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Signal Processors

Signal Processors. Devices that change some characteristic of a sound. Analog Processors. ANALOG PROCESSORS DIRECTLY MODIFY SIGNALS AS THEY ENTER THE DEVICE . Digital Processors.

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Signal Processors

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  1. Signal Processors Devices that change some characteristic of a sound.

  2. Analog Processors • ANALOG PROCESSORS DIRECTLY MODIFY SIGNALS AS THEY ENTER THE DEVICE

  3. Digital Processors • DIGITAL PROCESSORS (DSPs) CONVERT THE INCOMING SIGNAL INTO BINARY LANGUAGE AND ARE THEN PROCESSED BY MATHEMATICALLY RECALCULATING THE DIGITAL CODE ACCORDING TO A ALGORITHM

  4. 4 Basic Categories of Processors • SPECTRUM PROCESSORS • TIME PROCESSORS • AMPLITUDE PROCESSORS • NOISE PROCESSORS

  5. SPECTRUM PROCESSORS • AFFECT THE SPECTRAL BALANCE (FREQUENCY/AMPLITUDE RESPONSE PATTERN ) • CHANGE TIMBRE • EXAMPLES: Equalizers and Filters

  6. TIME PROCESSORS • AFFECT THE TIME BETWEEN A SIGNAL AND ITS REPETITIONS • CHANGE ACOUSTIC ENVIRONMENT • EXAMPLES: Reverbs and Delays

  7. AMPLITUDE PROCESSORS • AFFECT THE DYNAMIC RANGE • CHANGE THE ACOUSTIC ENVELOPE • EXAMPLES: Compressors, Limiters, and Noise Gates

  8. NOISE PROCESSORS • REDUCE ANALOG TAPE HISS • EXAMPLES: Dolby and dBx

  9. EQUALIZATION (EQ) • PROCESS OF ALTERING THE FREQUENCY/AMPLITUDE RESPONSE PATTERN BY BOOSTING OR ATTENUATING SELECTED FREQUENCIES • THE MOST COMMON FORM OF SIGNAL PROCESSING • EQUALIZERS ENABLE US TO EXERCISE TONAL OR TIMBRAL CONTROL OVER A SOUND

  10. EQ USED FOR: • TO OVERCOME RECORDING DEFICIENCIES IN THE ROOM ACOUSTICS, MICROPHONE, OR INSTRUMENT • TO ALTER A SOUND FOR CREATIVE REASONS • TO AFFECT A BETTER BLEND BETWEEN COMPETING INSTRUMENTS

  11. BELL CURVE EQ • THE EFFECT OF EQ TO FREQUENCIES ADJACENT TO A TARGET FREQUENCY, ALSO CALLED A PEAKING CURVE EQ. BANDWIDTH: THE RANGE OF FREQUENCIES AFFECTED BY EQ ON EACH SIDE OF THE CENTER FREQUENCY

  12. QUALITY FACTOR (Q) • REFERS TO THE WIDTH OF THE AFFECTED BAND • HIGH Q VALUE = NARROW BANDWIDTH • LOW Q = WIDE BANDWIDTH

  13. SHELVING EQ • SIMILAR TO BELL CURVE EQ EXCEPT THAT THE CURVE GENTLY FLATTENS OUT INTO A STRAIGHT LINE

  14. EQUALIZERS • FIXED FREQUENCY (OR SELECTABLE FREQUENCY) HAS A SET NUMBER OF FREQUENCIES THAT CAN BE MODIFIED AND HAS A SET BANDWIDTH • PARAMETRIC HAS A "SWEEP-ABLE" OR CONTINUOUS FREQUENCY SELECT AND A BANDWIDTH THAT IS VARIABLE • GRAPHIC EQUALIZER IS A FIXED FREQUENCY EQUALIZER WITH FADER CONTROLS FOR EASY VISUAL INSPECTION

  15. FILTERS • DIFFER FROM EQUALIZERS IN TWO BASIC WAYS 1. THEY ONLY ATTENUATE (CUT) 2. THEIR EFFECT IS MUCH MORE DRASTIC

  16. HIGH PASS FILTER • HIGH PASS FILTERS ATTENUATE ALL FREQUENCIES BELOW A GIVEN FREQUENCY

  17. LOW PASS FILTER • LOW PASS FILTERS ATTENUATE ALL FREQUENCIES ABOVE A GIVEN FREQUENCY

  18. BAND PASS FILTER • BAND PASS FILTERS ATTENUATE ALL FREQUENCIES ABOVE AND BELOW TWO GIVEN FREQUENCIES

  19. NOTCH FILTER • NOTCH FILTERS ATTENUATE A VERY NARROW BANDWIDTH BETWEEN TWO FREQUENCIES

  20. REVERBERATION • SUCCESSIVELY REPEATING DELAYS CREATING CLOSELY SPACED ECHOES IS CALLED REVERBERATION OR REVERB • REVERB UNIT: A DEVICE THAT ARTIFICIALLY REPRODUCES THE SOUND CHARACTERISTICS OF DIFFERENT ACOUSTIC ENVIRONMENTS

  21. REVERB UNITS • ACOUSTIC ECHO CHAMBER • SPRING REVERB • PLATE REVERB • DIGITAL REVERB

  22. REVERB TERMS • DELAY: THE TIME BETWEEN REFLECTIONS OF SOUND • PRE-DELAY: THE TIME BETWEEN THE ORIGINAL SOUND AND ITS FIRST REPETITION • REVERB DECAY TIME: TIME IT TAKES SOUND TO DECREASE 60 dB

  23. DELAY UNITS • ANALOG DELAY USES PHYSICAL MEANS TO HOLD BACK A SIGNAL • DIGITAL DELAY SIMPLY CONVERTS SIGNAL (A/D CONVERTER), APPLIES A REVERB ALGORITHM AND THEN CONVERTS BACK TO ANALOG (D/A CONVERTER)

  24. COMPRESSORS • AN AMPLIFIER WHOSE OUTPUT HAS A SMALLER DYNAMIC RANGE THAN ITS INPUT • ALSO CALL A LEVELING AMPLIFIER • IT CONTROLS THE DYNAMIC RANGE

  25. LIMITERS • A COMPRESSOR WHOSE COMPRESSION RATIO EXCEEDS 11:1 • A COMPRESSOR WHOSE OUTPUT STAYS BELOW A PRE-SET LEVEL

  26. USES OF COMPRESSOR/LIMITERS 1. SMOOTH THE DYNAMIC RANGE 2. IMPROVE SPEECH INTELLIGIBILITY 3. IMPROVE S/N RATIO 4. CREATE THE EFFECT OF LOWERING AMPLITUDE

  27. EXPANDER • INCREASES THE DYNAMIC RANGE

  28. NOISE GATES • A DYNAMIC PROCESSOR THAT ALLOWS A SIGNAL TO PASS AT A PREDETERMINED POINT (THRESHOLD) BUT BLOCKS THOSE OF LESS AMPLITUDE • WORKS LIKE AN ON-OFF SWITCH FOR A MICROPHONE • DO NOT CONFUSE WITH NOISE PROCESSORS

  29. NOISE PROCESSORS • ONLY TASK IS TO REDUCE ANALOG TAPE HISS • USES A UNIQUE DEVICE CALLED A COMPANDER WHICH IS A COMBINATION COMPRESSOR AND EXPANDER

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