Hearing aids and mobile phones haven’t always gotten along as well as they do today. The intricate electronics in both devices often triggered static, lost words or screeching interference noises. Technology improvements along with new regulations have mostly eliminated this issue. Today cell phone – hearing aid compatibility isn’t the huge challenge it used to be. To help consumers shop for the right hearing aid compatible cell phone, the new regulations include a standard rating system and labeling requirement.

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, your hearing aid uses its built-in microphone to pick up audible sounds from the environment and amplify them so that you can hear 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. The T mode is important when shopping for a phone, because at least 60% of hearing aids sold in the United States have one.

Under the new regulations, these two modes of operation have ratings that range from 1 (the lowest sensitivity) to 4 (the highest sensitivity). To be labeled as hearing aid compatible (HAC) a cell phone must carry a minimum rating of M3 or T3.

Hearing aids and cochlear implants have a similar M and T rating system to certify how sensitive they are in each mode, and how resistant they are to radio frequency interference. If you know the M and T ratings for your hearing aid, to determine its compatibility with any mobile phone, just add the two sets of ratings together. A sum of 6 or more makes a solid pairing. That hearing aid and cell phone combination should work well for you. A sum of 5 is considered normal and should work fine for typical cell phone users. A combined rating of 4 is considered usable for brief calls, but may not be suitable for extended phone use.

Since being introduced, the new rating system has made it much easier to shop for a cell phone online and determine its compatibility with your hearing aid in advance. A better approach, of course, would be to go to a store that allows you to “try before you buy,” and actually use the phone you want while wearing your hearing aid, in both M and T modes.