What is hearing aid compatible, or HAC? Hearing aid compatible (HAC) phones are designed to work well with hearing aids, keeping people with hearing loss more connected. This section provides information on hearing aid compatibility in general.
The Microphone Standard (The "M" Rating)
The Federal Communications Commission (FCC) requires that wireless carriers—those companies that provide the wireless "coverage" for phones (T-Mobile, Verizon Wireless, etc.) offer different types of phones that are hearing aid compatible.
Phones with a microphone ("M") rating of M3 or M4 meet or exceed the FCC's standards: the higher the M-rating, the lower the radio frequency emissions level, and the higher the signal quality the phone will have.
The Telecoil Standard (The "T" Rating)
As with the Microphone Standard, the FCC also requires wireless carriers to offer different types of phones that work with telecoils. Phones with a telecoil ("T") rating of T3 or T4 meet or exceed the FCC's telecoil standards, and should work well with telecoil-equipped cellphones.
More About Telecoils (T-Coils)
A telecoil (often called a "t-coil") is a small device that is built into some hearing aids. This device provides a quick, direct connection to telephones and to some assistive listening devices. The telecoil does this by picking up magnetic fields generated by the phone and converting these fields into sound.
Telecoils are particularly useful for telephone communication because they allow a person's hearing aid to amplify the phone's sound without creating feedback or "whistling." This is because the sound is passed between the hearing aid and the phone directly through this magnetic field, instead of acoustically through the air, so background noise is often reduced or eliminated, especially when using a cellphone in noisy situations.
Cellphones with a "T" rating can be used with a hearing aid's telecoil, often providing a better user experience. While not all hearing aids have telecoils, those that do usually need to be switched to "telecoil mode" by the user.
More About Cellphone Interference
Interference between cellphones and hearing aids is what causes the buzzing, whistling, and/or static users hear. This interference is typically caused by both magnetic and radio pulses given off by the phone. This interference is reduced in hearing aid compatible phones, and for hearing aids to be immune to such fields. This immunity can come from "shielding" inside the hearing aid, or from circuitry specifically designed to reduce interference. Combined with technology in the hearing aid that give it a high M and T rating, these hearing aid innovations make the safety, freedom and convenience of a wireless phone a reality for many hearing aid users.