Directional microphone assembly

US6075869A · kind A · utility

Assignee

• ETYMOTIC RESEARCH, INC. · US

Inventors

• Mead C. Killion · Elk Grove Village, US
• Jonathan K. Stewart · Bloomingdale, US
• Don Wilson · Barrington, US
• Matthew Roberts · Munich, DE
• Steve Iseberg · Crystal Lake, US
• Timothy S. Monroe

Key dates

• Filing date: Oct 2, 1998
• Grant date: Jun 13, 2000
• Expiry date: Oct 2, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04R2410/07
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A microphone capsule for an in-the-ear hearing aid is disclosed. The capsule can include a top plate having first and second spaced openings defining front and rear sound inlets, and a directional microphone cartridge enclosing a diaphragm. The diaphragm is oriented generally perpendicular to the top plate and divides the directional microphone cartridge housing into a front chamber and a rear chamber. A front sound passage communicates between the front sound inlet and the front chamber, and a rear sound passage communicates between the rear sound inlet and the rear chamber. Front and rear acoustic damping resistors having different resistance values are associated with the front and rear sound passages. The acoustic resistor pair provides a selected time delay, such as about 4 microseconds, between the front and rear sound passages. The use of two acoustic resistors instead of one levels the frequency response, compared to the frequency response provided by a rear acoustic damping resistor alone.