A new hearing aid with built-in immunity to RF-interference was reported by one participant to show no reduction in the amount of interference heard compared to an older hearing aid when using telecoil coupling
Mic users experienced either no interference or less annoying interference on average than telecoil users
Even when mic users heard no interference, their ratings of speech understanding and usability differed to some degree across these interference-free phones.
Both mic and telecoil users tended to prefer listening on the digital cell phones at maximum volume, but this did not always achieve maximum listening comfort.