Comments by "Siana Gearz" (@SianaGearz) on "The Rapid Start (u0026 End) of the CD" video.

@ScottGrammer Fun fact, even people with extended range hearing cannot differentiate frequencies above about 16.5-17KHz from each other. They all just sound the same. You can even induce ultrasonic hearing with bone conduction in most people, reaching maybe around 50KHz, and they still won't be able to tell the difference. There is also sort quite little acoustic energy up there.
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@trudyandgeorge actually a fair number of circuits support automatic output muting to gnd; and some others have enough precision to actually drive very low magnitude signals quite precisely, though that's actually trickier. However you also have quantisation noise, from the discrete amplitude values that can be recorded. This noise overlays all sound, and for a CD, it's at a magnitude of about -96 or -98dB, i forget which marks the nominal dynamic range. But we have noise shape dithering, which shifts this quantisation noise into a band where hearing sensitivity is lower, up in the frequency range, and keeping it out of the sensitive midrange. So the perceived dynamic range of CD is actually larger than the nominal figure. Various values have been suggested where one should stop chasing extra equipment fidelity, usually about -99 to maybe -110 dB noise and distortion in midrange. Pain threshold is generally around 120dB but you have to consider that you're not in a noise free environment, hearing threshold is 0dB but a quiet room is around 25dB environment noise. If you wear headphones to block it out, your hear your blood vessels making noise. Music is usually mastered for 80-85dB average listening level, with it being perhaps 10-15dB below peak amplitude, more for classical. Even -80dB noise floor can appear quite inoffensive, usually hidden, if not quite ideal.
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