Wide Dynamic Range Compression

ReSound pioneered Wide Dynamic Range Compression (WDRC), the first amplification system ever to compensate for the loudness sensitivity that so often accompanies hearing loss.

Wide Dynamic Range Compression:

  • Makes soft sounds audible
  • Makes loud sounds comfortable
  • Provides a perfect balance between audibility and comfort
  • Is personalized for the individual’s hearing profile

Hearing loss and reduced dynamic range

People can no longer hear softer sounds when the hair cells in the inner-ear  responsible for amplifying them are damaged. But they continue to hear louder sounds in almost the same way as people with normal hearing. 

This phenomenon is known as reduced dynamic range. It means that different levels of sound must be amplified by different amounts in order to compensate for lost soft sounds without making louder sounds uncomfortable.

More gain for soft sounds, less for loud

Resound’s Wide Dynamic Range Compression applies progressively less gain as input levels increase. 

Compression parameters in the ReSound system are carefully selected to support compensation for abnormal loudness growth in a way that emulates results from studies of how compression works in the human cochlea. 

These include low, frequency-dependent compression kneepoints, compression ratios of up to 3:1, and syllabic time constants.

Little need for manual adjustment 

WDRC results in soft speech sounds being made audible, while louder sounds remain comfortable. Among other things, this means there is little need for hearing aid wearers to manually control the volume of their hearing aids, as louder sounds will not be amplified beyond tolerance levels. 

Without WDRC, some loud sounds that a normal hearing person would find tolerable could be distressing to a hearing aid wearer. For example a toilet flushing, someone shaking out a newspaper, or a child laughing on your lap.


ReSound Alera features the latest generation of Surround Sound by ReSound including Wide Dynamic Range Compression.

For more information, download Surround Sound by Resound - The Technical Background