In consumer and pro-sumer products I never seen more than 19-20 clean
bits, being the remaining bits noisy. However "noisy" bits can carry
some information to be revealed with ad.hoc post processing (e.g.
reveal low frequency patterns or waves).
High resolution spectrograms can reveal acoustic components and
artifacts that are not audible. E.g. with MP3 recordings it is easy to
"see" the frames deleted by the compression algorithm because
considered not audible for the human ear.
This way you can also recognize the artifacts of compression in those
wav files created from MP3 or ATRAC files.
Gianni
2012/7/21, sainganrob <>:
>
>
> --- In "Avocet" <> wrote:
>>
>
>> I haven't looked at 24 bit recordings on my affordable Tascams, but I
>> suspect that the least bits are noisy. For a start, no analogue input
>> is likely to have a signal to noise ratio of 138dB if only because
>> that takes it beyond thermal noise.
>>
>
> Not quite, remember, signals go above reference levels as well as below :=
)
>
> A 150R, 20KHz BW, 20 degC source at a nominal 'Line Level' peak of +8dB r=
e
> (0.775) is 139dB SNR.
>
> A typical clip point for a Line Input stage is +20dB and so would equate =
to
> a 151dB SNR.
>
> As the chances of receiving a +20dB (or +8dB for that matter) signal with
> nothing but thermal noise are extremely small, I think its safe to assume
> the Tascam's least bits will be noisy :)
>
> Rob
>
>
>
>
>
--
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