Cell Phone Hearing Aid Compatibility
If you have family members or patients who use hearing aids, you may know that they often have trouble using cell phones. Some cell phones cause radiofrequency interference with hearing aids, so the user hears high-pitched whistling sounds through the hearing aid, or static, or thumping sounds. But all cell phones aren't alike in this respect.
Some phones have lower radiofrequency emissions or different technology that can reduce the unwanted effects on hearing aids. So you should advise hearing aid wearers shopping for a hearing aid compatible cell phone to try several brands and models before they decide. The more immune your hearing aid is to radiofrequency interference, the less likely you are to experience interference noise from wireless devices.
Hearing aid wearers should always ask cell phone carriers what the emissions ratings are for any new phone being considered for purchase, and cell phone providers should have this information available. Additionally, nothing takes the place of an actual field test of the cell phone.
Hearing Aid Compatibility Rating Scales
Hearing Aid Compatible (HAC) compliant device packages are marked with “M” or “T” ratings. The M-rating refers to the microphone mode. The T-rating refers to the telecoil mode.
M-Ratings: Wireless devices rated M3 or M4 meet FCC requirements and are likely to generate less interference to hearing devices than wireless devices that are not labeled. M4 is the better/higher of the two ratings. The higher the M-rating the handset has the lower the Radio Frequency emissions level and higher signal quality the handset will have.
- M3-rating indicates the handset has satisfied the ANSI standard
- M4-rating indicates the handset has exceeded the ANSI standard
T-Ratings: Wireless devices rated T3 or T4 meet FCC requirements and are likely to be more usable with a hearing device's telecoil ("T Switch" or "Telephone Switch") than unrated wireless devices. T4 is the better/higher of the two ratings. The telecoil rating is in reference to telecoils in some hearing aids, the telecoil is a small device that is built into some hearing aids for use with the telephone as well as assistive listening devices. Not all hearing aids have telecoils. To use the telecoil, generally, either the hearing aid is switched to the "T" position or a button on the hearing aid is pushed to select the telecoil setting.
- T3-rating indicates the handset has satisfied the ANSI standard
- T4-rating indicates the handset has exceeded the ANSI standard
When the consumer is attempting to discern the best performance between a hearing aid and cell phone, the numbers from the m-ratings of both the cell phone and hearing aid should be added together (summed up). Of course, if telephone coil compatibility/performance is to be assessed, the t-ratings of each device should be summed. T-ratings should not be summed with m-ratings; the two ratings should always be kept separate.
Possible Ratings for Rated Phones
There are only 6 possible ratings allowed by the FCC for cell phones rated as being hearing aid compatible (HAC). The phone could be rated (from worst to best):
- M4/T3 (or M3/T4)
A good hearing aid user goal would be a hearing aid with an M-3 immunity rating, added to a cell phone with an M-3 emissions rating, summating to a total of 6 would be an excellent hearing aid/cell phone communication ability result. Phones rated M4/T4 have the best chance of being interference-free whether used with your hearing aids in microphone or t-coil mode.
See http://www.hearinglosshelp.com/articles/hacphones.htm for more information on hearing aid compatibility.