Hearing loss affects a wide range of the population and the nature of loss varies by individual. There isn't one cordless telephone that will be the best solution for every person with partial hearing loss. Many people with compromised hearing adapt by lip reading without being aware of it, so when this visual clue is removed, similar volume levels are no longer sufficient to transmit enough audible information, though sometimes a boost of specific frequencies can restore clarity.
Mainstream cordless phones are usually available with some control over the volume of the earpiece. For many with mild hearing loss, this may be enough. Different manufacturers and different models will produce varying results. Echo prevention circuitry prevents amplified earpiece audio from affecting sounds picked up at the mouthpiece in high-end phones. Telephones with amplifiers suitable for more advanced hearing loss are made by companies such as Clarity (clarityproducts.com), ClearSounds (clearsounds.com) and V-Tech (vtech.com).
Enhanced Clarity Phones
Wireless technology has improved over the past 20 years and digital signal processing helps further through features such as multiband compression. This helps accentuate the speech-definition frequencies, making it easier for a partially deaf user to distinguish nuance. The advantage of clarity processing is it may allow a user to understand clearly at low volume levels, with less risk to remaining hearing due to high sound pressure levels.
Extended Feature Phones
Many hearing-impaired users have difficulty hearing phones ring. Telephones designed for hard-of-hearing users will often include a variety of ring tones in different frequency ranges as well as bright lights to indicate incoming calls. As age-related hearing loss may be accompanied by vision and dexterity reductions, it is not unusual to find phones that include oversized number buttons to further assist users.
Teletype and voice carry-over phones now have cordless counterparts. Both services require special call-in services where the operator interfaces with the person being called. Teletype is used by a person with severe hearing loss and few voice skills. The hearing-impaired caller types input, and the operator types the response from the person being called. Voice carry-over systems are for late-deafened or other hard-of-hearing who have strong voice skills. The hearing-affected person speaks to the operator who types the responses from the hearing person being called.