Outer hair cells of the mammalian cochlea are part of an amplification system that enhances incoming sound. Pharmacological manipulations, a wide range of genetic mutations, the anatomical positioning of the cells and a fast voltage driven motility all provide evidence for involvement in cochlear tuning. It has long been proposed that OHCs can provide a force term that compensates the dynamics for any viscous damping of the basilar membrane. However, the (RC) low pass filtering of potential by the OHC membrane appears to limit the frequency at which potential driven ‘electromotility’ could contribute to cochlear mechanical tuning. Limiting OHC motile bandwidths have also been emphasized by recent in vivo optical coherence tomography (OCT) measurements and by in vitro patch clamp recording of isolated cells.  To explain these data, considerations based on piezo electric descriptions of the OHCs (Iwasa, 2017, Rabbitt, 2020)  suggest that the OHC membrane capacitance can be a source of power up to high acoustic frequencies.
The simplest theoretical models of the cochlear partition are those where, at each point, the OHCs provide feedback to the basilar (BM) and tectorial (TM) membranes, both of which can be resonant structures (Geisler, 1993). For a complete description, point models should be coupled into longitudinal cochlear modes to include wave propagation in the fluids; and ideally the models should be solved in the time domain to allow the incorporation of known non-linearities. The number of indeterminate parameters in such schemes can render these models prohibitively complex.
To clarify such proposals biophysically,  I have constructed cochlear models that incorporate the inward current arising from the anion movement associated with deformation of the OHC motor protein prestin/SLC26A5 (Gale & Ashmore, 1994). This current is not limited by the RC low pass filter and can dominate the OHC current balance at high frequencies, extending the OHC operating bandwidth. Simple considerations indicate that the resulting OHC forces behave like positive feedback at low frequencies, but enhance any resonance of the BM (and of the TM) at high frequencies, producing a sharp resonance even though the transducer current is not primarily driving prestin/SLC26A5.  Such modelling results may also explain qualitatively distinct auditory nerve frequency tuning curves observed at high and at low best frequencies. .