Page 321 - Mechatronics for Safety, Security and Dependability in a New Era

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WIRELESS COMMUNICATION WITH
BLUETOOTH HEARING PROTECTOR

Mika Oinonen, Pasi Myllymaki, Matti Ritamaki, Markku Kivikoski

Tampere University of Technology, Institute of Electronics, P.O. Box
692, FIN-33101, Tampere, Finland

ABSTRACT

In today's mobile world, it is important to be easily accessible via a cellular phone. It is also important
to protect the hearing in noisy environments. Often these two requirements must be fulfilled
simultaneously. As a solution, a prototype of a Bluetooth hearing protector was constructed. A
microstrip antenna was designed using a trial-and-error method. The device was installed inside a
high-quality passive hearing protector and a boom microphone was attached to the earcup. The
developed Bluetooth hearing protector enables both wireless communication and hearing protection,
while also eliminating the need for inconvenient cables, thereby improving safety and accessibility.

KEYWORDS

Wireless communication, Bluetooth, hearing protection, safety, wearable, inverted-F antenna

INTRODUCTION
Hearing protection is vital in noisy environments. Strong impulse noise, especially, is hazardous and
can cause permanent hearing loss. Traditional passive hearing protectors attenuate noise efficiently and
protect the inner ear from loud noise. However, when wearing a passive hearing protector, it is almost
impossible to use a cellular phone, and important calls may be missed if the ringing tone is not heard.
It is possible to connect a cellular phone into an electronic hearing protector with a cable. While this
provides communication and hearing protection at the same time, the cable can be inconvenient in
many work tasks. A Bluetooth radio link between the cellular phone and the hearing protector makes it
possible to communicate with others and work in noisy environments without inconvenient cables. The
cellular phone can be kept in the pocket and incoming calls can be answered simply by pressing a
button on the earcup when the ringing tone is heard inside the earcups.

During the last few years, the wireless Bluetooth radio link has been replacing cables, e.g. in computer
products. Bluetooth connection can also be used to replace the cable between the cellular phone and
the hearing protector, provided that the cellular phone supports a Bluetooth connection. Bluetooth is a
short-range radio link, which operates in the globally available licence-free 2.4 GHz ISM band. The
audio data rate is 64 kb/s, as in the GSM system (Bray 2001). Risk of interference with other devices is