A contact microphone, also known as a piezo microphone, is a form of
microphone
A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...
that senses audio vibrations through contact with solid objects. Unlike normal air microphones, contact microphones are almost completely insensitive to air
vibrations but
transduce only structure-borne sound. Often used as
acoustic leakage probes, they also enjoy wide usage by
noise music artists experimenting with sound. Contact microphones can be used to amplify sound from acoustic musical instruments, to sense drum hits, for triggering electronic samples, and to record sound in challenging environments, such as underwater under high pressure.
Contact microphones based on
piezo materials are passive and high-impedance, and they sound
tinny without a matching
preamp.
The most commonly available contact microphone element is made of a thin piezoelectric ceramic round glued to a thin brass or alloy metal disc. This center disc is positively charged while the brass disc is negatively charged. The voltage can be measured across those parts and then amplified to produce sound.
See also
*
Throat microphone
A throat microphone, also called a laryngophone, is a type of contact microphone that absorbs vibrations directly from the wearer's throat by way of single or dual sensors worn against the neck. The sensors, called transducers, can pick up speec ...
References
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Microphones