Ion concentration differences across the basilar membrane create an electric potential.

Evidence

The scala media has a structure in its bony wall that leaks potassium ions (K+) into it. Thus, since the ion concentrations of liquids in the scala media and the scala tympani are different, a small electric potential difference exists across the basilar membrane. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 743

Categorization

• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 743