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Recording the Voice

MICROPHONES. Recording the Voice. MICROPHONES. Vowels and Consonants. Vowels. Consonants. MICROPHONES. [MK; MSO CH]. INPUT ANALOG SIGNAL. ANTI-DISTORTION FILTERING. SAMPLE AND HOLD. (Linked to sampling rate and resolution ). Cutoff Frequency. (Amplitude). (Frequency).

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Recording the Voice

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  1. MICROPHONES Recording the Voice

  2. MICROPHONES Vowels and Consonants

  3. Vowels Consonants MICROPHONES [MK; MSO CH]

  4. INPUT ANALOG SIGNAL ANTI-DISTORTION FILTERING SAMPLE AND HOLD (Linked to sampling rate and resolution) Cutoff Frequency (Amplitude) (Frequency) ANALOG TO DIGITAL CONVERSION DATA STORAGE DIGITAL TO ANALOG CONVERSION DIGITAL AUDIO RECORDING (The voltage stream from a microphone, the line level stream from playback devices or keyboards passing through a mixer, etc.) (Required to eliminate aliasing - more on this in a moment) [Anti-aliasing low-pass filters used relative to the 1/2 sampling rate, to eliminate problematic high frequencies] (All frequencies above 1/2 sampling rate must be eliminated to avoid distortion.E.g. 25k Hz frequency distorts at 18 kHzat 44.1 kHz sampling rate:) (The stream of numbers created according to the sampling rate & resolution) (-3 k) (+3 k) 19 kHz 25 kHz (The crucual process of re-making the waveform from the stream of numbered samples, the quality and accuracy of which is linked to the sampling rate, resolution and other factors) (On hard drive, in live RAM memory or using other storage media) (The resulting analog electrical waveform) (The sound we hear through speakers or headphones)

  5. […when bouncing (rendering) audio, ProTools LE offers a wide variety of sampling rates, from ‘lo-fi’ 8kHz to ultra-high-end 192 kHz] (sound wave) (Stream of numbers according to sampling rate & digital resolution) DIGITAL AUDIO RECORDING …can be thought of as a series of ‘snapshots’ that the digital recorder takes of the sound wave… Sampling rate = # of digital ‘snapshots’ taken of the sound every second): Sample… [ProTools LE sessions (i.e. recording & editing) .can only be in 44.1 kHz or 48 kHz, however… Common sampling rates: 44.1 kHz (CD audio) 48 kHz (Video & DAT) 96 kHz (high-end digital recording) … & Hold

  6. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DIGITAL AUDIO RECORDING Sampling resolution = number range available for representing amplitude Because digital memory is built on switch-like binary bits, the resolution of each sample taken is determined by the bit rate of the digital recording: …1 bit provides a resolution of 2 binary numbers (0 or 1) …4 bits provide a resolution of 16 binary numbers (0-0-0-0; 0-0-0-1; 0-0-1-1; etc.) …8 bits (still heard in some digital samples on the Internet and in older video games) provide a resolution of 256 binary numbers… …16 bits (standard for CDs and most digital sound) provide a resolution of 65,536 binary numbers… …24 bits (now the industry standard for high fidelity sound recording & reproduction) provide a resolution of 16,777,216 binary numbers. [ProTools LE sessions.and rendering /bouncing can be in 8, 16 or 24-bit resolution]

  7. Location of the 1st sample Location of the 2nd sample Location of the 2nd sample Location of the 3rd sample DIGITAL AUDIO RECORDING In ProTools, the sampling process can be seen by zooming in to the highest level of a waveform, then selecting a single sample

  8. Next sample Location of the 3rd sample Location of the 4th sample ‘Zero-crossing’ sample DIGITAL AUDIO RECORDING

  9. Samples near the high end of the amplitude scale DIGITAL AUDIO RECORDING Samples near the low end of the amplitude scale

  10. INPUT ANALOG SIGNAL ANTI-DISTORTION FILTERING (via analog I/O) SAMPLE AND HOLD Important to understand that when you transfer minidisc recordings digitally in the sound lab, the stream of numbers recorded by the minidisc player is transferred directly into ProTools When sound data is transferred via the minidisc’s analog output, it enters ProTools as an input analog signal, and the whole process above begins again, often with some degradation in the signal The ProTools hardware then does the analog-to-digital conversion as / after editing is done ProTools INPUT ANALOG SIGNAL ANALOG TO DIGITAL CONVERSION DATA STORAGE DIGITAL TO ANALOG CONVERSION DIGITAL TO ANALOG CONVERSION ProTools DIGITAL AUDIO RECORDING Digital audio data transfer from minidisc:

  11. DIGITAL AUDIO RECORDING Compare this to the analog recording / reproduction technologies the preceded it: VINYL: (Later wax & vinyl records) In the earliest years of recording technology, sound was directly engraved on records (wax cyliders at first, then or harder wax records and eventually on vinyl). Notice the similarity to microphone technology in the use of a diaphragm. But instead of transducing the incoming sound waves into electrical energy, this system directly transmitted the mechanical energy of the signal to a stylus, which cut a groove in the wax or vinyl that was exactly analogous to the acoustic wave: The techology improved, but the idea remained essentially the same:

  12. DIGITAL AUDIO RECORDING TAPE: A much more complex technology invented by German scientists during WWII. Became important both for audio recording and data storage (mainframe computers, etc.) in the postwar era

  13. DIGITAL AUDIO RECORDING The playback head then picks up the magnetic duisturbance encoded on the tape, biases it down, and it issent to the output of the tape recorder before continuing on to anamplifier and loudspeakers to become acoustic sound again The essential idea is that the analog electrical signal from a microphone or mixer is biased (transposed, shifted) upwards into a supersonic range, then sent to the record head. At the high frequency, it disturbs the magnetic particles in one layer of the tape in a way analogous to the incoming wave (itself an analog representation of the original acoustic way picked up by the microphone)

  14. DIGITAL AUDIO RECORDING The main difference between analog and digital recordingis that a digital signal is always quantized — …made into a series of steps rather than a continuous wave before being converted back to a continuous analog wave that is played through loudspeakers. The more steps (samples) there are (the sampling rate)… …and the more levels available for those steps (the sampling resolution or bits)… …the more accurate the digital representation of the original sound.

  15. In-line effect Output (bypass -->) In-line effects Definition: An effect through which the signal on a track or mixer channel passes directly en route to the output The ‘raw’ signal is transformed by the effect, and cannot be heard as is unless the in-line effect is bypassed Signal

  16. Rack mounted effects devices, patched into a patch bay and routed through the mixing board Pedal or ‘stomp box’ external effects are patched directly from a guitar, keyboard or other electric instrument to a direct box, and then into the mixing console via patched connections. Pedals often require external noise reduction devices to make the processed signal they output usable in a mix. In-line effects In some situations (recording studios, film shoots) external effects units are still used. These are of two basic types: But most effects used today are sub-routines within digital audio editors called plug-ins

  17. Activate the insert by selecting it in the Inserts pull-down menu: Configure the insert in the panel that appears. If the panel is closed during your session and you want to readjust the settings, click on the small rectangle in the Inserts column to reopen it. In-line effects Inserts in ProTools: Available in the mixer or Edit windows; activate View > Edit Window Shows > Inserts View or View > Mix Window Shows > Inserts View to see the Inserts pull down menus.

  18. In-line effects Equalizers (EQ) Manipulation of the spectral color of a sound through phase cancelation (cut) or reinforcement (boost) within certain frequency bands EQ types: Rolloff / low-pass, high-pass filters Peak / dip (notch filter) Shelving Key points: Pro engineers and mixers always advise using EQ to CUT rather than BOOST frequencies. Eqs are not designed to act as effective preamps, which is what they do when they boost certain frequency bands. Usually you boost conservatively -- a few dB or so. But extreme EQ can sometimes work --experiment! Because of the way human hearing works, mid-range frequencies (which our ears are hypersensitive to) almost always have to be cut to avoid a ‘crowded’ feeling in mixes. Some examples of EQ use in music: To establish clear ‘frequency areas’ in the mix that don’t conflict and don’t mask other sounds To bring out the most characteristic part of a sound so that its presence in the mix is there without being overbearing, e.g. Electric piano <--> Electric guitar; Bass drum <--> Lower register bass Low toms <--> Upper register bass; Voice(s) <--> Synth, saxophone

  19. In-line effects Equalizers (EQ) ProTools EQ: 1 Band: offers several different EQ types: High Pass: below the set frequency in kHz, frequencies are attenuated by -12 dB per octave : Low Shelf: below the set frequency in kHz, frequencies are attenuated or boosted according to the gain setting in dB. Peak: a frequency band (the size of which varies according to the ‘Q’ setting, and the center of which is the set frequency in kHz) is boosted or cut according to the gain setting. High Shelf: above the set frequency in kHz, frequencies are attenuated or boosted according to the gain setting in dB. Low Pass: above the set frequency in kHz, frequencies are attenuated by -12 dB per octave Q = center frequency ÷ bandwidth Example: a center frequency of 1000 Hz (1.00 kHz) with a Q setting of 0.50 gives a bandwidth of 500 Hz (1000/x = 0.50; x = 500) What is the bandwidth when Q = 0.33? 1.00? 10?

  20. In-line effects Equalizers (EQ) 1 Low Shelf 2 Peak 1 High Shelf. ProTools EQ: 4 Band: offers a combination of EQ types: Common ProTools plug-in functions Input: the level of the incoming signal. Sometimes needs to be adjusted to avoid clipping. Bypass: suspends the activity of the plug-in Phase invert: flips the phase of the incoming signal if phase cancellation problems are heard Auto: opens up a panel in which different parameters can be chosen for automation. Once chosen, the ProTools track display pulldown will include the parameter in its list and graphic automation can be done in the Edit window.For real-time automation, access Window > Automation Enable and check that Plug-In automation is armed. Move sliders, buttons etc. on the plug-in panel and the automation will be recorded on the track. Safe: when active, prevents real-time automation from being recorded on the plug-in’s track. Settings: the lower left pop-up of a plug-in allows for saving, importing and management of personal presets.

  21. In-line effects Equalizers (EQ) ProTools EQ 3: redesigned for better graphics, but with the same essential functions: Demo 1

  22. In-line effects Equalizers (EQ) Chaining EQs: For extreme effects, EQs can be chained for more powerful processing. Each 4-band EQ added to the chain increases the amount of cut or gain in specific frequency ranges. Example: -48 dB cut in high and low frequencies (instead of max -12 dB):

  23. Oct 127.5-55 Hz Oct 3110-220 Hz Oct 5440-880 Hz Oct 71760-3520 Hz Oct 255-110 Hz Oct 4220-440 Hz Oct 6880-1760 Hz Oct 83520-4196 Hz In-line effects Equalizers (EQ) Know your frequencies!: Some examples of fundamental notes/sounds made by instruments and where the harmonic colors of the sound sit in the frequency spectrum: Freuqency ranges are placed in octaves using the full piano range as a reference. Each octave doubles in frequency as it rises.

  24. -2dB -2dB -6dB -6dB -10dB -10dB -14dB -14dB In-line effects Variable Gain Amplifiers 1. Compressors Definition: An automatic volume (a.k.a. ‘gain’, ‘level’, ‘amplitude’) control. Compressor/Limiters are the only signal processors generally used in recording, as a safeguard against distortion Works by reducing gain by a certain ratio when the signal goes above a set threshold Examples: A compressor with a ratio of 2:1 and a threshold of -10 dB will reduce a -2 dB signal at the input to -6 dB at the output (1/2 x 8 dB over threshold = 4 dB gain) No compression: -2 dB = -2 dB With compression (2:1 ratio & -10dB threshold): the -8 dB of gain is halved by the compressor (reduced by -4 dB) Compressed output is -6 dB

  25. In-line effects Variable Gain Amplifiers 1. Compressors ProTools Compressor: Compressor controls Gain: the level of the input sound. Can provide boost for weak signals, or cut for hot signals that might cause clipping Attack: how fast the compressor will kick in when the input signal goes over the threshold. Usually short, because the attack portion of a sound is typically the loudest and needs to be compressed right away. Release: how quickly the compressor will stop processing the incoming signal. Fast release times can produce a ‘pumping’ effect that sounds unnatural when there are many strong attacks. But fast releases can work well when there are only occasional high levels in the signal. A slow release will make the compression ‘linger’ such that the signal remains at a compressed level until the next attack occurs. But if the next attack is far away, an audible change in level is heard when the compressor kicks out. Knee: a further adjustment connected with the attack time of the compressor. Once compression kicks in after the attack time, the Knee controls the rate at which full compression is attained. 0 is the fastest (hardest) rate, and 200 the slowest (softest) rate.

  26. -2dB -2dB -6dB -6dB -10dB -10dB -14dB -14dB In-line effects Variable Gain Amplifiers 2. Limiters Definition: heavy compression (10:1 ratio or greater; ProTools’ default is 100:1). Severely cuts gain above the set threshold.. Much more obvious to the ear than compression. Often used as a ‘safety’ to prevent clipping above a certain limit, for broadcast signals, or for dynamically limited media like cassettes. Also used to reduce pops & clicks, Example:A compressor with a ratio of 100:1 and a threshold of -10 dB will reduce a -2 dB signal at the input to -10.08 dB at the output (1/100 x 8 dB over threshold = 0.08 gain ) No limiting: -2 dB = -2 dB With severe limiting (100:1 ratio & -10dB threshold): the -8 dB of gain is reduced to 1/100th of its size by the limiter Compressed output is -10.08 dB

  27. In-line effects Variable Gain Amplifiers 2. Limiters ProTools Limiter: Limiter controls : Gain: like the compressor, this controls the level of the input sound, boosting weak signals or cutting hot signals to prevent clipping. Threshold: the level above which limiting will be triggered Attack: how fast the hard limiter kicks in when the input signal goes over the threshold. Short for strong attacks, slower for sounds that build up. Release: how quickly the limiter stops processing the input signal. Fast release times produce a ‘pumping’ effect to be avoided when there are many strong attacks. Fast releases can work well with occasional high levels. Slow releases make the limiting ‘linger’ and keeps the signal at the reduced level until the next attack, so release times are usually short.

  28. In-line effects Variable Gain Amplifiers ProTools Compressor/Limiter 3: redesigned for better graphics, but with the same essential functions:

  29. -2dB -2dB -6dB -6dB -10dB -10dB -14dB -14dB In-line effects Variable Gain Amplifiers 3. Gates Definition: does the opposite of a limiter. When the signal falls below a set threshold, the level is abruptly cut to a specified level. Used to eliminate unwanted low level sounds in speech, music and other recordings.(e.g. to eliminate headphone or other leakage on music tracks). Also used for special effects like gated reverb With no limiting, the signal decays at a natural rate With severe limiting (100:1 ratio & -10dB threshold the gain is reduced dramatically (to 1/100th of the original) by the gate when the threshold is reached.

  30. In-line effects Variable Gain Amplifiers 3. Gates ProTools Gate: Gate controls : Threshold: the level below which the gate will kick in. Attack: Once a signal has gone below the threshold, the time it takes for gating to begin. Hold: determines the amount of time that the gate will remain closed once the signal has gone below the threshold (regardless of whether the signal goes above the threshold or not during that time. Decay: the rate at which the gate closes after a signal has gone below the threshold. Range: How much attenuation is applied when gating kicks in. The max is -80 dB, a total shutoff. Sometimes letting a bit of signal through is desirable (e.g. low amounts of leakage so the gating doesn’t sound too radically cut.

  31. -2dB -2dB -6dB -6dB -10dB -10dB -14dB -14dB In-line effects Variable Gain Amplifiers 4. Expanders Definition: does the opposite of a compressor. When the signal falls below a set threshold, the level is cut according to the set ratio. Also used to eliminate unwanted low level sounds in speech, music and other recordings, but somewhat more gently. Also used for special effects like gated reverb With no expander applied, the signal decays at a natural rate With an expander in-line using a 3:1 ratio, the signal decays three times more rapidly than the original once the threshold is reached.

  32. In-line effects Variable Gain Amplifiers 4. Expanders ProTools expander: Threshold: same as gate; the level below which the expander will kick in. Ratio:what distinguishes the expander from the gate; allows ‘gentler’ reduction once the signal passes below the threshold. But seems ineffective in ProTools. Attack:same as gate; once a signal has gone below the threshold, the time it takes for expanding to begin. Hold: same as gate; the amount of time that the expander will remain closed once the signal has gone below the threshold (regardless of whether the signal goes above the threshold or not during that time. Decay: same as gate; the rate at which the expander closes after a signal has gone below the threshold. Range: How much attenuation is applied when expansion kicks in. The max is again -80 dB, a total shutoff, but higher levels lets some signal remain.

  33. In-line effects Variable Gain Amplifiers ProTools Expander-Gate 3: redesigned for better graphics, but with the same essential functions:

  34. In-line effects Variable Gain Amplifiers 5. De-essers Definition: a limiter that is only applied within a set certain frequency range and at a set amplitude threshold. All frequencies in the range are sharply attenuated (ProTools default is 100:1). Normal use is to reduce the harshness of hard consonants (‘s’, ‘t’, ‘tch’, etc.) Typical frequency range for this purpose is 6-7 kHz and up. In the settings shown, as soon as a consonant above 7 kHz reaches 0 dB, sharp limiting will occur to those frequencies only.

  35. In-line effects Variable Gain Amplifiers ProTools De-esser 3: redesigned for better graphics, but with the same essential functions:

  36. Softest Loudest 20kHz 10kHz 5kHz 1kHz 500Hz 200Hz 20Hz LISTENING QUIZ PRACTICE A = Sound ??? (n.b.: time scales are not constant from example to example)

  37. Softest Loudest 20kHz 10kHz 5kHz 1kHz 500Hz 200Hz 20Hz LISTENING QUIZ PRACTICE B = Sound ??? (n.b.: time scales are not constant from example to example)

  38. Softest Loudest 20kHz 10kHz 5kHz 1kHz 500Hz 200Hz 20Hz LISTENING QUIZ PRACTICE C = Sound ??? (n.b.: time scales are not constant from example to example)

  39. Softest Loudest 20kHz 10kHz 5kHz 1kHz 500Hz 200Hz 20Hz LISTENING QUIZ PRACTICE D = Sound ??? (n.b.: time scales are not constant from example to example)

  40. LISTENING QUIZ PRACTICE A = Sound ??? (n.b.: time scales are not constant from example to example)

  41. LISTENING QUIZ PRACTICE B = Sound ??? (n.b.: time scales are not constant from example to example)

  42. LISTENING QUIZ PRACTICE C = Sound ??? (n.b.: time scales are not constant from example to example)

  43. LISTENING QUIZ PRACTICE D = Sound ??? (n.b.: time scales are not constant from example to example)

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