Ceramic microphones are a new version of crystal microphones. They are much more stable and widely shock-resistant, especially when compared to electromagnetic microphones. The operation of this type is fairly simple because it is based on a sound that can move a diaphragm. A bar or a pin connects this diaphragm to a piezoelectric material. In turn, the movement of the diaphragm causes a significant deformation in the piezoelectric material that generates a varying voltage. In other cases, when ceramic mics were used with transistor amplifiers, they had preamps that impulsed the microphones’s output signal and generated a low output impedance.
Ceramic Microphones: their Materials
The Most Common
The category for ceramic microphones is piezoelectric. The reason for this is that their transducer mechanism uses a special polarized ceramic material that provides an electrical potential. The most common polarized ceramic material is barium titanate.
Ceramic microphones tend to move as a result of vibration. This type of microphones have higher noise filter floors, as well as a limited high-frequency response, especially when compared to both capacitors and electret microphones. Dosimetry applications take advantage of these limitations due to their attractive properties. As additional information, ceramic mics are most common in type two instruments.
Less Common, but Still Used
Barium titanate is the most common material regarding ceramic microphones. Nevertheless, over time people began experimenting with other materials. For instance, people used lead titanium zirconate and Rochelle salt crystal. Regardless, the decision was to discard them eventually. To begin with, salt crystal wasn’t the optimal material because it wasn’t able to resist temperatures above 130º F. Also, moisture and humid environments damaged these crystals frequently. All things said and done, ceramic has been the chosen element for a long time, since it is able to tolerate high temperatures and extremely humid environments.
