Hearing Loss

( Written By: Manfred Stoifl ) Hearing Loss

·         Signs of hearing loss 

·         Hearing loss in one ear 

·         Profound hearing loss 

Hearing Loss 

Hearing loss is categorized depending on the severity, frequency characteristics, location of the problem in the auditory system and if one or both ears are affected. More recently more attention has been  paid to the resulting perceptual problem, the individuals perceived handicap and associated health problems.

Depending on the degree and the kind of hearing loss the associated handicap will differ vastly

For many people first signs of hearing loss are not that that they have great difficulty hearing sounds Their problems are more perceptual, which means that they can actually hear quite well but have difficulty to understand language clearly.This holds especially true in challenging listening environments with noise of competing signals present. 

Cause of this is that in most cases mild hearing loss affects the high frequencies, which carry most of the speech information, more than the low frequencies which are more important for loudness perception. Someone with a mild or even moderate hearing loss might hear the low frequency quite well, which would give them a good perception of loudness but due to a loss in the high frequency having significant problems understanding speech.

Classification of hearing loss is based on severity ranges from mild, a hearing loss of 20 – 40dB, moderate, a hearing loss of 40 – 65 dB, and severe, a hearing loss of 65-90 dB, to finally a profound

hearing loss with a loss greater than 90 dB.

Often a hearing loss is not the same over all frequencies, which makes a classification purely on severity not very meaningful.

Additional terminology is used to describe the shape of an audiogram line over all tested frequencies. Flat means a minimal variation over all test frequencies Mildly to steep sloping indicates that hearing in the low frequencies is significantly better than hearing in the higher frequency ranges.

Ski-slope means, that hearing in the lower, often up to 1-2 KHz range is normal or near normal and subsequently drops steeply towards the high frequencies.

A Cookie- bite means that the low and high frequencies are relatively good with the mid frequencies being much worse, creating a valley in the middle of the audiogram which looks like someone took a bite out of a big cookie.

Reverse slope indicates that the lower frequencies are worse than the high frequencies.

Finally, we have the left corner audiogram which means, that the patient can only hear some low frequencies at high intensity levels.

Hearing loss can be caused by problems in different locations over the human auditory system.

Conductive hearing loss indicates that the problem lies within the conductive part of the ear, which consists of the outer and middle ear. 

Sensory-Neural hearing loss means the problem lies in the cochlear, the retro-cochlear nerve structure or the auditory centres in the brain.

If the problem has a combined source in the conductive area as well as beyond it's called a mixed hearing loss.

A Sensory-Neural hearing loss may be further defined as a Sensory Hearing loss if the problem can be isolated to the cochlear, whereaswith retro cochlear hearing loss,  the problems are within the physical nerve structures and the brain stem.With Central Auditory Processing disorder,the hearing problem is not related to a physical cause, but the inability of the central auditory system to accurately, quickly and automatically work with auditory information received from the cochlear.

In the great majority both ears are similarly affected by a hearing problem, but in cases where there is hearing loss in one ear only we talk of only single sided hearing loss. All characteristics above may apply in equal fashion also if only one ear has a loss.

The above categorizes hearing loss by degree and location. Actual perceived handicap may greatly vary from individual to individuals even with same or similar hearing loss characteristics. Based on perceived handicapped and associated,  which range from mild, to moderate, to sever and finally to profound hearing loss and based on the main site of the problem into Conductive, Mixed or Sensory – Neural hearing loss.