Synchronize device to audio stream - Approach
One problem with an acoustic link is frequency dependent multi-path fading/reinforcement, which can vary widely as the source and mic positions change, or as the room acoustic vary (moving hard objects, etc.)

So I might try a "click" that has a wide and known pattern of several non-harmonically related spectra, and check the Hamming distance between the transmitted and received spectral pattern peaks.

Use a non-harmonically related set of frequencies so that the harmonics of any clipped spectra will be mostly ignored (depending on window duration), and because multi-path fading can act as a comb filter notch.