Wide Dynamic Range Compression (WDRC)
Wide dynamic range compression is a signal processing feature in digital hearing aids that automatically adjusts the amount of amplification applied based on the incoming sound level. The goal is to map a wide range of real-world sound levels into the reduced dynamic range that a person with sensorineural hearing loss can comfortably hear.
In a normal-functioning ear, the cochlear outer hair cells compress the dynamic range naturally, making soft sounds audible and loud sounds manageable. When hair cells are damaged, this natural compression is reduced. Loud sounds become uncomfortable at lower levels and the gap between what is audible and what is uncomfortably loud narrows. WDRC applies more gain to soft sounds (to make them audible) and less gain to loud sounds (to keep them within the comfortable range), approximating the function of a healthy cochlea.
Most modern digital hearing aids use WDRC across the frequency range of the device. The specific compression parameters (ratio, attack time, release time) are set by the audiologist during programming and adjusted based on the person's feedback and verified through real ear measurement.
