Many people have never heard of them, but contact microphones are all around us in society. I sat down with an expert to figure out what they are and what they do.
Liane Morrissette is owner and founder of Cold Gold Audio, a company based in Nanaimo, British Columbia, that makes a wide range of contact microphones.
A contact microphone picks up vibrations through solid objects, unlike microphones singers use, which pick up sound through the air.
Contact microphones can be used for detecting leaks in plumbing, listening to the sounds inside an anthill, hearing hearts beating and blood flow, recording finger movements on musical instruments, amplifying the sound of tap dancers on stage, sensing traffic movement in the road and even protecting glass cases in jewellery stores by acting as an alarm trigger.
“A whole new world opens up when you get a contact mic.”
– Liane Morrissette, owner and founder of Cold Gold Audio.
How’s it work?
Contact microphones use piezoelectricity, the same principle at work when you hear things through your bones and teeth.
When materials such as bone, quartz crystals and some ceramics are stressed, a small voltage is produced. A contact microphone turns that vibration into piezoelectricity and sends it to an amplifier or recording device. All you need is a solid connection between the microphone and the object you wish to amplify.
How’s it made?
Cold Gold Audio makes contact microphones with specially selected piezoelectric discs. A length of cable attaches the disc on one end of the wire to an output plug on the other end.
PVDF film, a somewhat recent innovation, is a flexible polymer material that comes in a range of shapes and produces a more natural sound thanks to reduced self-resonance.
There are far more types of contact microphones than we can get into here. Visit www.contactmicrophones.com for an idea of the range.
Categories: How's it Work?