The Nature of Hearing Loss and the Fundamentals of Proper Amplification (Part I)

Take a poll of audiologists about the observation or complaint they most often receive from patients and I’m willing to wager that the hands-down, clear-and-away, favorite would be something to the effect of “I hear just fine, but speech isn’t clear.”  Variations would include “Everyone mumbles” and “I just can’t make out the words”.

There’s a reason for all of this perceived mumbling, and that is the nature of sensorineural hearing loss, the most common form of hearing loss and often referred to as nerve deafness.  Sensorineural hearing loss occurs in the inner ear, the cochlea, and is typically non-reversible by medicine or surgery.  The causes are varied, but the leading ones are presbycusis (age-related), ototoxicity (drug interactions), or excessive noise exposure.

However, no matter what the cause of sensorineural hearing loss, the effect is often the same – the vowels of speech remain audible [a, e, i, o, u], while the consonants of speech [s, f, t, b, etc.] become inaudible.

To use a real life example of how this can affect one’s daily conversations, imagine printed text without many of the consonants.  For instance, try and decipher the following question:

"Wi__ __e __illie_ wi_ __e Wor__ _erie_ __i_ _ea_?"

Before I reveal the true identity of that sentence, let me demonstrate what context can do to help someone with hearing loss “fill in the blanks” on an auditory perception level.  Let’s say I showed you these two images before giving you the sentence:

      

 

Now, with context added, you can see how someone with a classic case of sensorineural hearing loss, while certainly impaired, can still manage to get by in daily life.  Having some background or context to go along with the sounds of speech that are actually being perceived make communication possible.  More difficult, but still possible.

By the way, in case you haven’t guessed yet, the phrase is “Will the Phillies win the World Series this year?”

Next, in Part II, we’ll discuss why certain sounds of speech become audible and inaudible to those with the most common forms of sensorineural hearing loss.

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The preceding was part of A four part series at Auris Repletus entitled, "The Nature of Hearing Loss and the Fundamentals of Proper Amplification"

- Part I
- Part II
- Part III
- Part IV