For a hearing impaired person, it can be difficult to hear an ordinary smoke alarm, and that is why smoke alarms especially for people with hearing loss have been developed.
There are a number of different solutions, for example, alarms which send out a strong light and activate a small vibrator, which the hearing impaired person can place under their pillow, or alarms which send out low-frequency sounds. Low-frequency alarms send out a sound with a frequency of 520 Hz, whereas a normal alarm sends out a sound with a frequency of around 3000-4000 Hz.
How effective are the alarms?
A study published in 2009 in the journal Ear and Hearing showed, that some smoke alarms are more effective than others when it comes to waking people with hearing loss.
According to the study, the alarms which send out a strong light are not particularly effective. The small vibrator under the pillow is however effective with regards to people with severe or total hearing loss, but with regards to people with mild or moderate hearing loss, the alarms with low-frequency sounds are the most effective. According to the study, the likelihood of a hearing impaired person being woken by a low-frequency alarm is seven times greater than by a normal smoke alarm.
A new type of alarm
In Japan, a group of researchers from the Department of Medicine at Shiga University have developed a smoke alarm which works through smell. When the alarm is triggered, it sends out a very strong and sharp smell, which comes from the wasabi radish.
Different smells were tested in connection with the development of the alarm, but wasabi proved to be the most effective in waking people. The alarm was tested on 14 sleeping people, of which one was deaf. The 13 people with normal hearing woke in the space of two minutes after the wasabi extract was squirted into the room, while the deaf person woke after just 10 seconds.
Source: www.hearinglossweb.com & www.dbi-net.dk