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| - A microphone is essential for teachers who must project their voices in a noisy gymnasium or over music. The signal strength of your voice is reduced by six decibels (dB) every time you double the distance from the teacher to the students. For comparison, 0 dB is near total silence; a sound 10 times more powerful is 10 dB, and a sound 100 times more than 0 is 20 dB. Some common sounds and their decibel ratings include: near whisper (15 dB), normal conversation (60 dB), and a car horn (110 dB). Microphones are defined by the directional pattern in which they pick up sound. Three common types of microphones are unidirectional, bidirectional, and omnidirectional. The unidirectional microphone picks up sound from one direction, the bidirectional microphone picks up sound from two directions, a
- A microphone, sometimes called a mic (pronounced "mike"), is a device that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production and in radio and television broadcasting. The invention of a practical microphone was crucial to the early development of the telephone system. Emile Berliner invented the first microphone on March 4, 1877, but the first useful microphone was invented by Alexander Graham Bell. Many early developments in microphone design took place in Bell Laboratories.
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| abstract
| - A microphone is essential for teachers who must project their voices in a noisy gymnasium or over music. The signal strength of your voice is reduced by six decibels (dB) every time you double the distance from the teacher to the students. For comparison, 0 dB is near total silence; a sound 10 times more powerful is 10 dB, and a sound 100 times more than 0 is 20 dB. Some common sounds and their decibel ratings include: near whisper (15 dB), normal conversation (60 dB), and a car horn (110 dB). Microphones are defined by the directional pattern in which they pick up sound. Three common types of microphones are unidirectional, bidirectional, and omnidirectional. The unidirectional microphone picks up sound from one direction, the bidirectional microphone picks up sound from two directions, and the omnidirectional picks up sound from all directions. The type you select depends on your use of the microphone. A wireless headband microphone is a good choice for physical education, since it is lightweight and durable. Most of these microphones have a flexible gooseneck design that allows you to adjust the position of the mike. The microphone is attached to a small wireless transmitter that is worn on the waistband or connected to a headband. The teacher's voice is fed to the microphone receiver, which is connected to a receiver and then projected out into the gymnasium through the speaker. Wireless Microphone Systems transmit sound using VHF (very high frequency) or UHF (ultra high frequency) bands. The VHF band of frequencies is more crowded, and therefore makes VHF wireless microphone systems more susceptible to interference. The UHF wireless microphone systems, although slightly more expensive, will give you more reliable performance and are a better choice for physical education settings.
- A microphone, sometimes called a mic (pronounced "mike"), is a device that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production and in radio and television broadcasting. The invention of a practical microphone was crucial to the early development of the telephone system. Emile Berliner invented the first microphone on March 4, 1877, but the first useful microphone was invented by Alexander Graham Bell. Many early developments in microphone design took place in Bell Laboratories. In all microphones, sound waves (sound pressure) are translated into mechanical vibrations in a thin, flexible diaphragm. These sound vibrations are then converted by various methods into an electrical signal which varies in voltage amplitude and frequency in an analog of the original sound. For this reason, a microphone is an acoustic wave to voltage modulation transducer.
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