<p><strong>Short answer</strong><br>
Damage to the inner ear can result in an asymmetric distortion in pitch perception between the two ears. This phenomenon can result in the same tone being perceived as a different pitch by the two ears.</p>

<p><strong>Background</strong><br>
Damage to the inner ear (the <em><a href="https://en.wikipedia.org/?title=Cochlea" rel="nofollow">cochlea</a></em>) can lead to <a href="https://en.wikipedia.org/wiki/Hearing_loss" rel="nofollow">hearing loss</a>. Hearing loss can sometimes lead to changes in perceived pitch. For people with unilateral cochlear damage, or asymmetrical hearing losses, the same tone presented alternately to the two ears may be perceived as having different pitches in the two ears (<strong><em>diplacusis</em></strong>). Sometimes different pitches are perceived even when the hearing loss is the same in the two ears <a href="https://www.google.com.au/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=1&amp;cad=rja&amp;uact=8&amp;ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&amp;url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&amp;ei=iGiBVeXwIojh8gXd-gE&amp;usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&amp;sig2=tQVz-BSeOVbfhiUuP0SngQ&amp;bvm=bv.96041959,d.dGc" rel="nofollow">(Moore, 1996)</a>. Diplacusis is associated with a higher perceived pitch in the relatively more impaired ear <a href="http://www.ncbi.nlm.nih.gov/pubmed/3711452" rel="nofollow">(Burns &amp; Turner, 1986)</a>. </p>

<p>The precise origin of these pitch shifts is unclear, but are related to hearing loss <a href="https://www.google.com.au/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=1&amp;cad=rja&amp;uact=8&amp;ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&amp;url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&amp;ei=iGiBVeXwIojh8gXd-gE&amp;usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&amp;sig2=tQVz-BSeOVbfhiUuP0SngQ&amp;bvm=bv.96041959,d.dGc" rel="nofollow">(Moore, 1996)</a>. What is known, however, is that damage to the cochlea can lead to <a href="http://link.springer.com/chapter/10.1007/0-387-28958-5_7" rel="nofollow">(Moore &amp; Carlyon, 2005)</a>:</p>

<ol>
<li><strong>Reduced frequency selectivity</strong> in the ear, i.e., a reduced pitch discrimination. This may alter the perception of pitch in complex tones; </li>
<li><strong>Altered velocity of the <a href="https://en.wikipedia.org/wiki/Basilar_membrane" rel="nofollow">travelling wave on the basilar membrane</a></strong>. When the <em><a href="https://en.wikipedia.org/wiki/Hair_cell#Outer_hair_cells_.E2.80.93_acoustical_pre-amplifiers" rel="nofollow">outer hair cells</a></em> (the acoustic amplifiers in the cochlea) are damaged, the speed in which the acoustic wave travels through the cochlea may be altered, possibly leading to an altered perceived pitch;</li>
<li><strong>Dead regions</strong> in the cochlea, where the <a href="https://en.wikipedia.org/wiki/Hair_cell#Inner_hair_cells_.E2.80.93_from_sound_to_nerve_signal" rel="nofollow">inner hair cells</a> (the mechanoreceptors of the inner ear) are absent. In this case a tone is perceived by adjacent regions in the cochlea. Because the cochlea is a frequency-to-place converter (basically a Fourier transformer), it may result in altered pitch perception; </li>
<li><strong>Reduced phase locking</strong> <a href="http://www.jneurosci.org/content/17/9/3312.full.pdf" rel="nofollow">(Koppl, 1997)</a> in the auditory nerve. Phase locking refers to auditory nerve fibers following the waveform of the tonal stimulus, which may provide pitch information (in humans this process is mainly confined to low frequencies, ~1 kHz and below). Reduction of this property may alter pitch perception.  </li>
</ol>

<p><strong>References</strong><br>
<strong>-</strong> <a href="http://www.ncbi.nlm.nih.gov/pubmed/3711452" rel="nofollow">Burns &amp; Turner, <em>JASA</em> (1986), <strong>79</strong>(5): 1530-40</a><br>
<strong>-</strong> <a href="http://www.jneurosci.org/content/17/9/3312.full.pdf" rel="nofollow">Koppl, <em>J Neurosci</em> (1997), <strong>17</strong>(9): 3312–21</a><br>
<strong>-</strong> <a href="https://www.google.com.au/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=1&amp;cad=rja&amp;uact=8&amp;ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&amp;url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&amp;ei=iGiBVeXwIojh8gXd-gE&amp;usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&amp;sig2=tQVz-BSeOVbfhiUuP0SngQ&amp;bvm=bv.96041959,d.dGc" rel="nofollow">Moore, <em>Ear Hear</em> (1996); <strong>17</strong>: 133-60</a><br>
<strong>-</strong> <a href="http://link.springer.com/chapter/10.1007/0-387-28958-5_7" rel="nofollow">Moore &amp; Carlyon, <em>Springer Handbook of Auditory Research</em> (2005); <strong>24</strong>: 234-77</a> </p>

CC BY-SA 3.0
2015-06-17T14:28:59.093Z
Top-notch answer as usual!
Krysta
CC BY-SA 3.0
2015-06-23T06:10:28.773Z
How large can the pitch be (in Hz)?
draks ...
CC BY-SA 3.0
2015-06-23T11:53:54.197Z
@draks... you mean the pitch or pitch difference?
AliceD
CC BY-SA 3.0
2015-06-23T12:50:31.427Z
Sorry, the pitch difference, please...
draks ...
CC BY-SA 3.0
2015-06-17T13:10:17.500Z
2015-06-18T02:40:38.603Z
2015-06-18T02:40:38.603Z
AliceD
<p>A patient with sensorineural hearing loss can have the symptom of hearing "double" in the damaged ear. Not having a time-delayed echo, but hearing as if he (or other people) speak with "two voices" at once. </p>

<p>Is there a theory about the mechanism behind this? Does it happen on the level of the malfunctioning hair cells, or because the brain has trouble remapping an incomplete input of frequencies, or something else? </p>

CC BY-SA 3.0
2015-06-15T12:24:36.383Z
Would you happen to have a source to this phenomenon? It sounds interesting.
AliceD
CC BY-SA 3.0
2015-06-15T13:11:37.343Z
@AliceD It's personal experience, sadly :( But the ENT wasn't surprised to hear about it, so I assumed it's common enough in his patients.
rumtscho
CC BY-SA 3.0
2015-06-15T13:17:31.980Z
@aliceD Is the site really strict enough to close a question if it was *inspired* by a personal situation when I was careful to write the main text on a theoretical level? I think I'd best ask the mods, or on Meta.
rumtscho
CC BY-SA 3.0
2015-06-15T13:19:56.597Z
Meta and mods are your best chance for sure. While we're on it: What is the hearing function like? Any hearing loss? Unilateral or bilateral? In case of hearing loss - what is the audiogram  like (high-frequency hearing loss, or a noise-dip at 4 kHz, or other)? Is the double-voice phenomenon temporary (say a few minutes at a time, or only after a loud concert, or is it chronic and persistent)?
AliceD
CC BY-SA 3.0
2015-06-15T13:36:29.813Z
@AliceD in my case, it's unilateral, current diagnosis ISSHL. Audiogram looks roughly like a sigmoid function, lots of hearing loss in the low frequencies, almost all good in the high ones, steep slope in the middle. The double hearing symptom changes all the time, it can be completely absent, or only appear on my own voice, or only on female voices, or on all voices. It rarely if ever appears on "brumm" type noises like traffic or computer fan. I don't know if other people experience it in a similar way.
rumtscho
CC BY-SA 3.0
2015-06-15T13:37:55.400Z
Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/24836/discussion-between-rumtscho-and-aliced).
rumtscho
<neuroscience><perception><cognitive-neuroscience>
What is the neurophysiological mechanism behind double hearing?
rumtscho
# What is the neurophysiological mechanism behind double hearing?

(Asked by: username_0 on 2015-06-15)

A patient with sensorineural hearing loss can have the symptom of hearing "double" in the damaged ear. Not having a time-delayed echo, but hearing as if he (or other people) speak with "two voices" at once.

Is there a theory about the mechanism behind this? Does it happen on the level of the malfunctioning hair cells, or because the brain has trouble remapping an incomplete input of frequencies, or something else?

**Tags:** neuroscience, perception, cognitive-neuroscience

> **Comments:**
> **username_1**: Would you happen to have a source to this phenomenon? It sounds interesting.  
> **username_0**: @username_1 It's personal experience, sadly :( But the ENT wasn't surprised to hear about it, so I assumed it's common enough in his patients.  
> **username_0**: @aliceD Is the site really strict enough to close a question if it was *inspired* by a personal situation when I was careful to write the main text on a theoretical level? I think I'd best ask the mods, or on Meta.  
> **username_1**: Meta and mods are your best chance for sure. While we're on it: What is the hearing function like? Any hearing loss? Unilateral or bilateral? In case of hearing loss - what is the audiogram  like (high-frequency hearing loss, or a noise-dip at 4 kHz, or other)? Is the double-voice phenomenon temporary (say a few minutes at a time, or only after a loud concert, or is it chronic and persistent)?  
> **username_0**: @username_1 in my case, it's unilateral, current diagnosis ISSHL. Audiogram looks roughly like a sigmoid function, lots of hearing loss in the low frequencies, almost all good in the high ones, steep slope in the middle. The double hearing symptom changes all the time, it can be completely absent, or only appear on my own voice, or only on female voices, or on all voices. It rarely if ever appears on "brumm" type noises like traffic or computer fan. I don't know if other people experience it in a similar way.  
> **username_0**: Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/24836/discussion-between-username_0-and-aliced).  

---

## 1 answers

### Answer by username_1 on 2015-06-17. Score: 7

**Short answer**  
Damage to the inner ear can result in an asymmetric distortion in pitch perception between the two ears. This phenomenon can result in the same tone being perceived as a different pitch by the two ears.

**Background**  
Damage to the inner ear (the *[cochlea](https://en.wikipedia.org/?title=Cochlea)*) can lead to [hearing loss](https://en.wikipedia.org/wiki/Hearing_loss). Hearing loss can sometimes lead to changes in perceived pitch. For people with unilateral cochlear damage, or asymmetrical hearing losses, the same tone presented alternately to the two ears may be perceived as having different pitches in the two ears (***diplacusis***). Sometimes different pitches are perceived even when the hearing loss is the same in the two ears [(Moore, 1996)](https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&ei=iGiBVeXwIojh8gXd-gE&usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&sig2=tQVz-BSeOVbfhiUuP0SngQ&bvm=bv.96041959,d.dGc). Diplacusis is associated with a higher perceived pitch in the relatively more impaired ear [(Burns & Turner, 1986)](http://www.ncbi.nlm.nih.gov/pubmed/3711452).

The precise origin of these pitch shifts is unclear, but are related to hearing loss [(Moore, 1996)](https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&ei=iGiBVeXwIojh8gXd-gE&usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&sig2=tQVz-BSeOVbfhiUuP0SngQ&bvm=bv.96041959,d.dGc). What is known, however, is that damage to the cochlea can lead to [(Moore & Carlyon, 2005)](http://link.springer.com/chapter/10.1007/0-387-28958-5_7):

1. **Reduced frequency selectivity** in the ear, i.e., a reduced pitch discrimination. This may alter the perception of pitch in complex tones;
2. **Altered velocity of the [travelling wave on the basilar membrane](https://en.wikipedia.org/wiki/Basilar_membrane)**. When the *[outer hair cells](https://en.wikipedia.org/wiki/Hair_cell#Outer_hair_cells_.E2.80.93_acoustical_pre-amplifiers)* (the acoustic amplifiers in the cochlea) are damaged, the speed in which the acoustic wave travels through the cochlea may be altered, possibly leading to an altered perceived pitch;
3. **Dead regions** in the cochlea, where the [inner hair cells](https://en.wikipedia.org/wiki/Hair_cell#Inner_hair_cells_.E2.80.93_from_sound_to_nerve_signal) (the mechanoreceptors of the inner ear) are absent. In this case a tone is perceived by adjacent regions in the cochlea. Because the cochlea is a frequency-to-place converter (basically a Fourier transformer), it may result in altered pitch perception;
4. **Reduced phase locking** [(Koppl, 1997)](http://www.jneurosci.org/content/17/9/3312.full.pdf) in the auditory nerve. Phase locking refers to auditory nerve fibers following the waveform of the tonal stimulus, which may provide pitch information (in humans this process is mainly confined to low frequencies, ~1 kHz and below). Reduction of this property may alter pitch perception.

**References**  
**-** [Burns & Turner, *JASA* (1986), **79**(5): 1530-40](http://www.ncbi.nlm.nih.gov/pubmed/3711452)  
**-** [Koppl, *J Neurosci* (1997), **17**(9): 3312–21](http://www.jneurosci.org/content/17/9/3312.full.pdf)  
**-** [Moore, *Ear Hear* (1996); **17**: 133-60](https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCMQFjAAahUKEwjl1Lfq3ZbGAhWIsLwKHV19AAA&url=http%3A%2F%2Fwww.phon.ucl.ac.uk%2Fcourses%2Fspsci%2FAUDL4007%2FMoore%25201996%2520Ear%2520%26%2520Hearing.pdf&ei=iGiBVeXwIojh8gXd-gE&usg=AFQjCNHhYgO35s8Un7D-xDEtN9TsSHygTw&sig2=tQVz-BSeOVbfhiUuP0SngQ&bvm=bv.96041959,d.dGc)  
**-** [Moore & Carlyon, *Springer Handbook of Auditory Research* (2005); **24**: 234-77](http://link.springer.com/chapter/10.1007/0-387-28958-5_7)

> **Comments:**
> **username_2**: Top-notch answer as usual!  
> **username_3**: How large can the pitch be (in Hz)?  
> **username_1**: @draks... you mean the pitch or pitch difference?  
> **username_3**: Sorry, the pitch difference, please...  

---

