Sensorineural Hearing Loss
The most common form of hearing loss is sensorineural hearing loss, often labelled "nerve deafness" (see below), affecting tens of millions of people. The most common complaint is being able to hear speech, but not understand what is being said. Usually, in cases of sensorineural hearing loss, patients lose more of their high frequency hearing then their low frequency hearing. Since the vowels of speech (a, e, i, o, u) are low frequency in nature, they are almost always audible, while the consonants of speech (s, f, t, p, etc.) are high frequency sounds, and are therefore often inaudible. This results in speech that sounds mumbled or garbled to the listener.
To illustrate further, below are the results of a hypothetical hearing test. The red line is the right ear and the blue line is the left ear. Any sound located below the lines is theoretically audible to the patient and any sound above the lines isinaudible. As you can see, while some sounds of speech are audible -- "I can hear people" -- certain others are not -- "it seems as if everyone mumbles".
* "Nerve deafness" is a somewhat misleading term because typical nerve deafness is not a pathology of nerve, but is usually due to a loss of sensory cells in the inner ear, or cochlea.