04644581 is referenced by 61 patents and cites 7 patents.

Headphones have a small cavity between the diaphragm and the ear canal with a microphone in the cavity closely adjacent to the diaphragm slightly off the axis of the ear canal and headphone diaphragm with the microphone membrane perpendicular to the headphone diaphragm. The microphone provides a feedback signal that is combined with the input electrical signal to be reproduced by the headphones to provide a combined signal that is power amplified for driving the diaphragm. The headphone transducer has a small 23 mm diameter diaphragm with a maximum excursion of 0.6 mm peak-to-peak and a low frequency resonance of 200 Hz. A disk of intracavity damping material inside the cavity isolates the microphone from the ear canal.

Title
Headphone with sound pressure sensing means
Application Number
6/749575
Publication Number
4644581
Application Date
June 27, 1985
Publication Date
February 17, 1987
Inventor
Roman Sapiejewski
Boston
MA, US
Agent
Charles Hieken
Assignee
Bose Corporation
MA, US
IPC
H04M 3/00
H04M 1/05
H04R 1/10
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