HAC Wireless Handsets

Hearing Aid Compatibility (HAC) rating system

Cell Phones and Hearing Aids

Hearing aid wearers may experience audible interference when using a digital wireless telephone due to radio frequency (RF) emissions from the phone, regardless of whether acoustic (microphone) or inductive (telecoil) coupling is used. RF interference does not occur for all combinations of digital wireless telephones and hearing aids. However, when interference does occur, the buzzing sound can make understanding speech difficult, communication over cell phones annoying and, in the most severe cases, render the phone completely unusable to the hearing aid wearer. When a wireless phone is in communication with its network, an electromagnetic field is present around the phone's antenna. During communication over a digital wireless phone this field pulses. It is this pulsing energy that may be picked up by the hearing aid's microphone or telecoil circuitry and heard as a buzzing sound (i.e., interference) through the wearer's hearing aid. Telecoil users may also experience electromagnetic (EM) interference which originates from the cell phone's electronic elements such as its back-lighting, display, keypad, battery and circuit board.

ANSI C 63.19 Standard

Motorola K1m KRAZR

Since both the cellphone and the hearing aid contribute to the delivered sound quality, US standard ANSI C63.19-2001 was developed to ensure hearing aid compatibility (HAC). ANSI C63.19 is a standard that was developed by engineers and audiologists to measure both the wireless handset RF interference signal strength and the hearing instrument RF interference immunity. Included in the development was a consumer oriented categorical rating system to facilitate their determination of the sound quality to be expected by a user with a particular combination of a C63.19 rated hearing aid and a C63.19 rated wireless device such as a cellular telephone. Not all handsets will be C63.19 rated, but since Sept. 16, 2005 the C63.19 rating for handsets will be readily visible to prospective purchasers in the US on the exterior of the package of HAC compliant handsets. 

The C63.19 category rating system assigns a device a numerical value from 1 to 4. The sound system rating is the sum of the handset and the hearing aid rating category value. The greater the sum the better is the expected sound quality. Further there are 2 ratings, M for signals coupled to the microphone and T for telecoil coupling. M ratings for handsets were available by Sept. 16, 2005 while T ratings will be added no later than a year later. The following table was developed for the C63.19 standard to provide hearing instrument users insight on whether a particular wireless device will not interfere with a particular hearing aid.  For example a sum of 4 would indicate that the combination of wireless device and hearing aid is usable; a sum of 5 would indicate that the WD and hearing aid would provide normal use; and a sum of 6 or greater would indicate that the wireless device and hearing aid would provide excellent performance. Remember, however, that the number on your cellular phone (either M_ or T_) is half of the equation. That handset number needs to be added to the hearing device number to apply the following chart.

Figure 1

Acoustic Coupling to a Hearing Aid's Microphone

CC Communications offers many handsets that are compatible with hearing aids. Cell phones offered by the company have been tested for reduced RF emissions according to the ANSI C63.19 standard. Those that are considered passing (those with a rating of "good" or "excellent") for use with hearing aids set in microphone mode will be assigned a HAC rating of M3 or M4. The "M" stands for microphone so that the consumer will know the phone has been tested and rated for acoustic coupling purposes. The higher the "M" rating, the less likely the hearing aid user will experience interference when the hearing aid is set in the microphone mode while using the cell phone.

Inductive Coupling to a Hearing Aid's Microphone

As with acoustic coupling, cell phones will be tested for their telecoil coupling capability according to the ANSI C63.19 standard. Those that are considered passing (those with a rating of "good" or "excellent") for use with hearing aids set in telecoil mode will be assigned a HCA ratingof T3 or T4. The "T" stands for telecoil so that consumer will know the phone has been tested and rated for inductive coupling purposes. The higher the "T" rating, the less likely the hearing aid user will experience interference when the hearing aid is set in the telecoil mode while usingthe cell phone.

Purchasing a Cell Phone for use with Hearing Aids
Only those phones that meet a minimum rating of M3 or M4 will be labeled for HAC compliance for acoustic coupling. Only those phones that meet a minimum rating of T3 or T4 will be labeled for inductive coupling. Labels showing HAC compliant ratings will appear on the product's packaging, on the display card by the phone in service provider operated retail stores and in the product's manual or packaging insert. Because these ratings do not guarantee performance, it is strongly recommended that individuals who use hearing aids take the opportunity to "try before you buy" any wireless device and to closely examine the return policy for the device and the service provider's policy on early termination of contracts before signing up for service.

Tips for selecting a handset

• If the hearing aid will be coupled acoustically, look for cell phones rated M3 or M4 .
• If the hearing aid will be coupled inductively (telecoil), look for cell phone rated T3 or T4.
• These M or T ratings should be used as a general guide to narrow the search for a cell phone to try out before making a purchase.
• Be sure the cell phone has an easy-to-use volume control.
• It is the customer's responsibility to make sure any cell phone that doesn't work with his/her particular hearing aid is returned before any early termination fees go into effect.

CC Communications currently offers the following models¹:

The level of functionality is determined by reference to figure 1 above.