Digital wireless telephones sometimes cause interference because of electromagnetic energy emitted by the telephone’s antenna, backlight, or other components. Therefore, the Federal Communications Commission has adopted specific hearing aid compatibility rules for digital wireless telephones.

 

The standard for compatibility of digital wireless phones with hearing aids is set forth in American National Standard Institute (ANSI) standard C63.19. ANSI C63.19 contains two sets of standards: an “M” rating (originally a “U” rating) from one to four for reduced radio frequency (RF) interference to enable acoustic coupling with hearing aids that do not operate in telecoil mode, and a “T” rating (originally a “UT” rating) from one to four to enable inductive coupling with hearing aids operating in telecoil mode. A digital wireless handset is considered hearing aid-compatible for acoustic coupling if it meets an “M3” (or “U3”) rating under the ANSI standard. A digital wireless handset is considered hearing aid-compatible for inductive coupling if it meets a “T3” (or “U3T”) rating under the ANSI standard.

 

In addition to rating wireless phones, the ANSI standard also provides a methodology for rating hearing aids from M1 to M4, with M1 being the least immune to RF interference and M4 the most immune. To determine whether a particular digital wireless telephone is likely to interfere with a particular hearing aid, the immunity rating of the hearing aid is added to the rating of the telephone. A sum of four would indicate that the telephone is usable; a sum of five would indicate that the telephone would provide normal use; and a sum of six or greater would indicate that the telephone would provide excellent performance with that hearing aid.

 

A listing of Acer’s handset HAC by current and recently offered models can be found in the table below.