Transcript
Sound 1 -- Microphones
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Microphones
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Classification: Microphones are classified by:
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Classification: Microphones are classified by: – Operating Principle
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Classification: Microphones are classified by: – Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy?
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Classification: Microphones are classified by: – Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Directional Characteristic
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Classification: Microphones are classified by: – Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Directional Characteristic -- How does the microphone respond to sound arriving from different directions?
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy?
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo (piezo-electric)
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo – Dynamic
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo – Dynamic (moving coil)
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo – Dynamic – Ribbon
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo – Dynamic – Ribbon – Condenser Sound 1 -- Microphones
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Classification: Operating Principle -- What physical principle is used to convert mechanical energy into electrical energy? – Carbon – Piezo – Dynamic – Ribbon – Condenser (capacitor) Sound 1 -- Microphones
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Carbon Microphone:
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Carbon Microphone: The movement of the diaphragm compresses carbon granules, varying the electrical current.
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Carbon Microphone: Advantages:
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Carbon Microphone: Advantages: • Cheap to manufacture
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Carbon Microphone: Advantages: • Cheap to manufacture • Rugged
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Carbon Microphone: Advantages: • Cheap to manufacture • Rugged Disadvantages:
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Carbon Microphone: Advantages: • Cheap to manufacture • Rugged Disadvantages: • Requires external power source
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Carbon Microphone: Advantages: • Cheap to manufacture • Rugged Disadvantages: • Requires external power source • Limited frequency range
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Carbon Microphone: Advantages: • Cheap to manufacture • Rugged Disadvantages: • Requires external power source • Limited frequency range • Limited sensitivity
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Carbon Microphone:
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Piezo-electric Microphone:
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Piezo-electric Microphone: The movement of the diaphragm bends a crystalline materiel, varying the electrical current generated. (Same principle as a BBQ starter wand.)
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Piezo-electric Microphone: Advantages:
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Piezo-electric Microphone: Advantages: • Cheap to manufacture
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Piezo-electric Microphone: Advantages: • Cheap to manufacture Disadvantages:
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Piezo-electric Microphone: Advantages: • Cheap to manufacture Disadvantages: • Fragile
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Piezo-electric Microphone: Advantages: • Cheap to manufacture Disadvantages: • Fragile • High electrical impedance limits cable length
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Piezo-electric Microphone:
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Dynamic Microphone:
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Dynamic Microphone: The movement of the diaphragm causes a small coil of wire to move in a magnetic field, varying the electrical current generated. (Same principle as bicycle dynamo.) Sound 1 -- Microphones
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Dynamic Microphone: Advantages:
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Dynamic Microphone: Advantages: • Good quality for reasonable price
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Dynamic Microphone: Advantages: • Good quality for reasonable price Disadvantages:
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Dynamic Microphone: Advantages: • Good quality for reasonable price Disadvantages: • Susceptible to external magnetic fields (hum)
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Dynamic Microphone: Advantages: • Good quality for reasonable price Disadvantages: • Susceptible to external magnetic fields (hum) • Magnet is heavy
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Dynamic Microphone: Advantages: • Good quality for reasonable price Disadvantages: • Susceptible to external magnetic fields (hum) • Magnet is heavy • Magnetic shielding is heavy
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Dynamic Microphone: Advantages: • Good quality for reasonable price Disadvantages: • Susceptible to external magnetic fields (hum) • Magnet is heavy • Magnetic shielding is heavy • Inertia of coil limits sensitivity
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Dynamic Microphone:
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Ribbon Microphone:
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Ribbon Microphone: The movement of the ribbon within a magnetic field varies the electrical current generated.
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Ribbon Microphone: Advantages:
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Ribbon Microphone: Advantages: • Good high frequency response
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Ribbon Microphone: Advantages: • Good high frequency response Disadvantages:
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Ribbon Microphone: Advantages: • Good high frequency response Disadvantages: • Fragile to mechanical shock, wind, voice pops
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Ribbon Microphone: Advantages: • Good high frequency response Disadvantages: • Fragile to mechanical shock, wind, voice pops • Very low electrical impedance requires transformer
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Ribbon Microphone:
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Condenser Microphone:
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Condenser Microphone: The movement of the charged diaphragm causes a change in electrical capacitance, varying the electrical current generated.
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Condenser Microphone: Advantages:
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Condenser Microphone: Advantages: • Thin diaphragm is light
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity – good high frequency response
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity – good high frequency response • Can be made small
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity – good high frequency response • Can be made small Disadvantages:
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity – good high frequency response • Can be made small Disadvantages: • Requires external voltage source
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Condenser Microphone: Advantages: • Thin diaphragm is light – good sensitivity – good high frequency response • Can be made small Disadvantages: • Requires external voltage source • Expensive to manufacture Sound 1 -- Microphones
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Condenser Microphone:
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Directional Characteristics:
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Directional Characteristics: Omnidirectional
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Directional Characteristics: Omnidirectional • Not directional
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Directional Characteristics: Omnidirectional • Not directional • Diaphragm only exposed on one side (front)
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Directional Characteristics: Omnidirectional • Not directional • Diaphragm only exposed on one side (front) • Sensitive only to pressure variation
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Directional Characteristics: Omnidirectional • Not directional • Diaphragm only exposed on one side (front) • Sensitive only to absolute pressure variation • “Pressure microphone”
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Directional Characteristics: Bidirectional:
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Directional Characteristics: Bidirectional: • Directional
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Directional Characteristics: Bidirectional: • Directional • Diaphragm exposed on both sides (front and back)
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Directional Characteristics: Bidirectional: • Directional • Diaphragm exposed on both sides (front and back) • Sensitive to difference in pressure between front and back
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Directional Characteristics: Bidirectional: • Directional • Diaphragm exposed on both sides (front and back) • Sensitive to difference in pressure between front and back • “Pressure gradient microphone”
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Directional Characteristics: Bidirectional:
• Directional
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Directional Characteristics: Bidirectional:
• Directional – Responds to sound from front and back
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Directional Characteristics: Bidirectional:
• Directional – Responds to sound from front and back – Rejects sound from sides
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics:
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Directional Characteristics: Distance Factor:
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Directional Characteristics: Distance Factor: • Microphones with higher distance factor can work farther from source.
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Directional Characteristics: 3:1 Rule:
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Directional Characteristics: 3:1 Rule: • Microphones should never be placed closer together than three times the distance between mic and source.
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Directional Characteristics: 3:1 Rule: • Microphones should never be placed closer together than three times the distance between mic and source, to prevent comb-filtering.
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Proximity Effect:
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Proximity Effect: All directional microphones
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Proximity Effect: All directional microphones exhibit a boost in bass (low frequencies) when working close.
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Proximity Effect: All directional microphones exhibit a boost in bass (low frequencies) when working close.
2 feet
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Proximity Effect: All directional microphones exhibit a boost in bass (low frequencies) when working close.
2 inches
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Proximity Effect: All directional microphones exhibit a boost in bass (low frequencies) when working close.
¼ inch
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Boundary Effect:
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Boundary Effect: 1. Sound waves reflected from the floor or other surface cause phase cancellation at some frequency.
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Boundary Effect: 1. Sound waves reflected from the floor or other surface cause phase cancellation at some frequency. 2. The closer to a surface the microphone is mounted, the higher the frequency at which the phase cancellation takes place.
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Boundary Effect: 1. Sound waves reflected from the floor or other surface cause phase cancellation at some frequency. 2. The closer to a surface the microphone is mounted, the higher the frequency at which the phase cancellation takes place. 3. With the microphone mounted close to or directly on a large surface, any phase cancellation occurs at frequencies beyond the limit of hearing. Sound 1 -- Microphones
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Boundary Effect: Advantages of placing a microphone close to a large boundary:
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Boundary Effect: Advantages of placing a microphone close to a large boundary: • comb-filtering is inaudible
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Boundary Effect: Advantages of placing a microphone close to a large boundary: • comb-filtering is inaudible • doubling of SPL since direct and reflected sound waves add. (+6 dB)
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Boundary Effect: Advantages of placing a microphone close to a large boundary: • comb-filtering is inaudible • doubling of SPL since direct and reflected sound waves add. (+6 dB) • reverberation caused by surface eliminated at mic (direct to reverberant ratio improved by 3dB)
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Boundary Effect: Advantages of placing a microphone close to a large boundary: • comb-filtering is inaudible • doubling of SPL since direct and reflected sound waves add. (+6 dB) • reverberation caused by surface eliminated at mic (direct to reverberant ratio improved by 3dB – mic sounds closer) Sound 1 -- Microphones
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Boundary Effect: Advantages of placing a microphone close to a large boundary: • comb-filtering is inaudible • doubling of SPL since direct and reflected sound waves add. (+6 dB) • reverberation caused by surface eliminated at mic (direct to reverberant ratio improved by 3dB – mic sounds closer) • overall improvement of 9dB Sound 1 -- Microphones
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Boundary Effect:
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Microphone Inventory:
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Microphone Inventory:
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Microphone Inventory:
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Microphone Inventory:
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Microphone Inventory:
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