Dynamic Moving-coil Microphone Sound Transducer An example of a simple “Dynamic” microphone is shown below. Typical applications for microphones as a sound transducer include audio recording, reproduction, broadcasting as well as telephones, television, digital computer recording and body scanners, where ultrasound is used in medical applications. The most common types of microphones available as sound transducers are Dynamic, Electret Condenser, Ribbon and the newer Piezo-electric Crystal types.
Generally, the output signal from a microphone is an analogue signal either in the form of a voltage or current which is proportional to the actual sound wave. This signal is an “electrical image” representing the characteristics of the acoustic waveform. This is because it produces an electrical analogue output signal which is proportional to the “acoustic” sound wave acting upon its flexible diaphragm. The Microphone, also called a “mic”, is a sound transducer that can be classed as a “sound sensor”. Velocity – is the speed of sound through a transmission medium in m/s -1.Frequency – is the number of wavelengths per second in Hertz, ( ƒ).Wavelength – is the time period of one complete cycle in Seconds, ( λ).The relationship between wavelength, velocity and frequency is given below as: Sound Wave Relationship Both the sounds frequency and wave shape are determined by the origin or vibration that originally produced the sound but the velocity is dependent upon the medium of transmission (air, water etc.) that carries the sound wave. Sound is basically a waveform of energy that is produced by some form of a mechanical vibration such as a tuning fork, and which has a “frequency” determined by the origin of the sound for example, a bass drum has a low frequency sound while a cymbal has a higher frequency sound.Ī sound waveform has the same characteristics as that of an electrical waveform which are Wavelength ( λ), Frequency ( ƒ) and Velocity ( m/s). But in order for a sound transducer to either detect or produce “sound” we first need to understand what sound is. Sound transducers can also both detect and transmit sound waves and vibrations from very low frequencies called infra-sound up to very high frequencies called ultrasound. We tend to think of sound as only existing in the range of frequencies detectable by the human ear, from 20Hz up to 20kHz (a typical loudspeaker frequency response), but sound can also extend way beyond these ranges. Also, the actual sound need not be a continuous frequency sound wave such as a single tone or a musical note, but may be an acoustic wave made from a mechanical vibration, noise or even a single pulse of sound such as a “bang”.Īudio Sound Transducers include both input sensors, that convert sound into and electrical signal such as a microphone, and output actuators that convert the electrical signals back into sound such as a loudspeaker.
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