Hearing aid reserve gain

If you’re trying a Phonak device, get your audiologist to you using Phonak Adaptive Digital Contrast. If you’re trying a Bernafon device fit using ‘envelope priority.’ These settings emphasize the envelope information in speech which often leads to better speech understanding that syllabic compression options used in most modern hearing aids for those with poor word recognition scores. Those with severe hearing loss or cognitive difficulties seem to be able to extract more speech information using this type of signal processing.

Thanks for your response.
How much headroom you recommend?
Thanks