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RE: To Dither or Not to Dither? J. River/PonoMusic World

Your analysis does not take into account the necessity for headroom when making digital recordings. For classical music orchestral recordings this is typically 18 - 30 dB, comparing RMS levels with peak samples. In addition, for live recordings that are not normalized (just what came from the ADC) there is the need to keep a few extra dB of headroom that is otherwise wasted in case the musicians play louder than expected.

I have one recording that, were I to attempt to reproduce it at live volume, would result in audible dither noise. It is an uncompressed 24 bit recording of a Space Shuttle launch taken at the VIP booth. If adjusted so that the "ten, nine, eight,...." is at 70 dB at my listening position the launch SPL is 140 dB at 15 Hz. (According to Bob Katz who made the recording.)

There are other less extreme examples producing such high signal peaks, such as Arny Kruger's key jangling test. This has energy all the way up to 48 kHz on a 96/24 recording and for natural volume level requires a gain setting about 10 dB louder than I use for a Mahler symphony, even through the keys aren't loud. The peak to RMS ratio on this recording is 26 dB.

Also, note that the threshold of hearing at some frequencies is below 0 dB. It is right at the thermal motion of molecules against an ear drum.

Your arguments neglect many factors that can add up to 30 dB. Notice that in a live concert situation, one will hear a dynamic range of over 120 dB. The dynamic range of a full orchestral tutti to a solo violin can be 55 dB or more, however one then can listen to a note decay due to hall reverberations, right down to the listener's threshold of hearing.
Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

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