One of the first things people with hearing loss observe is “I hear people fine, but I don’t understand what they are saying.”
This is a consistent complaint of individuals who are experiencing the effects of a “sloping high frequency hearing loss.“
What’s happening and why do so many have this complaint?
Hearing loss involves not only our ears, but also our brain: where sound waves are coded by the ears and then translated into meaningful words. While hearing loss can present itself in varying degrees of severity in different frequencies, a very common progression of inner ear hearing loss is sloping high frequency hearing loss.
We commonly measure hearing from 250 to 8000 Hz. Individuals with “high frequency” hearing loss have no loss at frequencies below 1000 Hz (lower pitched frequencies), but have abnormal results in the range of 1000 to 8000 Hz (higher pitched frequencies). High frequency hearing loss is one of the most common variances of hearing loss there is.
Different speech signals produce different frequencies
When examining human speech signals, we see that there are lower pitched sounds or vowels (A, E, I, O and U) and higher pitched sounds or consonants (S,F , Th, Sh, Ch, K, P and H). Being able to hear vowels in the lower pitched frequencies gives us a sensation of hearing speech, but not being able to hear higher pitched sound or “consonants” is what compromises our ability to understand full words. (So we hear, but we don’t understand.)
The high-pitched frequencies where consonants occur is where the discrimination of different words happen. When we have high-frequency hearing loss, we lose the ability to hear the “consonant” sounds efficiently and, thus, our ability to tell the difference between words such as ‘Cat” or “Hat”.
Key sounds and letters aren’t heard clearly
Imagine having a book with every S, F, Th, Sh, Ch, K, P and H erased. You could read part of the book and understand some of it, but you would not be able to understand many key words and phrases and, as a result, be challenged to understand it. This is what is happening with a high frequency hearing loss. You can hear part of the message, however your high frequency loss has “erased” the key sounds or letters needed for discrimination and understanding.
Luckily, high frequency hearing loss can usually be helped with proper diagnosis and appropriate amplification.