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Microphones

Microphones. What is a Microphone?. Microphones are transducers , which means they convert one form of energy into another. They convert acoustical energy (sound waves) into electrical energy (audio signal).

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Microphones

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  1. Microphones

  2. What is a Microphone? • Microphones are transducers, which means they convert one form of energy into another. • They convert acoustical energy (sound waves) into electrical energy (audio signal). • To perform this function, all microphones have a thin membrane called a diaphragm, which mimics the function of the human ear (specifically eardrum)

  3. Classification of Microphones • Construction Characteristic: how they convert sound waves into an audio signal • Directionality: from what direction(s) the microphone best records sound • Frequency Response: What frequencies (low or high pitched sounds) the microphone records best

  4. Classification of Microphones • Physical Appearance: What the mic looks like • Hand held: Lavaliere: • Shotgun: Parabolic Dish

  5. Classification of Microphones • Physical Appearance: What the mic looks like • PZM (Pressure Zone Mic) • Boundary Mic (conference mic)

  6. Dynamic Microphones • The diaphragm is connected to wire, which is coiled around a magnet • As the diaphragm moves, the wire coil moves in the magnetic field • This movement creates the electrical current (audio signal) in the wire coil (This is the exact opposite of what a loudspeaker does. In fact, speakers and mics are constructed in much the same way.)

  7. Dynamic Microphones • PROS: • Versatile • Inexpensive, durable technology • CONS: • Not very sensitive: need fairly loud sounds to move the membrane • Don’t have flat (neutral) frequency response Electrovoice 635

  8. Condenser Microphones • Consist of two electrically charged plates, one of which acts as the diaphragm • As the sound waves move the diaphragm, the distance between the two plates changes, creating an electrical current (audio signal) in the attached wires

  9. Condenser Microphones:Pros & Cons • PROS: • More sensitive than dynamic mics • more neutral frequency response • CONS: • Require external power (battery or phantom power) • Not suitable for high volume applications: more prone to distortion Sennheiser ME 66 shotgun microphone

  10. Directionality & Pickup Patterns • Omnidirectional • Most accurate representation of a total environment • Sound picked up equally well from all directions • More prone to feedback (when sound from speakers is picked up by the mic in a loop, causing a loud squeal)

  11. Directionality / Pickup Patterns Cardioid( literally: “heart shaped”) • Rejects sound from behind the mic, with some pickup from the sides • Versatile, suitable for general use • Hypercardioid (“shot gun”) • Narrow, very directional pickup pattern directly in front of the mic (and, to some extent, behind) • Suitable for picking up sound over longer distances • Isolation can sound unnatural; subject must stay directly in front of the microphone

  12. Directionality / Pickup Patterns Bidirectional • Picks up sound from two opposite sides (figure eight) • Limited application possibilities (e.g. two people sitting across from each other with only one microphone available) • Variable Directionality • In some mics, pick up pattern can be adjusted.

  13. Frequency Response • How mic responds to different frequencies, high pitched (treble) versus low pitched (bass) sounds. • The F.R. of the mic used should be tailored to what is being recorded (e.g. human voice, specific instruments.

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