Imagine going to the theater but being unable to hear the dialogue clearly and missing the punchlines over and over, despite constantly adjusting the volume on your hearing aid. Imagine trying to fill a prescription and struggling to communicate with the pharmacist about the dosage and timing. Imagine standing on a subway platform and not being able to hear the announcements over the group of rowdy teens a few feet away. This is the daily experience for millions of Americans who have hearing loss, and designers can do something about it.

All images courtesy of Contacta

Designers can improve the everyday experience of people with hearing loss by equipping public, assembly, and commercial spaces with a hearing loop.

It is estimated that one out of seven Americans has some degree of hearing loss. According to the World Health Organization (WHO), an estimated 22.1 percent (57.1 million individuals) in the United States over the age of 12 have experienced hearing loss in at least one ear, and 13.8 percent of the population (35.5 million) have lost hearing in both ears. The number of people with binaural hearing loss (in both ears) is expected to grow to more than 41 million by 2025.

While many people with hearing loss have hearing aids, the technology still struggles to find the signal of interest in a loud room, often drowning the wearer in ambient noise and causing incredible frustration. Designers can improve the experience of people with hearing loss in the built environment by specifying an assistive listening technology that inconspicuously delivers the lecture, presentation, or dialogue directly to the person’s hearing aid, minimizing the ambient noise that can be so distracting. This assistive listening system enables people with hearing aids to clearly hear the featured performance and more easily participate in regular day-to-day activities, such as making a deposit at the bank or purchasing a ticket at a bus station.

This course will take a deeper dive into the different systems available to designers to improve hearing accessibility in both large venues and one-on-one encounters and provide insight into the dramatically different user experience that each solution offers individuals with hearing loss. To better understand the various assistive listening devices available and the strengths and weaknesses of each, it makes sense to start with a quick overview on the mechanics of hearing loss, a few of the terms used to discuss this issue, and an explanation of why hearing aids just aren’t enough.

Defining Sound and Hearing Loss

Sound waves are often described with two metrics: decibels (dB), which measure the intensity of the sound, and hertz (Hz), which refer to the frequency of the sound wave. The human ear can hear a wide range of frequencies broadcast at a number of intensities. More specifically, sounds can be detected by the human ear from the very low 20 Hz to the very high 20,000 Hz. Low-frequency sounds include the beat of a bass drum, the blast from a tuba, and the grumble of thunder, while high-frequency sounds are found in whistles, chirping birds, and the squeals of a child.

As it relates to the level of sound, a person’s hearing threshold describes the level of sound that can be detected by that person’s ear. The hearing threshold of a normal, healthy ear is 0 dB across the full range of 20–20,000 Hz. A soft whisper is often measured at 30 dB, while an ordinary conversation is carried on at around 60 dB and a loud radio produces sound at about 80 dB.

When a person has hearing loss, he or she may have a higher hearing threshold, meaning that sound levels must be louder to be detected by that person’s ear. Mild hearing loss is categorized as a condition where the quietest sounds a person can hear is between 25 and 40 dB. For people with moderate hearing loss, the hearing threshold is even higher, between 40 and 70 dB. People with moderate hearing loss can have difficulty keeping up with conversations if not using some type of hearing aid.

People with hearing aids and cochlear implants often struggle to hear announcements or other important audio signals in areas with a lot of background noise.