Directional microphone assembly

• US 4,528,426 A
• Filed: 11/25/1983
• Issued: 07/09/1985
• Est. Priority Date: 11/23/1983
• Status: Expired due to Term

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Lafrance, Conrad D., Fatovic, Peter
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): Byrd, Danita R.
• Application Number:
  US06/555,139
• Time in Patent Office: 592 Days
• Field of Search: 179/121 D, 179/178, 179/179, 179/180, 181/151, 181/196, 181/178, 181/199, 381/87, 381/88
• US Class Current: 381/357
• CPC Class Codes: H04R 1/222 for microphones H04R1/24, H04R1/26 take precedence
• CPC Class Codes: H04R 1/326 for microphones H04R1/34 and H04R1/40 take precedence

Abstract

A directional microphone assembly in which an electroacoustic transducer housed in a capsule, having a directional response characteristic, is mounted in the assembly housing and surrounded by an acoustically transparent foam covering. As a result acoustic waves reflected off surfaces of the housing are dispersed so as to minimize the effect of the surfaces on the directional response characteristic.

Claims

1. A microphone assembly comprising:

an electroacoustic transducer, housed in a capsule having a forward facing opening and a plurality of sideward facing openings spaced around the perimeter of the capsule, said openings coacting with the electroacoustic transducer to provide a preselected free-field directional response characteristic;

the capsule being surrounded and supported on at least the perimeter by an acoustically transparent foam covering which overlays the openings, and which disperses acoustic waves passing therethrough;

the covering containing the capsule being mounted in a housing contiguous to an acoustically reflecting surface of the housing so that some of the sideward facing openings receive acoustic waves reflected from said reflecting surface, whereby the foam covering disperses the acoustic waves reflected from the surface so as to minimize the effect of the surface on the free-field directional response characteristic.

2. A microphone assembly as defined in claim 1 in which said capsule is cylindrical in shape, the forward facing opening is in one end and the sideward facing openings are around the cylindrical surface of the capsule.

3. A microphone assembly as defined in claim 2 in which the foam covering is supported in an exterior corner of the housing against an arcuate shaped acoustically reflecting surface so that at least some of the sideward facing openings are facing said surface;

and which additionally includes an open frame which together with the reflecting surface surrounds and supports the acoustically transparent foam covering containing the capsule.

4. A microphone assembly as defined in claim 1 in which the preselected free-field directional response characteristic is a cardioid pattern in the direction of the forward facing opening.