Hearing aid compatibility (often abbreviated HAC) is a standard that measures how well a phone works with hearing aids and cochlear implants. It exists because wireless phones can create electromagnetic interference that produces buzzing, static, or other unwanted noise for hearing aid users. The FCC requires mobile phone manufacturers and wireless carriers to offer handsets that meet specific compatibility thresholds, rated on a simple scale you can check before buying.
How the Rating System Works
Hearing aid compatible phones receive two separate ratings: an M-rating and a T-rating, each on a scale from 1 to 4. The M-rating measures how well the phone performs when your hearing aid is in its normal microphone mode, picking up sound acoustically the way it usually does. A higher M-rating means less interference, buzzing, and static during calls. M4 is the best possible score.
The T-rating measures performance with hearing aids that have a telecoil, a small coil of wire inside the device that picks up electromagnetic signals directly from the phone instead of relying on the microphone. T4 is the best score here as well. The FCC considers a phone hearing aid compatible if it scores at least M3 for acoustic coupling and at least T3 for telecoil coupling.
Not every hearing aid has a telecoil, so the M-rating matters for all hearing aid users while the T-rating only applies if your device includes one. If you’re unsure whether yours does, your audiologist or the manufacturer’s spec sheet will confirm it.
Telecoil vs. Microphone Coupling
When you hold a phone up to a hearing aid set in microphone mode, two problems tend to arise. First, the hearing aid amplifies everything nearby, not just the caller’s voice, so background noise competes with the conversation. Second, the phone’s proximity to the hearing aid microphone can trigger feedback, that high-pitched squeal caused by sound looping between the speaker and microphone.
A telecoil sidesteps both issues. Because it picks up electromagnetic signals rather than acoustic sound, it ignores ambient noise entirely and delivers only the phone’s audio. It also eliminates feedback since there’s no microphone involved in the process. The tradeoff is that some users find telecoil output quieter than expected, particularly at lower frequencies within the typical phone bandwidth of 300 to 3,300 Hz. If phone calls sound too soft on the telecoil setting, your audiologist can often adjust the telecoil’s programming to better match your microphone levels.
What You’ll See on Phone Packaging
FCC rules require specific hearing aid compatibility information on a phone’s external packaging. The label must state that the handset is hearing aid compatible, specify whether it meets telecoil or Bluetooth coupling requirements (or both), and list the phone’s actual conversational gain with and without hearing aids. Inside the box, either a printed insert or user manual must explain how to turn coupling features on and off and note whether any frequency bands haven’t been certified as compatible.
Some manufacturers now use digital labeling instead of printed inserts. In that case, the box will include a QR code and a website address where you can find the detailed compatibility information online. The external printed label with the basic compatibility statement is still required either way.
The Shift to 100% Compatibility
For years, manufacturers only had to offer a certain number of compatible models rather than making every phone meet the standard. That’s changing. In October 2024, the FCC adopted a rule requiring all future wireless handset models sold in the United States to be hearing aid compatible. The rollout follows a staggered timeline: handset manufacturers must comply by December 14, 2026, nationwide service providers by June 14, 2027, and smaller non-nationwide providers by June 12, 2028. Once fully phased in, every new phone on the market will meet at least the minimum M3 and T3 thresholds.
The current technical benchmark is the 2019 ANSI standard, which replaced the older 2011 version. Phones that meet it are simply labeled “hearing aid compatible” rather than requiring consumers to decode multiple rating numbers, though the specific M and T scores still appear for those who want them. The 2019 standard also introduced a volume control requirement ensuring phones produce adequate sound levels for people with hearing loss, whether or not they use hearing aids.
Bluetooth and Direct Streaming
The M and T rating system was designed for traditional phone calls held up to the ear. Most modern hearing aids now also support direct Bluetooth streaming, which bypasses the acoustic and electromagnetic coupling issue entirely by sending audio wirelessly straight to the hearing aid.
Currently, most hearing aids use proprietary Bluetooth Low Energy protocols that work with iPhones, Android phones, or both, depending on the manufacturer. The next generation, called LE Audio, is a universal standard that will work across all brands without proprietary workarounds. It comes in two forms. Unicast mode streams directly from a personal device like a phone or tablet to your hearing aids with high audio quality and low delay. Broadcast mode, branded as Auracast, lets public venues like airports, houses of worship, and stadiums stream audio that any compatible hearing aid can tune into, similar to how a telecoil works with a hearing loop but without requiring any installed hardware.
LE Audio supports multiple simultaneous listeners, offers better sound quality than many telecoil setups, and can even provide language selection in multilingual environments. It doesn’t replace the M and T rating system for traditional calls, but for streaming audio it represents a significant step forward in accessibility.
How to Check Compatibility
If you’re shopping for a new phone, look for the HAC label on the box or check the manufacturer’s specifications online. An M3/T3 rating is the minimum the FCC considers compatible, but M4/T4 will give you the least interference. If your hearing aid has Bluetooth streaming capability, also check whether the phone supports the same Bluetooth protocol your hearing aids use, since not all pairings work seamlessly yet.
For the hearing aid side, compatibility ratings exist too. Hearing aids receive their own immunity ratings on the same 1 to 4 scale. Combining a high-rated phone with a high-rated hearing aid produces the best results. Adding the phone’s M-rating to the hearing aid’s M-rating gives a combined score: a total of 5 or above generally means excellent performance, while a combined score of 6 or higher is considered the best achievable pairing for acoustic coupling. The same math applies to T-ratings for telecoil use.