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A COMPARISON OF CONTACT MICROPHONE AND ELECTROGLOTTOGRAPH FOR THE MEASUREMENT OF VOCAL FUNDAMENTAL FREQUENCY

https://pubs.asha.org/doi/pdf/10.1044/jshr.2302.258?casa_token=b0JTostNoPUAAAAA:5WmfVZJ7gW4WeHxOjkjSRqySLUkJcNgQlzofvw-7GaGyxlBczh6lprP3pNDGo0X3KTX0IOpaEYw32EM

"An accelerometer microphone, henceforth called contact microphone, which is fastened to the neck below the larynx produces a signal related to the vocal fold vibrations and the sound pressure in the trachea."

"The waveform is reasonably independent of the articulation because of the high glottal impedance (Sundberg 1979)."

"Consequently, the waveform of a contact microphone signal is suitable for fundamental frequency measurements and frequently has been used for this purpose."

"The contact microphone (Special Instrument type BC-2) is a simple accelerometer containing a piezo-electric ceramic disc as the pick-up unit. The disc is enclosed in a metal container of 15 mm in diameter and 5 mm in thickness and weighs about 20 grams. A small pre-amplifier with high input impedance is placed close to the microphone along the connection wire in order to minimize hum."

"The fundamental frequency detector (Fonema type 00063) used for the contact microphone signal is of the dual-peak-sensing type."

"The positive and negative peaks in the input signal waveform trigger a bistable circuit, to generate a square-wave output which has the fundamental frequency of the vibrations sensed by the contact microphone."

Speech Pickup by at Head and Neck Contact Microphone Positions

https://pubs.asha.org/doi/pdf/10.1044/jshr.0203.277?casa_token=TdmgkGeTLy0AAAAA:PaE-2seKk7PvMVWs5pvUPWE0l-yirwB8-1YtFToR6W6M_DNstBP31HUlyFEOUOAV9Zlewd5wIdHGCb8"Contact microphones, either crystal or dynamic, may soon be available which will better meet service criteria for comfort, convenience of placement, and intelligibility in highlevel ambient noise."

"In certain military operations it would be desirable to pick up speech by a contact microphone from a source other than the front of the mouth for the following reasons: (a) in aircraft the microphone would not interfere with oxygen equipment; (b) the valve pops and breathing hisses of the oxygen equipment would not affect speech intelligibility; (c) the possibility of injuries to the mouth and teeth would be minimized when the pilot bails out of an aircraft at high speed; (d) in high noise levels, such as those in the vicinity of jet aircraft during ground operations, communicators would gain some advantage from observing lip movement; (e) certain pickup locations are better for noise shielding; for example, an ear canal microphone can be shielded by a helmet or by muffs and a helmet, and a contact microphone on the forehead or mandible by a helmet."

Paragraph

A contact microphone can also be known as an accelerometer microphone. This can be fastened below the larynx to produce a signal that is related to the vocal fold vibrations and the sound pressure in the trachea. The waveform produced by the contact microphone is usually independent on articulation. This is due to the high glottal impedance. The signal produced by the contact microphone measures fundamental frequency. The contact microphone is a simple accelerometer containing a piezo-electric ceramic disc as the pick-up unit. The disc is enclosed in a metal container of 15 mm in diameter and 5 mm in thickness and weighs about 20 grams. The military could really benefit from the contact microphone in multiple different ways. The ways the contact microphone could be beneficial are it would not interfere with oxygen equipment, wouldn't affect speech intelligibility, injuries to the mouth and teeth would minimize, could observe lip movement, and certain pick up locations are better for noise shielding.

Bibliography

https://pubs.asha.org/doi/pdf/10.1044/jshr.2302.258?casa_token=b0JTostNoPUAAAAA:5WmfVZJ7gW4WeHxOjkjSRqySLUkJcNgQlzofvw-7GaGyxlBczh6lprP3pNDGo0X3KTX0IOpaEYw32EM

https://pubs.asha.org/doi/pdf/10.1044/jshr.0203.277?casa_token=TdmgkGeTLy0AAAAA:PaE-2seKk7PvMVWs5pvUPWE0l-yirwB8-1YtFToR6W6M_DNstBP31HUlyFEOUOAV9Zlewd5wIdHGCb8