An investigation into the use of hearing augmentation systems in NSW Trains sheds light on the transport industry.
By Claudia Chiu and Odilia Chan
You always saw this sign on the newer trains while commuting, but have you ever wondered what it meant?
This sign is used to indicate that an audio frequency induction loop (AFIL) system, commonly known as a hearing loop, is installed and in use.
An induction loop system is connected to an amplifier, in which a signal is passed through a loop of wire so as to generate a magnetic field which is transmitted to the telecoil (T-coils), a small coil located inside most hearing aids.
Telecoils are meant to receive magnetic flux signals. According to Gough Lui, who has a Doctorate of Engineering, they were designed originally for use on telephones.
“People who are hearing-impaired would stick the telephone up to their ear, and it would pick up the magnetic flux leakage from the speaker in the telephone and give them a clear sound,” he said.
The ability to hear a birdsong and listen to the audio at a movie cinema, railway station, or even a conference is something most of us take for granted. However, for deaf people, being unable to hear the audio broadcasts in a train station can cause a serious problem.
John Chapman, who is deaf, recalled an incident where he and his wife had to change trains on the way. While his wife heard the announcement, he had no idea until she informed him. A staff member who knew about his condition instead took the initiative to check if he was aware of the changes.
“If I hadn’t told him and was travelling on my own, it would have been extremely confusing,” he said.
Peter Kerley, a Board member of Better Hearing Australia (Sydney) who is hard of hearing, further notes the importance of being able to hear during such situations.
“If there is an emergency, everything matters,” he said. “If, for example, they decide to switch for maintenance reasons and have buses instead of trains, then access to information is very important.”
When deaf people put their hearing aids on, a few issues arise. The background noise and the listener’s physical distance from the source may disturb the audio broadcast and transmit the signal to them unclearly.
Since the hearing loop system is operating with a magnetic field, metal objects in the environment might influence the frequency level in an audio transmission, and that electromagnetic interference (EMI) can create a buzz or hum sound in the listener’s T-coil.
If the environmental noise is too loud, it may be impossible for deaf people to receive a clear announcement on the train changing platform until the offending noise source has been removed. Where privacy is important, the loop needs to be carefully installed.
“The interfering magnetic field can be negated by moving your head a little bit or sitting in a slightly different location further away from the source interference,” Gough said.
“If you can move away from the source of the interference to some degree and reduce it so you can improve what we call the signal to noise ratio and thus improve intelligibility and the ability to comprehend the sound.”
“Some people may find it necessary to sit closer to the front or the back of the carriage or in the upper deck for receiving a louder and stronger signal.”
Waratah (A-set) trains have hearing loops in all areas. Oscar and Millennium trains also have induction loops installed, but only in the upper levels.
Reception decks that allow hearing aid wearers to hear the receptionist’s conversation with ease, even when behind a glass security partition.
The direct copy of the conversation between a receptionist and customer is induced by the T-coil. The hearing aid converts this signal into an audible sound for the deaf people to hear.
Interestingly, the installation of a reception desk induction loop system is no longer useful for deaf people because no tickets can be sold at the Sydney railway station’s counter.
Now, we only can travel with a recently introduced Opal card and top up with the machines on the platforms. Most importantly, there’s no face-to-face communication available at the counter to assist those deaf people.
While most of the newer trains with induction loops, the same cannot be said with train stations. Only 12 out of 311 train stations have audio frequency induction loop systems installed. According to Kepley, it is highly likely these induction loops are switched off.
