I’m sure I’ve come across similar requests. Is this the requirement for a specific e-book publisher or something?
The numbers alone are not enough unless we also know if that refers to the RMS level, Peak level, or something else.
Ah yes, Is this it? “Audible.com QC standard”
We are still not sure exactly what they mean in their specification, but perhaps there will be some useful suggestions in this topic: Audible.com QC standards