Hearing aids and mobile phones haven’t always gotten along as well as they do now. The complex electronics in both devices often caused static, dropped words or squealing interference noises. Thankfully, improvements in technology and new government regulations have made the question “Will this cell phone work together with my hearing aid?” easier to answer. 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. When the hearing aid is in T mode, instead of the microphone it uses its built-in telecoil to directly pick up conversations from inside the phone, in the form of electromagnetic signals. Currently, approximately 60% of hearing aids sold in the US have a telecoil or T mode.
The rating system for these two modes of hearing aid operation uses a scale that ranges from the lowest sensitivity (1) to the highest sensitivity (4). No mobile phone or cordless handset sold in the United States can be sold as hearing aid compatible (HAC) unless it has 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. To determine the compatibility between your hearing aid and a mobile phone you are considering, just add the M and T ratings together; add the M rating of the hearing aid to the M rating of the phone and add the T rating of the hearing aid to the T rating of the phone. A combined rating of 6 or more is considered excellent, a hearing aid/phone combination that would provide highly usable, interference-free performance. A sum of 5 is considered normal and should work fine for typical mobile phone users. A sum of 4 is considered acceptable, but if you are a heavy cell phone user, you may be disappointed or frustrated with this choice.
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.