# US 4,400,805 A · Acoustically filtered transducer

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- Number: US 4,400,805 A
- Document ID: US4400805A
- Status: Granted
- Kind: A
- Application number: 06/257,840
- Filed: 1981-04-27
- Granted: 1983-08-23
- Earliest claimed: 1981-04-27
- Assignees: Rockwell International Corporation
- Inventors: Harry Nadler
- Web page: https://patentgrep.com/patent/US4400805A

## CPC

- G10K 11/04: Acoustic filters {; Acoustic resonators}
- G01S 1/72: using ultrasonic, sonic or infrasonic waves
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

Disclosed is an acoustic transducer which includes a pressure tight vessel with a window in the vessel which is transparent to acoustic wave energy. A gas is disposed within the vessel, while an electromechanical transducer is located within the vessel at an antinode for a resonant wave of the gas. A port communicates with the interior of the vessel, with a pressure control coupled to the port and to a source of the gas for controlling the pressure of the fluid within the vessel.

## Claims

### Claim 1

An acoustic transducer, comprising:
a pressure tight vessel;
a compressible fluid disposed within said vessel;
an electromechanical transducer disposed within said vessel at an antinode of a characteristic resonance pattern for said fluid within said vessel; and
a port communicating with the interior of said vessel for changing the pressure of said fluid within said vessel.

### Claim 2 (depends on 1)

The transducer of claim 1, further comprising an acoustically transparent window in said vessel for admitting acoustic wave energy therein.

### Claim 3 (depends on 2)

The transducer of claim 2, wherein said fluid further comprises a gaseous fluid.

### Claim 4 (depends on 3)

The transducer of claim 3, further comprising a source of said fluid and a pressure control coupled to said port and said source for controlling the pressure of said fluid within said vessel.

### Claim 5

An acoustic transducer, comprising:
a pressure tight vessel;
an acoustically transparent window in said vessel;
a gas disposed within said vessel;
an electromechanical transducer disposed within said vessel at an antinode for a resonant wave of said gas within said vessel;
a port communicating with the interior of said vessel; and
a pressure control coupled to said port and to a source of said gas for controlling the pressure of said fluid within said vessel.

### Claim 6

A method of converting acoustic wave energy to an electrical signal, comprising the steps of:
placing an electromechanical transducer within a pressure tight vessel at an antinode of a resonant wave, and
pressurizing the vessel to achieve a resonance at a predetermined acoustic wave frequency.