 102(e) Date: May 9, 1997 [87] PCT Pub. No.: W096/17493
PCT Pub. Date: Jun. 6, 1996
[30] Foreign Application Priority Data
Nov. 26, 1994 [DE] Germany 44 41 996.1
[51] Int. C I. H04R 25/00
[52] U.S. CI 381/312; 381/318; 381/320
[58] Field of Search 381/23.1, 60, 68,
381/68.2, 68.4, 68.6, 68.7, 68.3, 68.5, 312, 314, 317, 318, 320, 321, 323
[56] References Cited
U.S. PATENT DOCUMENTS
4,471,171 9/1984 Kopke et al 381/60
A hearing aid includes a microphone (1), a signaltransmission unit (2,3,) for forming or otherwise processing the signal, an output amplifier (4) to which an earphone (10) is connected, and a battery as the power supply. The output amplifier (4) is implemented essentially as a 2-A amplifier and is connected to a pulse generator (8) which produces a high-frequency pulsed clock signal in the 1 MHz region. A series-connected low-pass filter (15) is also provided. The input signal to the signal converter is a representation, produced by signal processing in the transmission unit, ol the low-frequency input signal to the hearing aid, this signal being converted in the signal converter into a binary signal. The output signal (14) thus appears, after passing through the low-pass filter, essentially as an amplified copy of the low-frequency input signal.
5 Claims, 3 Drawing Sheets
