Loudspeaking telephone station including directional microphone
First Claim
1. A loudspeaking telephone station comprising:
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,characterized in that;
the polar response characteristic of the directional microphone includes a major lobe, one or more side lobes, and nulls between pairs of lobes, said major lobe having substantially greater amplitude than any of the side lobes;
the loudspeaker is positioned in the null of said polar response characteristic that resides between the major lobe and an adjacent side lobe;
the loudspeaker is aimed in a first direction and the microphone apparatus is positioned so that its major lobe is aimed in a second direction, said first and second directions being approximately orthogonal; and
the microphone apparatus comprises a first-order-gradient (FOG) microphone having sound ports on opposite sides of a common diaphragm that are separated by distance "d," the FOG microphone having a free field directivity pattern, D(θ
), given by;
##EQU2## where;
B>
1.
3 Assignments
0 Petitions
Accused Products
Abstract
A loudspeaking telephone station (speakerphone) includes a loudspeaker and one or more microphones within the same housing. The microphones are directional, each having a polar response characteristic that includes a major lobe, one or more side lobes, and nulls between pairs of lobes. The loudspeaker is positioned in the null of the polar response characteristic that resides between the major lobe and an adjacent side lobe. The microphone apparatus is positioned so that its major lobe is aimed in a direction that is generally perpendicular to the direction that the loudspeaker is aimed. Means are provided for increasing the distance between input sound ports of a first-order-gradient (FOG) microphone and thereby improving its sensitivity. A pair of such improved FOG microphones are used in assembling a second-order-gradient microphone. Full duplex operation is achieved when a pair of echo cancelers are added to further reduce the coupling between the transmit and receive directions of the speakerphone.
236 Citations
10 Claims
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1. A loudspeaking telephone station comprising:
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
characterized in that; the polar response characteristic of the directional microphone includes a major lobe, one or more side lobes, and nulls between pairs of lobes, said major lobe having substantially greater amplitude than any of the side lobes; the loudspeaker is positioned in the null of said polar response characteristic that resides between the major lobe and an adjacent side lobe; the loudspeaker is aimed in a first direction and the microphone apparatus is positioned so that its major lobe is aimed in a second direction, said first and second directions being approximately orthogonal; and the microphone apparatus comprises a first-order-gradient (FOG) microphone having sound ports on opposite sides of a common diaphragm that are separated by distance "d," the FOG microphone having a free field directivity pattern, D(θ
), given by;
##EQU2## where;
B>
1. - View Dependent Claims (2, 3, 4, 5)
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
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6. A loudspeaking telephone station comprising:
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
characterized in that; the polar response characteristic of the directional microphone includes a major lobe, one or more side lobes, and nulls between pairs of lobes, said major lobe having substantially greater amplitude than any of the side lobes; the loudspeaker is located at the center of the telephone station and positioned in the null of said polar response characteristic that resides between the major lobe and an adjacent side lobe; the loudspeaker is aimed in a first direction and the microphone apparatus is positioned so that its major lobe is aimed in a second direction, said first and second directions being approximately orthogonal; the microphone apparatus comprises four first-order-gradient (FOG) microphones that are positioned around an outside surface of the telephone station, each FOG microphone including sound ports on opposite sides of a common diaphragm that are separated by distance "d," and each FOG microphone is characterized by a free field directivity pattern, D(θ
), that is given by;
##EQU3## where;
B>
1.
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
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7. A loudspeaking telephone station comprising:
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
characterized in that; the polar response characteristic of the directional microphone includes a major lobe, one or more side lobes, and nulls between pairs of lobes, said major lobe having substantially greater amplitude than any of the side lobes; the loudspeaker is positioned in the null of said polar response characteristic that resides between the major lobe and an adjacent side lobe; the loudspeaker is aimed in a first direction and the microphone apparatus is positioned so that its major lobe is aimed in a second direction, said first and second directions being approximately orthogonal; and the microphone apparatus comprises three second-order-gradient (SOG) microphones that are positioned around an outside surface of the telephone station and, each SOG microphone comprising a pair of collinear first-order-gradient (FOG) microphones.
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
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8. A loudspeaking telephone station comprising:
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
characterized in that; the polar response characteristic of the directional microphone includes a major lobe, one or more side lobes, and nulls between pairs of lobes, said major lobe having substantially greater amplitude than any of the side lobes; the loudspeaker is positioned in the null of said polar response characteristic that resides between the major lobe and an adjacent side lobe; the loudspeaker is aimed in a first direction and the microphone apparatus is positioned so that its major lobe is aimed in a second direction, said first and second directions being approximately orthogonal; and the microphone apparatus comprises a pair of collinear first-order-gradient (FOG) microphones separated by distance d1, each FOG microphone generating an electrical signal that is connected to a different input of a subtracting circuit, one of the electrical signals being delayed by a time interval τ
;
whereby a second-order-gradient polar response characteristic is achieved. - View Dependent Claims (9, 10)
- microphone apparatus for converting audible sounds into electrical signals, a loudspeaker for converting electrical signals into audible sounds, and a speech network that electrically connects the microphone apparatus and the loudspeaker to a telephone line, the microphone apparatus having a directional polar response characteristic such that the microphone apparatus is more sensitive to sounds emanating from one direction than from other directions,
Specification