The AudioNotch Tinnitus Treatment Blog

Tinnitus but No Detectable Hearing Loss? You May Still Have Hearing Loss.

The development of tinnitus has a strong association with hearing loss. The association is so strong that many researchers believe that hearing loss is the most common cause of tinnitus – the evidence is very strong on this point.

However, some individuals have “normal” audiograms that have no detectable hearing loss on them, yet they still have tinnitus. These individuals typically also do not have any identifiable cause for their tinnitus.

It’s a puzzle, particularly given that most of the models we have to explain the development of tinnitus start with noise induced hearing loss.

But what if people with normal audiograms had undetectable hearing loss?

Audiograms measure the “bottom” or “low” threshold of hearing by playing very quiet tones and then increasing the volume until they are detected.

However, audiograms assume that hearing loss occurs in an upwardsstep wise fashion.

It turns out that there are different neurons that detect sound at a high volume threshold – and these are not tested in an audiogram.

An excellent paper explains the experiments done in animal models that confirm this phenomenon:

Overexposure to intense sound can cause temporary or permanent hearing loss. Postexposure recovery of threshold sensitivity has been assumed to indicate reversal of damage to delicate mechano-sensory and neural structures of the inner ear and no persistent or delayed consequences for auditory function.

Here, we show, using cochlear functional assays and confocal imaging of the inner ear in mouse, that acoustic overexposures causing moderate, but completely reversible, threshold elevation leave cochlear sensory cells intact, but cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve.

Results suggest that noise-induced damage to the ear has progressive consequences that are considerably more widespread than are revealed by conventional threshold testing. This primary neurodegeneration should add to difficulties hearing in noisy environments, and could contribute to tinnitus, hyperacusis, and other perceptual anomalies commonly associated with inner ear damage.

Translated, this means:

  • You can have a normal audiogram and damage to your auditory perception. This is why people with normal audiograms may have developed tinnitus – they may have undetected damage to their auditory system.

Science continues to change our understanding of tinnitus at a rapid rate.

Best,
AudioNotch

4 Responses to “Tinnitus but No Detectable Hearing Loss? You May Still Have Hearing Loss.”

  1. Brandon McBride said:

    Jun 14, 13 at 7:08 pm

    I don’t have many issues with Tinnitus, but I do have moments where I can’t hear something I swear I should have been able to hear. Noise is a problem in my life – I’m wondering if I have minor noise-induced hearing loss.

  2. Andres said:

    Jun 20, 13 at 4:27 pm

    My audiograms are completely normal in normal test till 8khz and other test at higher than 8khz. I have a very high pitched tinnitus like 13khz. It appeared after drinking lots of alcohol and smoking cigarretes. Im not a regular drinker or smoker. I suspect neurodegeneration ocurred due to ototoxicity. Before this, i had a 4khz almost unnoticeable unilateral tinnitus that was gone with amitriptyline. 2 days after taking amitriptilyne the tinnitus changed to this 13khz or so bilateral moderate tinnitus along with the alcohol and smoking event described.
    i suspect it id damage due to sound also because 5 days ago a fire alarm elevated my level of tinnitus.
    The theory described in this blog makes complete sense.

  3. Peter said:

    Jun 26, 13 at 9:28 pm

    Andres – you’re the type of person that we were hoping to reach with this post. Glad to have helped possibly explain your story a bit better.

  4. Guest Article: Notched Sound Therapy as a Treatment for Tinnitus: A Guide for Hearing Professionals | The Hearing Blog said:

    Aug 14, 13 at 12:32 am

    […] • Along these lines, in correspondence after his submission Dr Phua pointed out there  are some individuals who have “normal” audiograms which have no detectable hearing loss shown on them, yet these patients still have tinnitus. These individuals also typically do not have any identifiable cause for their tinnitus. However, this begs the question, what if people who present with normal audiograms have undetectable hearing loss?  Phua points out the following theory: […]


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