In the past, the complex electronics of mobile phones often interacted badly with the electronics of hearing aids, resulting in interference between the two devices that was perceived as static, screeching or whistling noises, or missing words. Compatibility issues are now largely a thing of the past thanks to cell phone technology advances, hearing aid technology advances and government regulations.Government regulations introduces mandatory labeling requirements making it much easier to find a mobile phone compatible with your existing 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).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 instead uses an inductive process to pick up electromagnetic signals inside the phone directly, without the need for a microphone. T mode is standard in roughly 60 percent of all hearing aids.
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).To be labeled or marketed as a hearing aid-compatible phone in the US, a cordless handset or mobile phone must have a minimum rating of T3 or M3.
A similar scale has been applied to hearing aids. This scale rates the resistance to interference from other devices emitting radio waves and rates the overall sensitivity in M or T mode.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 combined rating of 6 or more is considered excellent, a hearing aid/phone combination that would provide highly usable, interference-free performance. A total rating of 5 is considered normal and satisfactory to people with normal usage patterns.A combined rating of 4 is considered usable for brief calls, but may not be suitable for extended phone use.
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.