If you have ever had a hearing test, you know that what you hear is a series of beeps at different frequencies, otherwise known as pitch. When you have a hearing test, the softest sound that you hear at each frequency is recorded on a graph called an Audiogram. This part of the test determines what you can and cannot hear. In addition, you may also be asked to repeat words in quiet and repeat words/sentences in background noise. This part of the test helps the examiner to document how you are processing speech sounds. Unfortunately, hearing does not always mean understanding speech, which can be frustrating. Hopefully, in the next few paragraphs, I can help to explain the correlation between hearing and understanding.
When we are born, we hear frequencies that range from 20-20,000 Hertz. Hertz is cycles per second, and the perception of frequency is pitch. For example, lower-pitched sounds are more bass, and high-frequency sounds have more treble. A very soft high-frequency sound would be birds chirping, and a soft low-frequency sound would be water dripping in a faucet. Examples of very loud low-frequency sounds would be a lawn mower, and a loud high-frequency sound would be a motorcycle speeding past. As we age, we start to lose the ability to hear high-pitched or high-frequency sounds. This is called presbycusis or age-related hearing loss. This occurs naturally due to our anatomy and is made worse by noise exposure, medications, and other diseases.
For many people, as we get into our 50s and 60s, the ability to hear higher-frequency sounds starts to affect the range of hearing certain speech sounds. Vowel sounds (a/e/i/o/u) tend to be lower frequency and louder, whereas consonant sounds tend to be higher frequency and softer. The consonant sounds in the English language are usually what make speech clear. For example, the difference between the word ‘bud’ and ‘bus’ is the very soft, high-frequency ‘s’ sound. You can experiment yourself by making an A sound loud, as in the word apple, and you’ll notice that it is easy. In contrast, making the S sound louder, as in the word soft, is difficult. We already discussed that as we age, we stop hearing high-frequency sounds but still hear lower-frequency sounds. The important speech sounds that help us understand speech are soft high-frequency sounds. If you have a high-frequency hearing loss, then you are not ‘hearing’ the high-frequency consonant sounds that are important to help you ‘understand’ speech. Most people will gradually compensate for the missing high frequencies; however, the more background noises, distractions, and the worse the hearing gets, make it more difficult to understand speech. If you are experiencing this, your family and friends might notice before you and comment to you about not hearing well. This is definitely an indication that it is time to get your hearing tested!