School-college Physics Notes: SOUND 4. Health and safety issues
SOUND 4. Sound: health and safety issues of sound levels - precautions like ear defenders - decibel loudness scale, hearing frequency ranges of animals, use of microphone and loudspeaker
Doc Brown's Physics exam study revision notes
4. Sound: health and safety issues, hearing frequency ranges of animals, use of microphone and loudspeaker
4a. Sound and health and safety
4b. The frequency limits of hearing of some animals
TYPICAL FREQUENCY HEARING RANGES (Hertz, Hz)
Many animals can hear much higher frequency sounds than us humans.
Bats use high frequency echo location waves to sense the world around them.
Dolphins (and whales) use high frequency sound for communication.
4c. The microphone and loudspeaker
The diagram above illustrate the principle of a microphone e.g. for a vocalist or a telephone mouthpiece.
A microphone converts the energy of the pressure variation of sound waves into an electrical energy signal in an ac current.
The oscillation of the sound waves vibrates the diaphragm which generates an oscillating signal in the electrical circuit.
In some ways the effect is similar to how your ear works!
The electrical signal could in turn be used to re-generate sound in a loudspeaker.
In loudspeakers, an ac current conducting coil is moved by in a magnetic field to convert electrical energy into sound energy by way of a vibrating cone (diaphragm).
The cone vibrates the air and the oscillations produce the sound waves you hear.
For more details see the electricity and magnetism notes:
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