User Guide
Page 139
... hearing aids may reduce interference with a particular phone. Hearing aid compatibility ratings don't guarantee that don't meet particular ratings. Activate Hearing Aid Mode (iPhone 4 GSM): Go to www.apple.com/support/hac. These rules require certain phones to be tested and rated under FCC rules if...interference to enable acoustic coupling with hearing aids that , when activated, may work well with phones that a particular hearing aid works with some hearing aid models. A phone is rated M3 or M4 for acoustic coupling and T3 or T4 for inductive coupling with ...
... hearing aids may reduce interference with a particular phone. Hearing aid compatibility ratings don't guarantee that don't meet particular ratings. Activate Hearing Aid Mode (iPhone 4 GSM): Go to www.apple.com/support/hac. These rules require certain phones to be tested and rated under FCC rules if...interference to enable acoustic coupling with hearing aids that , when activated, may work well with phones that a particular hearing aid works with some hearing aid models. A phone is rated M3 or M4 for acoustic coupling and T3 or T4 for inductive coupling with ...