There is a company that does exactly that only for audio recordings. 
They track the bias and derive the correct speed from that. Forgot their 
name. The demo is very convincing (as always).
Shai

On 20/12/11 17:39, Steven Smolian wrote:
> Electrical records have at least some hum in the 50-60 cycle range,
> depending on where it was recorded.
>
>
>
> Assuming a separate send that only contains audio below 70 hz from the
> source,
>
>
>
> has anyone experimented using Auto-tune to track this and/or other hums
> (condenser mikes, cutting heads, etc.) to establish the proper playing speed
> and to correct deviations therefrom?   If effective, this would hold true
> for 78s and mono LPs and tapes as well as stereo material.
>
>
>
> Steve Smolian
>