Hearing aids have not previously always worked effectively with cellular phones, because of electronic interference between the two devices that caused static, whizzing or squealing noises, or lost words. Technology improvements along with new regulations have mostly eliminated this problem. Today cell phone – hearing aid compatibility isn’t the huge problem it used to be. The regulations mandated new labeling requirements and ratings that help you to find a mobile phone that works well with your hearing aid.
To understand how this rating system works, you should first understand the two modes that hearing aids work in – M mode (for microphone) and T mode (for telecoil). In M mode, the hearing aid uses the internal microphone to detect sounds and amplify them. In T mode, the hearing aid uses telecoil technology instead. The hearing aid is able to pick up the electromagnetic signals from inside the phone directly. Roughly 60 percent of all mobile phones sold in the U.S. have a telecoil (T) mode.
The two modes – M and T – are each rated on a scale of 1 to 4 where 1 is the lowest sensitivity and 4 is the highest. To be labeled as hearing aid compatible (HAC) a mobile phone must carry a minimum rating of M3 or T3.
Hearing aids themselves also carry M and T ratings to indicate their sensitivity and ability to block interference in each mode. When shopping for a phone, to determine its compatibility with your hearing aid, simply add its M and T ratings together with those of the phone to create a combined rating. A sum of 6 or more makes a solid pairing. That hearing aid and cell phone combination should work well for you. A combined rating of 5 is thought of as normal, and suitable for most people. If the combined rating is 4, this is thought of as acceptable but not very usable if you make a lot of extended phone calls.
This combined rating system makes it easy to shop for a mobile phone online, because it easily allows you to determine how compatible it will be with your hearing aid. If you are able to shop in a store that allows you to “try before you buy” and actually use the phone you want while wearing your hearing aid, that is of course a better idea.