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I'm coming from the idea that the way we perceive sound is a reaction to a certain signal, sent to our brain by ears. Of course this feeling intensifies as volume of the sound increases and our ears send us a stronger signal.

Now here I am wondering if we can augment that signal in our brain, so when the volume stays the same - we will be able to perceive it louder. Can that be done without any kind of chemical or surgical intrusion, just by sheer force of will? Do such perception "controllers" even exist and we just haven't learned to control them? This question is about auditory system, but since it touches the brain signal interpretation you could explain this from a different perspective (visual or even tactile).

This isn't part of the question, but I also wonder, if previous is possible, than can the same be done to mentally create sounds in your head and hear them as if they were real..?

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  • $\begingroup$ I think that attention can lead to intensification of the signal, i.e., purely subjective. Objectively, it is not possible to alter spike rates of the auditory nerve and other low-level structures. Perhaps at the higher cortical level attention may start to play a role and perceived loudness may be affected. Mentally hearing sounds as if they were real - we can imagine hearing sounds and seeing things and we simply know it is not real! Psychotic folks and tinnitus patients, on the other hand, do hear voices and sounds that are not real, but that's spontaneous, so I don't think it can be done. $\endgroup$ – AliceD Dec 13 '14 at 12:16
  • $\begingroup$ @ChrisStronks but if they can hear it spontaneously and it's not some kind of chemical reaction, then it could be possible, in theory? $\endgroup$ – Rusty Dec 13 '14 at 13:24
  • $\begingroup$ @ChrisStronks some people with tinnitus can modulate the pitch/loudness of the tinnitus. $\endgroup$ – StrongBad Dec 13 '14 at 19:29
  • $\begingroup$ @StrongBad but I believe tinnitus is a physiological disorder, not psychological? I mean they can probably modulate it by straining some internal muscules, but that is hardly useful and probably more harm than good. $\endgroup$ – Rusty Dec 13 '14 at 21:57
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    $\begingroup$ Ugh, well I see from the accepted answer that you got somewhere close to where you wanted. But, it is important to remember that we understand very little about how the brain functions under normal conditions, and almost nothing about how it functions under abnormal conditions. So, I guess I don't see much value in asking such a broad question likely only to solicit opinion and conjecture. $\endgroup$ – theMayer Dec 16 '14 at 17:29
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Imagine a music recording studio, with a band playing in the soundproof room. Now imagine 2 mic->speaker connections: A mic inside the room records the music, and plays it on a speaker outside, and then another mic records the sound coming out of that speaker, and delivers it to the recording equipment. You can imagine the loss of quality involved in that set up I'm sure, but bear with me. Both mic->speaker connections are set to 50% volume. Say we want to increase the volume: We can increase the volume on either connection (or both). If we increase the volume to 100% on only one of the 2 connections, then the volume of the recorded sound will increase by approximately the same amount whichever one we choose. However, increasing the volume of the first connection is better - it results in a better quality recording. This is because each connection can only lose quality, not add it.

Now, supposing that the first mic->speaker connection represents the auditory nerve (ear -> primary auditory cortex), and the second connection represents "perception" (auditory cortex -> rest of brain), then we can discuss increasing the "volume" at either "connection" via conscious control (I'm assuming that this is what you mean by "force of will").

The auditory nerve passes through the central auditory system, an area of the brain considered unconscious:

Damage to the Primary Auditory Cortex in humans leads to a loss of any awareness of sound, but an ability to react reflexively to sounds remains as there is a great deal of subcortical processing in the auditory brainstem and midbrain.

In other words, so far as we know, there is no conscious control over this "connection".

Neuroplasticity of "perception" is much greater. A variety of studies have shown certain improved hearing capabilities in blind people, correlating with how early hearing loss occurs (the earlier the better), and the involvement of neuroplasticity as the visual cortex can be usurped for auditory processing. Whether or not this corresponds to a change in "volume" is unclear, and this effect does not appear to be "consciously" controlled.

However, more recent research has demonstrated how similar effects can be induced in non-blind adults: Through temporary blindness (as little as 90 minutes with a blindfold). Corresponding research on mice has shown that this may be the result of increased "volume" in perception:

The cells fired faster and more powerfully in response to sounds and were more sensitive to quiet sounds.

So not exactly "sheer will", but temporary blindness, that you can easily induce on yourself consciously, may improve certain aspects of hearing, possibly including "volume".

Hope this helps.

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  • $\begingroup$ This definitely helps, gives me enough directions to research for a while. I am yet to understand how psychotic people hear\see non-existing sounds\objects though. I don't believe it's brain damage, but I haven't looked into the topic too much yet. $\endgroup$ – Rusty Dec 16 '14 at 9:32
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We can easily alter the signal that arrives at the eardrum by changing our position/orientation relative to the sound source (and any reflections and any noise sources). If we limit ourselves to cases where the sound pressure at the ear drum is identical, there are still things that can be done. For example, it might be possible to voluntarily control the middle ear reflex which changes the transfer function characteristics of the middle ear and can change the sound level by approximately 20 dB. If we further limit ourselves to cases where the pressure at the stapes is identical, there are things that affect the transmission properties of the ear. The olivocochlear system is thought to control the gain properties of the cochlear amplifier. While I am not aware of any studies that have demonstrated conscious control of the oliviocochlear system, it is definitely possible through surgery and likely drugs. Our auditory perception is also driven by the chemical composition of the fluid in the cochlea and neurotransmitter reserves in the auditory nerve. It seems less likely that we could consciously control these chemical states, but surgery and drugs definitely can alter them.

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  • $\begingroup$ While this is definetly some interesting information, I was wondering about a more mental aspect of hearing. If we were to directly control (somehow, theoretically) our internal ear organs to let more sound in, it could damage the ear the same way as it damages the ear to listen to really loud sounds. But I believe it could be possible to change the way we feel the sound... Somewhere between brain recieveing a sound signal and us recognizing its volume and characteristics. There would be no threat, other than some psychological disorders, to increase the intensity of the signal here... $\endgroup$ – Rusty Dec 13 '14 at 19:02
  • $\begingroup$ @Rusty The things I mention modulate the gain prior to transduction in the "internal ear organs". Are you asking about things post transduction? $\endgroup$ – StrongBad Dec 13 '14 at 19:29
  • $\begingroup$ Yes, that's what I was asking. It's hard to explain what I meant, so I don't blame you, and things you mentioned are an interesting read as well. $\endgroup$ – Rusty Dec 13 '14 at 21:53

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