Temporary Threshold Shift and Further Damage?

[sven1987]

Has anyone here ever experienced a temporary threshold shift after getting tinnitus and as a result making it worse?

I'm asking this, because 2 weeks ago at work I was checking out a delivery of steel platings with a coworker and he dropped a steel plate of about 25 pounds on another steel plate from about a height of 8 inches. I was standing about 2 feet away. As soon as the plate dropped I got fullness and increased ringing in my left ear, with the ringing subsiding after a few seconds and the fullness lasting another 2 minutes or so.

My coworker also experienced this as he commented about his ears ringing for a few seconds.

The problem is though that my left ear has been spiking for 2 weeks and I'm wondering if I've screwed up my hearing further. My reactivity to certain sounds has also increased, making my ears ring a lot more than before.

 

[Alue]

I'm curious if the spike ever went away.

 

[Digital Doc]

2 weeks is not that long for a spike to persist. I was exposed to an air horn in a parking lot, several car lengths away, and it took around 2 months to go away.

Key is to do your best protecting from exposure to additional noise.

 

[Contrast]

The science on how temporary threshold shifts have changed. Hair cells can survive some cases of noise trauma but cochlear nerves are more fragile and they can be lost permanently in a temporary theshold shift.

http://www.hearingreview.com/2017/02/temporary-threshold-shift-tts-not-temporary/
Conclusions of many researchers in the last century, such as those of Dixon Ward,1 Erik Borg,3 and colleagues suggest that there are no lasting effects of TTS, and that it is a benign side effect of overexposure. The most that could be said is that, prior to having a permanent noise or music related hearing loss, one first needed to experience TTS.

This new century brought with it measures of TTS that go beyond the simple pure-tone audiogram; specifically, suprathreshold neural structures. Research by Kujawa and Liberman4,5 and others have demonstrated that, while cochlear function (and puretone hearing loss) does resolve after TTS, neural pathology can remain. Specifically it was found that, even after puretone thresholds have returned to a pre-exposure state, there can still be:

1. Rapid inner hair cell (afferent) synaptic loss;
2. Rapid inner hair cell dendritic loss;
3. Slow spiral ganglion cell loss, and
4. Persistent reductions in suprathreshold neural responses (ie, reduced wave I ABR).

Temporary hearing loss can no longer be considered to be a benign temporary audiometric characteristic. Although it has not been established that TTS can be a predictor of future hearing loss, its presence does point to sometimes subtle neural pathologies that may result in future communication degradation.


direct scientific study
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4567542/

 

[Alue]

@Contrast
Also the older study here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812055.
With this knowledge one would think regulatory agencies such as OSHA and NIOSH should update the guidelines for what is considered a safe noise exposure level. The OSHA guidelines that everyone likes to quote were based on permanent threshold shifts in 2kHz, 3kHz, or 4kHz. It's just laughable that people still quote them saying it's safe to be in 90db for up to 8 hours a day.