Patent
1974-07-12
1977-08-02
Claffy, Kathleen H.
H04R 2900
Patent
active
040397505
ABSTRACT:
Disclosed is a test system primarily designed for free field testing of the hearing of an individual utilizing phase modulation to reduce or eliminate the production of standing waves thereby permitting accurate determination of pure tone hearing acuity. The test system consists of an audio signal source which may be the continuous or pulsed sine wave output of an audiometer, audio frequency signal generator, audio oscillator, or tape recorder wherein said stimulus signal is applied to a phase modulator. The phase modulator may be either an electronic or mechanical device or any combination thereof for periodically shifting the phase of the stimulus signal a predetermined amount. The phase modulated signal may be applied directly to an acoustic transducer or transducers if of sufficient amplitude or it may be amplified by an audio amplifier or amplifiers prior to such application. The subject may also be biological organisms, an animal or a material wherein the invention disclosed accomplishes a test function other than that confined to hearing.
REFERENCES:
patent: 2489653 (1949-11-01), Leslie
patent: 2768236 (1956-10-01), Allison
patent: 2881393 (1959-04-01), Lacy
patent: 3119964 (1964-01-01), Crafts
patent: 3404235 (1968-10-01), Goldberg
TELEERA (English Edition) (Italy), No. 20, (Mar. 1969), E. Ferrarin, pp. 5-18.
Claffy Kathleen H.
Popek Joseph
Veeder David A.
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