Synonyms
Microphone; Speech input device
Definition
Voice device in the context of biometrics is frequently used as a synonym for a simpler word: microphone. A microphone [1] is a transducer that converts sound (or, equivalently, air pressure variations) into electrical signals. There are many different types of microphones that use different methods to achieve this transduction, most of which will be revised in this entry. Besides the method employed to do the transduction, microphones are most frequently encapsulated, and the encapsulation allows to build microphones with different directional characteristics, which allow, for instance, to capture the voice coming from one direction and reject (to a certain extent) the noises or voices coming from other directions. Apart from the directionality, microphones also have different frequency responses, sensitivities, and dynamic ranges. All these characteristics can dramatically influence the performance of a speech biometric system and...