Customer Support
viii Dolphin CT50 Mobile Computer with Windows 10 IoT Mobile Enterprise User Guide
Hearing Aid Compatibility (HAC)
Device Listings
The standard for compatibility of digital wireless devices with hearing 
aids is set forth in American National Standards Institute (ANSI) 
standard C63.19. ANSI C63.19 contains these two sets of standards:
• An “M” rating from M1 to M4 for reduced radio frequency (RF) 
interference to enable acoustic coupling with hearing aids that do not 
operate in t-coil mode.
• A “T” rating from T1 to T4 to enable inductive coupling with hearing 
aids operating in t-coil mode.
A digital wireless handset is considered hearing aid compatible for 
acoustic coupling if it meets at least an “M3” rating under the ANSI 
standard. A digital wireless handset is considered hearing aid 
compatible for inductive coupling if it meets at least a “T3” rating under 
the ANSI standard
.
M-Ratings: Devices rated M3 or M4 meet FCC requirements and are 
likely to generate less interference with hearing devices than devices 
that are not labeled. M4 is the superior/higher of the two ratings.
T-Ratings: Devices rated T3 or T4 meet FCC requirements and are likely 
to be more usable with a hearing device’s t-coil than unrated devices. T4 
is the superior/higher of the two ratings.
These ratings are not guaranteed. Results will vary depending on the 
level of immunity of your hearing device and the degree of your hearing 
loss. If your hearing device happens to be vulnerable to interference, you 
may not be able to use a rated device successfully. Trying out the device 
with your hearing device is the best way to evaluate it for your personal 
needs.
When some wireless devices are used near some hearing devices such 
as hearing aids and implants, users may detect a buzzing or humming 
noise. Some hearing devices are more immune than others to this 
interference noise. Wireless devices may also vary in the amount of 
interference they generate. The more immune the hearing aid device is, 
the less likely one is to experience interference noise from the wireless 
device.
Hearing aid devices may also be rated. Adding the ratings of the hearing 
aid and the device can predict the usability of the two devices together:
• Any combined rating equal to or greater than six offers the best use.
• Any combined rating equal to five is considered normal use.