Up until recently, the complex electronics of cell phones often interacted poorly with the electronics of hearing aids, resulting in interference between the two devices that was perceived as static, screeching or whistling noises, or lost words. Thankfully, advances in technology and new government regulations have made the issue “Will this cell phone work with my hearing aid?” simpler to answer. The labeling requirements mandated by the new government regulations make it easy to find a mobile phone that is compatible with your hearing aid.

Understanding the rating system requires a bit of knowledge about the modes that hearing aids can operate in. There is an M mode (which stands for microphone) and a T mode (which stands for telecoil). When your hearing aid is in M mode, it uses the built-in microphone to pick up audible sounds from around you and amplify them to make them easier for you to hear. 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 sold in the United States as hearing aid compatible (HAC), a mobile phone or cordless handset must have a rating of at least 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 mobile 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.

If you are shopping for a mobile phone online, you can usually use this combined rating to determine how compatible the phone you are interested in buying 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.