What is Hearing Impairment?
There are different conditions that can affect a person's hearing, including but not limited to:
- Partial hearing loss
- Severe hearing loss
- Complete hearing loss
While the number of people with complete hearing loss (full deafness) is relatively low, there are many people with severe loss, and more than half of the population is believed to have at least partial hearing loss. Partial loss often comes on as people get older, and more and more cases are occurring in younger people due to the increasing amount of noise in urban environments, along with misuse of portable audio devices.
Most of these impairments are "invisible", meaning that one cannot look at a person and tell if she or he has one of these impairments, especially with the availability of in-ear hearing aids. Therefore, it is important to recognize that far more people than you think could suffer from some form of hearing impairment, even the higher level impairments.
How Does Someone with Hearing Impairment Experience the Web?
Partial Hearing Loss
Even with only 15 to 20 percent hearing loss, it can be very difficult to understand voices, especially when multiple people are talking over each other or there is other background noise present while someone is speaking.
Partial loss (as well as severe loss) is often accompanied by tinnitus, which is hearing sounds (usually a ringing sound) when no sound is present. This further impedes the ability to process real sounds, as the brain has to work harder to filter out the extra noise.
Severe Hearing Loss
At these higher levels of loss, understanding voices can be impossible without hearing aids, and even with hearing aids will be much more difficult than it is for someone with normal hearing. People with severe loss typically prefer reading information over hearing it and make heavy use of captions on television programs, movies, online videos and other digital content that has an audio component.
Complete Hearing Loss
While somewhat rare, there are people with complete hearing loss, often a condition occurring from birth, though some diseases can result in complete or near-complete loss. Someone with this level of impairment will be unable to use the audio component of any digital media and will be reliant on captions (for multimedia presentations) or transcripts (for audio-only presentations).
Web Accessibility for Hearing Impairment
There are several best practices for making website content as accessible as possible for people with audio impairment:
- Multimedia (audio plus video, e.g. "videos") must have accurate captions for the audio component. Accuracy is the most important part: systems like YouTube and MediaSpace will automatically caption uploaded content, but those captions must be reviewed and corrected. Artificial intelligence is still not good enough to reliably transcribe human voices without some manual intervention.
- Audio-only presentations (e.g. "podcasts") must have accurate transcripts. Note that transcripts are only acceptable when the presentation is audio-only. If there is audio synchronized in any way with video, then the presentation must be captioned so that the transcribed text will be available in sync with the video component.
- Helpful tip: planning ahead and working from an outline when creating a recorded presentation makes it much easier to go back and add the captions.
- Important: These guidelines apply not just to recorded presentations, but to live streamed events as well. In this case, you would need to provide live captioning, which would require a trained captionist.