Directional microphone
First Claim
1. A microphone assembly comprising:
- a housing having two outer input ports and an inner input port for admission of acoustic energy, the two outer input ports and the inner input port being arranged in predetermined spatial relationship to each other;
at least one microphone element housed in the housing;
at first acoustic transmission line, of a first predetermined length, for transporting acoustic energy entering one of the two outer input ports to a first position on the at least one microphone element;
a second acoustic transmission line, of a second predetermined length, for transporting acoustic energy entering the other of the two outer input ports to the first position on the at least one microphone element;
a third acoustic transmission line, of a third predetermined length, for transporting acoustic energy entering the inner input port to a second position on the at least one microphone element; and
a plurality of acoustic resistance elements, at least one acoustic resistance element being positioned in each of the acoustic transmission lines and the at least one acoustic resistance element being matched in specific acoustic resistance to the specific acoustic characteristic resistance of the respective acoustic transmission line.
6 Assignments
0 Petitions
Accused Products
Abstract
A monolithic second order gradient (SOG) microphone structure employs acoustic transmission lines wherein the acoustic phase delay along each of the acoustic transmission lines is in direct proportion to the length of each of the acoustic transmission lines and, where this is effected by the use of an acoustic impedance element placed within each acoustic transmission line that has an acoustic impedance related to the acoustic impedance of the associated acoustic transmission line. In one embodiment, the acoustic impedance element has a specific acoustic impedance substantially matched to the specific acoustic characteristic resistance of the acoustic transmission line. Various embodiments may utilize acoustic or electrical subtraction of the signals in the acoustic transmission lines to realize the desired directional sound pickup.
68 Citations
19 Claims
-
1. A microphone assembly comprising:
-
a housing having two outer input ports and an inner input port for admission of acoustic energy, the two outer input ports and the inner input port being arranged in predetermined spatial relationship to each other; at least one microphone element housed in the housing; at first acoustic transmission line, of a first predetermined length, for transporting acoustic energy entering one of the two outer input ports to a first position on the at least one microphone element; a second acoustic transmission line, of a second predetermined length, for transporting acoustic energy entering the other of the two outer input ports to the first position on the at least one microphone element; a third acoustic transmission line, of a third predetermined length, for transporting acoustic energy entering the inner input port to a second position on the at least one microphone element; and a plurality of acoustic resistance elements, at least one acoustic resistance element being positioned in each of the acoustic transmission lines and the at least one acoustic resistance element being matched in specific acoustic resistance to the specific acoustic characteristic resistance of the respective acoustic transmission line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
Specification