Audio and signal processing - unsorted stuff: Difference between revisions
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==Semi-sorted== | ==Semi-sorted== | ||
===Performance metrics=== | ===Performance metrics=== | ||
====THD and THD+N==== | |||
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some ADC-specific: | some ADC-specific: | ||
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As such, below 0.01% is measurable but inaudible so good enough for most use, and lower is better. | As such, below 0.01% is measurable but inaudible so good enough for most use, and lower is better. | ||
The THD of even good amps, take =0.08%, is only a little over -60dB away (1% is 40dB, 0.1% is 60dB, 0.01 is 80dB) | |||
This seems to be why these are typically given in percent | |||
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====SINAD==== | |||
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SINAD: Signal-to-Noise And Distortion; the combination of SNR and THD | SINAD: Signal-to-Noise And Distortion; the combination of SNR and THD | ||
20 * log ([Fundamental] / SQRT (SUM (SQR([Noise + Harmonics])))) | 20 * log ([Fundamental] / SQRT (SUM (SQR([Noise + Harmonics])))) | ||
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====Other metrics==== | |||
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ENOB: Effective Number Of Bits | ENOB: Effective Number Of Bits | ||
(SINAD – 1.76) / 6.02 | (SINAD – 1.76) / 6.02 |
Revision as of 12:52, 9 April 2024
Speech analysis and processing
Source-filter model
Vocoders
Voice coders analyses speech into parameeters, then synthesizes based on those parameters.
They were once made with the idea to parametrize speech for efficient transmission.
It was an important development in telecom, and also used in phonetics.
It was also potentially an instrument of sorts. A voder is the production part only, and sometimes is even a playable machine[1].
These days vocoders are mostly used to distort vocals and instruments in music.
See also:
- http://en.wikipedia.org/wiki/Vocoder
- http://en.wikipedia.org/wiki/Envelope_follower
- http://en.wikipedia.org/wiki/Phase_vocoder