Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Thermal response to – or generation of – sound vibration
Patent
1995-04-10
1997-09-09
Tran, Sinh
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Thermal response to, or generation of, sound vibration
381155, 381 91, 381111, 381205, 181144, H04R 2500
Patent
active
056664338
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to sound receiving and sound reproduction apparatus.
BACKGROUND
One aspect of the invention relates to a microphone comprising a cylindrical transducer housing with a lateral axis and having a centre section and two end sections, the centre section having non-parallel, elliptical end faces oriented mirror-symmetrically with respect to a plane perpendicular to the lateral axis, the end sections having inner end faces confronting and parallel to respective ones of the centre section end faces, and microphone transducers mounted to receive sound from beween the respective end sections and the centre section.
Another aspect of the invention relates to a loudspeaker comprising:
a cylindrical, hollow housing with a lateral axis and having a centre section and two end sections, the centre section having non-parallel end faces oriented mirror-symmetrically with respect to a plane perpendicular to the axis, the end sections having inner end faces confronting and parallel to respective ones of the centre section end faces; and
four speaker transducers mounted in the housing, with two centre transducers in the centre section radiating towards respective ones of the end sections, and one end transducer in each of the end sections radiating towards the centre section, each transducer being sealed to the housing.
A microphone and a loudspeaker of these types are disclosed in EP-A-0 256 688 (CA-A-1 282 711, granted 9 Apr. 1991 to Raymond Wehner, the applicant in this application).
CA-A-1 060 350, granted 14 Aug. 1979, and EP-A-0 256 688, describe microphone and loudspeaker systems that are directed to the recording and open-air reproduction of sound fields so that the reproduced sound field includes the directional and range information from the originally recorded field for detection by the human hearing system. Microphones in these systems are intended to be analogs of the human hearing system, detecting the range and direction sound information that would be detected by the human hearing system. The loudspeaker aspect of the system exemplifies the Hamilton-Jacobi theory of wave movement.
The loudspeakers are intended to invert the detection process and to generate a sound field containing the direction and range information originally available.
SUMMARY
The present invention is concerned with certain improvements in the earlier systems.
According to one aspect of the present invention there is provided a microphone of the above described type that is characterized in that: the inner end faces of the end sections are imperforate; and only two microphone transducers are used, mounted centrally of the end faces of the center section.
This microphone retains the concept of converging sensing gaps or slots of the optimal shadow omniphonic microphone disclosed in EP-A-0 256 688, but uses only two transducers and solid baffles as the end sections. In use, the microphone is arranged with the end faces of the centre and end sections lying in planes that converge downwardly and to the front. The planes preferably intersect at the dihedral angle of a regular tetrahedron (70.degree. 32').
It is also preferred that the microphone housing is of circular cross-section so that the confronting end faces of the sections are elliptical.
The outer end faces of the housing are preferably parallel to the inner end faces of the respective end sections.
According to another aspect of the present invention there is provided a loudspeaker of the above type characterized by:
the end sections having closed outer ends;
baffle means extending across the centre section between the two centre transducers;
aperiodic chamber means; and
means communicating between the housing at the back side of each transducer and the aperiodic chamber means.
Each transducer thus radiates from an enclosure with a total air volume that includes the volume of the respective aperiodic chamber. The volume can be chosen to match the compliance and other characteristics of the transducer. The chamber is intended to
REFERENCES:
patent: 3995124 (1976-11-01), Gabr
patent: 4836326 (1989-06-01), Wehner
Battison Adrian D.
Thrift Murray E.
Tran Sinh
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