DR. DEREK R ALLEN, M.D.
Osteopathic Medicine at Superior Ave, Newport Beach, CA

4569413, Feb 11, 1986

May 9, 1983

6/492741

Derek R. Allen - Newport Beach CA

A61B 702

181131

A stethoscope is provided which includes a stethoscope head and a pair of ear tips which are connected by tube means which provide individually separate air passages from the stethoscope head to the ear tips. The length of each of the air passages is selected such that the resonant peaks of sound transmitted from the stethoscope head to one ear lie in the resonant valleys of sound transmitted from the stethoscope head to the other ear. This is achieved by utilizing separate air passages which have a length ratio in the range of about 0. 63 to about 0. 73. The stethoscope is preferably utilized in conjunction with a dual stethoscope head having a bell receiver for transmitting low frequency sounds and a diaphragm receiver for transmitting high frequency sounds.

5498841, Mar 12, 1996

Mar 10, 1995

8/401956

Derek R. Allen - Newport Beach CA

H04R 2500

181137

A stethoscope head having a first pair of acoustical passages in sound communication with a low frequency sound receiving bell and a second pair of acoustical passages in sound communication with a high frequency sound receiving diaphragm. A cylindrical valve plug having a third pair of acoustical passages is disposed within a cylindrical bore into which the first and second pairs of acoustical passages open. A pair of sound tubes are connected to the third acoustical passages within the cylindrical valve plug. The pair of sound tubes act as a lever to facilitate rotation of the cylindrical valve plug to acoustically connect the third acoustical passages with either the first or second pair of acoustical passages.