Evaluating the Function of the Medial Olivocochlear Bundle in Patients with Bilateral Tinnitus

[Juan]

Evaluating the Function of the Medial Olivocochlear Bundle in Patients With Bilateral Tinnitus

Abstract
Purpose
No study has investigated the effects of contralateral noise (CN) on speech-in-noise perception (SINP) in listeners with tinnitus. The mechanisms underlying the involvement of medial olivocochlear (MOC) reflex with SINP remain to be elucidated. This study aimed to investigate the MOC function in patients with bilateral tinnitus by measuring distortion product otoacoustic emission and SINP.

Method
Eighteen patients with bilateral tinnitus (one male and 17 females; age: M ± SD = 45.61 ± 10.18 years) and 19 listeners without tinnitus (six males and 13 females; age: M ± SD = 34.11 ± 8.35 years) were recruited for the study. Each subject underwent distortion product otoacoustic emission measurement and the SINP test for both ears. The effects of CN on these two measurements were compared between tinnitus ears (TEs) and no-tinnitus ears (NTEs).

Results
The presence of CN significantly reduced distortion product (DP) amplitudes and improved SINP for TEs, and the amounts of DP suppression and SINP improvement were similar to those in NTEs. Improvement of SINP was positively correlated with DP suppression at 6185 Hz for NTEs and at 1640 Hz for TEs.

Conclusions
The results of this study suggest that the amounts of DP suppression and SINP improvement were similar between listeners with and without tinnitus. For both ear groups, the MOC reflex was involved with SINP at specific frequencies. Any clinical test outcomes with regard to the MOC bundle in patients with tinnitus should be interpreted with caution until further studies are conducted.

https://pubs.asha.org/doi/full/10.1044/2020_JSLHR-19-00080

 

[FGG]

Evaluating the Function of the Medial Olivocochlear Bundle in Patients With Bilateral Tinnitus

Abstract
Purpose
No study has investigated the effects of contralateral noise (CN) on speech-in-noise perception (SINP) in listeners with tinnitus. The mechanisms underlying the involvement of medial olivocochlear (MOC) reflex with SINP remain to be elucidated. This study aimed to investigate the MOC function in patients with bilateral tinnitus by measuring distortion product otoacoustic emission and SINP.

Method
Eighteen patients with bilateral tinnitus (one male and 17 females; age: M ± SD = 45.61 ± 10.18 years) and 19 listeners without tinnitus (six males and 13 females; age: M ± SD = 34.11 ± 8.35 years) were recruited for the study. Each subject underwent distortion product otoacoustic emission measurement and the SINP test for both ears. The effects of CN on these two measurements were compared between tinnitus ears (TEs) and no-tinnitus ears (NTEs).

Results
The presence of CN significantly reduced distortion product (DP) amplitudes and improved SINP for TEs, and the amounts of DP suppression and SINP improvement were similar to those in NTEs. Improvement of SINP was positively correlated with DP suppression at 6185 Hz for NTEs and at 1640 Hz for TEs.

Conclusions
The results of this study suggest that the amounts of DP suppression and SINP improvement were similar between listeners with and without tinnitus. For both ear groups, the MOC reflex was involved with SINP at specific frequencies. Any clinical test outcomes with regard to the MOC bundle in patients with tinnitus should be interpreted with caution until further studies are conducted.

https://pubs.asha.org/doi/full/10.1044/2020_JSLHR-19-00080

MOC seems to help with "selective listening". It's an efferent nerve from the brain to the cochlea. Ever wonder why you can singly tune in or tune out certain environmental sounds to focus more on others? That's your MOC system using creating a stronger signal from some hair cells vs. others.

It's neat they can measure this by testing your speech in noise while giving sound in the other ear (MOC can also dampen loud noise a bit and it works in unison bilaterally--which might be why the tested it imo, to see if a strong reflex protected some people from getting tinnitus). I didn't know there was testing for this.

Behind a payroll but going by the abstract, this study at least says that it seems unrelated but was pretty interesting I thought.

 

[Juan]

MOC seems to help with "selective listening". It's an efferent nerve from the brain to the cochlea. Ever wonder why you can singly tune in or tune out certain environmental sounds to focus more on others? That's your MOC system using creating a stronger signal from some hair cells vs. others.

It's neat they can measure this by testing your speech in noise while giving sound in the other ear (MOC can also dampen loud noise a bit and it works in unison bilaterally--which might be why the tested it imo, to see if a strong reflex protected some people from getting tinnitus). I didn't know there was testing for this.

Behind a payroll but going by the abstract, this study at least says that it seems unrelated but was pretty interesting I thought.

Yes, I also thought it is interesting. It would be great to be able to read the full text for free.

Sometimes I feel like there is something at the centre of my neck that balances the input of sound that every ear gets. Probably this is just a personal feeling, but in the past I wondered if this had to do with the olivocochlear bundle..

As for "selective listening", I have a lot of theories for that. As a kid, I would be at the classroom, looking out of the window, and with my mind wandering in its own world. Well, teachers would tell me "are you paying attention? what did I just say?" and I would be able to repeat exactly what they were saying and discussing. For me examples like this prove that there is no such thing as focusing on sounds or verbal information to get a better understanding or to listen better in background noise. Focusing makes no difference. The ability to recognise speech in noise, and gathering speech information when not paying attention is something purely physical and biological, it does not have to do with processing but with pure and sharp hearing ability, a physical and biological trait individual for each person.

I read abstracts of other articles on olivocochlear response, and they tested this with ABRs (evoked potentials, I think)... that's a loud test. Distortion products are not loud at all, it is just like a low eerie "flying saucer" sound in your ears haha.