Nerve impulses and sound perception

[Acme]

With respect, I am not referring to subjective perception of an individual. What I am told by someone whose expertise is in the field of psychoacoustics that the speed of nerve transmission limits our ability to hear above 20kHz. Scientifically, could this imply that whatever sound we hear is processed and playback in our head at own biological predetermined speed?

 

Meaning what supposed to sound like a 33rpm record would sound like 10rpm to us. Since time is essentially the same then there must be significant amount of information discarded. Do I make sense?

With respect, you are referring to subjective perception. Bats can hear higher frequencies than we, but their neural signals are mammalian like ours. By the same token elephants and whales can hear lower frequencies than humans and they too are mammals. Hearing and sound are entirely perception concepts related to creatures and entirely distinct from vibrational qualities and concepts. Things sound to us as things sound to us and that's just the way it is.

[StringJunky]

 

Meaning what supposed to sound like a 33rpm record would sound like 10rpm to us. Since time is essentially the same then there must be significant amount of information discarded. Do I make sense?

This might seem counter-intuitive, but the faster something is sampled the slower it will seem, subjectively, compared to something that has a lower sample rate. Think about when you are in a fearful situation, everything seems to slow down, because your senses and brain are processing faster.

Edited March 2, 2015 by StringJunky

[Acme]

Hearing range

 

Hearing range usually describes the range of frequencies that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, though there is considerable variation between individuals, especially at high frequencies, and a gradual decline with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours. Routine investigation for hearing loss usually involves an audiogram which shows threshold levels relative to a standardised norm.

 

Several animal species are able to hear frequencies well beyond the human range. Some dolphins and bats, for example, can hear frequencies in excess of 100 kHz.

...

[CharonY]

 

With respect, I am not referring to subjective perception of an individual. What I am told by someone whose expertise is in the field of psychoacoustics that the speed of nerve transmission limits our ability to hear above 20kHz. Scientifically, could this imply that whatever sound we hear is processed and playback in our head at own biological predetermined speed?

 

Meaning what supposed to sound like a 33rpm record would sound like 10rpm to us. Since time is essentially the same then there must be significant amount of information discarded. Do I make sense?

 

That is not correct as the speed of sound propagation is a parameter (largely) independent from frequency. In order to hear a high frequency sound you do not need faster sampling, you need sensory neurons that start firing once they sense sound of that given frequency. This is in large part modulated by the stiffness of the basilar membrane withing the cochlea as well as the organization of the sensory neurons (essentially as indicated by String and Acme). So, no if your friend's example is based on a wave with the given frequency the explanation is wrong (or you misunderstood him).

 

As I tried to explain to explain earlier, it is wrong to thing of our sensory organs as the equivalent of a simple ADC or amplifier or anything of that sort, really. The transmission speed mostly only determines how fast we notice something, but we have means to increase the resolution of detection beyond that. One of the key points is that we parallelize the detection. If you must use an analogy think of several mics that work in parallel. However, all of them are tuned to a different band and have different filters. These are all processed in parallel an only in the end does a computer create a sound out of it. Moreover, the mics sample at staggered times, so that while each may only sample say every 5 ms, at almost any given time there are some that are done transmitting and are able to send data. The computer has then a much higher time resolution than the sample rate.

Edited March 2, 2015 by CharonY

[studiot]

Charon Y

If I understand you correctly you are talking about sampling rate (or the equivalent)?

I'm sorry the editor is playing silly b's at the moment and I can't type any answer, except in the quote functionIf you can

Ify you can parse this I don't mean sampling rate which is resolution, and refers to all signals.

II am referring to transients in the signal.

 

Edited March 2, 2015 by studiot

[MayIKnow?]

 

Same problem. Please try Chrome.

[studiot]

The editor seems to be working now so I can make a more coherent post.

 

There are a number of (not difficult, some even self evident) terms and ideas that need to be brought together to discuss this subject more thoroughly.

 

Steady state conditions

 

Transient conditions

 

The distinction between the information signal and the carrier (wave) and the use of the word 'signal'

 

Shannon's theorem [math]M = {\left( {1 + \frac{P}{N}} \right)^{TW}}[/math]

Buffers

 

Filters and filtering

 

Noise, signal and signal to noise

 

Multiplexing

 

Spatial signal distribution

 

The relationship between wave speed, wavelength and frequency

 

 

 

The last one plus Shannon's theorem is very important since they show that successful steady state continuous transmission of information is dependent not on the wave speed, but on the frequency of the carrier.

 

These apply to both biological and artificial systems including audio, radio and computer signals.

 

Let me know what you want me to expand on and what you are comfortable with

Edited March 2, 2015 by studiot

[StringJunky]

 

Moreover, the mics sample at staggered times, so that while each may only sample say every 5 ms, at almost any given time there are some that are done transmitting and are able to send data. The computer has then a much higher time resolution than the sample rate.

I think this analogy illustrates rhe resolution issue nicely and was trying to think last night how to express it; to no avail. Interesting subject.

Edited March 2, 2015 by StringJunky

[CharonY]

The editor seems to be working now so I can make a more coherent post.

 

There are a number of (not difficult, some even self evident) terms and ideas that need to be brought together to discuss this subject more thoroughly.

 

Steady state conditions

 

Transient conditions

 

The distinction between the information signal and the carrier (wave) and the use of the word 'signal'

 

Shannon's theorem [math]M = {\left( {1 + \frac{P}{N}} \right)^{TW}}[/math]

 

Buffers

 

Filters and filtering

 

Noise, signal and signal to noise

 

Multiplexing

 

Spatial signal distribution

 

The relationship between wave speed, wavelength and frequency

 

 

 

The last one plus Shannon's theorem is very important since they show that successful steady state continuous transmission of information is dependent not on the wave speed, but on the frequency of the carrier.

 

These apply to both biological and artificial systems including audio, radio and computer signals.

 

Let me know what you want me to expand on and what you are comfortable with

 

I am familiar with the concepts, and I do agree (and tried to express) that the wave speed is not an issue. However, I still think there is a bit of a misunderstanding about the property of the ears (as sampling frequency is more limiting than transmission speed, specifically ). How about you explain how the signal transduction works and at which point transmission will be limiting and we can try to discuss that. I think maybe the key could be the fact that one has to apply multiplexed sampling (and curiously, time information is coded in a yet slightly different mechanism by phase locked spikes).

[studiot]

@Charon Y

 

My last post was really addressed to MayIknow, although I am happy to discuss this subject with anyone.

I'm sure you understand most if not all the terms I listed, but I don't want a discussion to go over the OP's head because he doesn't know something basic.

 

Meanwhile a couple of points.

 

You seem to be concentrating on successful transmission of significant quantities of high grade data.

 

A new born baby receives at least as much signal as an older human, but cannot resolve it into intelligible signal.

Doing this is part of the story.

 

Sometimes the simple absence or presence of a sound, rather than its exact nature, is all that matters.

Hence my focus on transients.

 

A dramatic demonstation that carrier wave speed has little to do with successful steady state data transmission appears in electromagetically carried signals.

 

All EM waves travel at the same speed.

AM radio can convey continuous speech and poor quality music.

FM radio can convey high quality music.

Neither would convey information fast enough to run an internet connection.

Frequencies used in DAB (digital audio broadcasting) and PSB (public service broadcasting - wifi-) can carry significant quantities of internet data, including enough for video.

Microwaves and EM Signals in optical fibres can carry sunstantial numbers of such channels simultaneously

The ELF (extra low frequency) radio signals transmitted to submarines can only signals as coded individual words, like the old teletype, with speeds measured in minutes per word (not words per minute)

All these signals travel at the speed of light, but the capacity varies enormously with frequency.

Nevertheless the speed of an on/off transient is the same for all these signals.

[CharonY]

Oh, sorry my bad. I overlooked the post in-between (and frankly, am sleep deprived). Carry on .

[MayIKnow?]

I am sorry I could not keep the pace. I am still thinking about post #26. I am the weakest link here. I may not expressing myself well and thank you Studiot for introducing Shannon theorem. Hope that would bring closer to understand how we really decode the sound in our ears.

 

Regarding the the microphone analogy of Charon Y, does the ms abbreviation stand for millisecond? My m/s abbreviation stands for meter per second. I am thinking along a simple line; when there is a different speed on a highway there must be a bottleneck at the point where the speed slows. It is possible that all "vehicles" will get to the where it supposed to go but that would take a longer time. Sampling rate is not an issue here. It is more like mineral bottles in a conveyor where the bottleneck happens at the packaging section where the process goes on long after the conveyor machine stopped.

 

However, I am beginning to see that the delay in neuronal speed is immaterial but I just trying to simplify the concept for my simple mind.

 

I also learnt from the research conducted and published in paper titled Dogs Hearing (University of Nebraska) that dogs do hear same sound differently. I haven't read the papers but just skimping through the highlights it appears that it got more to do with the frequency bandwidth of dogs hearing.

 

In my case, it is easier to ask question without having the slightest understanding of the basics. I just came across another new terminology for another delay in the hearing process; Axonal conduction delays. More fun time reading.

Edited March 3, 2015 by MayIKnow?

[StringJunky]

ms is millisecond.

 

I would suggest you stick to learning human hearing first, and diregard other animals, otherwise you might be comparing apples to oranges and mess your learning up.

...I am thinking along a simple line; when there is a different speed on a highway there must be a bottleneck at the point where the speed slows. It is possible that all "vehicles" will get to the where it supposed to go but that would take a longer time. Sampling rate is not an issue here. It is more like mineral bottles in a conveyor where the bottleneck happens at the packaging section where the process goes on long after the conveyor machine stopped.

The problem is that the 'bottles' going into the ear canal aren't backing up, they are being taken as fast as they arrive because there is always a nerve cell - out of the 30 000 - waiting to fire.; that's where the staggered microphone analogy comes in.

[Acme]

 

I am sorry I could not keep the pace. I am still thinking about post #26. ...

ms is millisecond.

 

I would suggest you stick to learning human hearing first, and diregard other animals, otherwise you might be comparing apples to oranges and mess your learning up.

 

I strongly disagree. While the others are laying out the technical terms as well as machine analogies to signal propagation, reception, and processing the central question is about animal hearing. I think my example of bats & dolphins being able to hear frequencies of 100kHz vs. our ~20kHz limit is a good practical easy-to-understand example for clarifying the issue of speed of sound vs. frequency. Moreover as I have tried to point out, hearing is entirely an animal exercise. What better way to understand it than with [eared] animal examples?

 

Mess up learning with knowledge? Heaven forbid.

[StringJunky]

I strongly disagree. While the others are laying out the technical terms as well as machine analogies to signal propagation, reception, and processing the central question is about animal hearing. I think my example of bats & dolphins being able to hear frequencies of 100kHz vs. our ~20kHz limit is a good practical easy-to-understand example for clarifying the issue of speed of sound vs. frequency. Moreover as I have tried to point out, hearing is entirely an animal exercise. What better way to understand it than with [eared] animal examples?

 

Mess up learning with knowledge? Heaven forbid.

No criticism was inferred. There is a specific aspect that the OP is trying to grasp and I'm trying to help him zone in on that. How the information is coming and how it's captured.

[MayIKnow?]

...

The problem is that the 'bottles' going into the ear canal aren't backing up, they are being taken as fast as they arrive because there is always a nerve cell - out of the 30 000 - waiting to fire.; that's where the staggered microphone analogy comes in.

 

I cannot understand this statement based on experience. Let's say, I take a load of 1000 leaves from 10 meters away and throw it in bin asking 30000 snails to pick them up and put in in another bin. Do you expect them to accomplish this as fast as putting all the 1000 leaves directly to the second bin?

Edited March 3, 2015 by MayIKnow?

[StringJunky]

 

I cannot understand this statement based on experience. Let's say, I take a load of 1000 leaves from 10 meter away and throw it in bin asking 30000 snails to pick them up and put in in another bin. Do you expect them to accomplish this as fast as putting all the 1000 leaves directly to the second bin?

No, it doesn't matter how long the 'information' (within reason) - which is the 1000 leaves - is carried to the bin by 1000 snails. There are 29 000 snails waiting for for next load of leaves.

Edited March 3, 2015 by StringJunky

[Acme]

No criticism was inferred. There is a specific aspect that the OP is trying to grasp and I'm trying to help him zone in on that. How the information is coming and how it's captured.

No worries. I'm working to the same end. Perhaps your animals comment was in view of MayKnow's dog article comment rather than MayKnow's mention of my post #26 that referenced animals.

 

Anyway, MayKnow, what is it about post #26 that has you puzzled? Also, are you still in touch with your friend that made the hearing bottleneck comment? If so you might share this thread and/or ask for some clarification on the notion.

[MayIKnow?]

No, it doesn't matter how long the 'information' (within reason) - which is the 1000 leaves - is carried to the bin by 1000 snails. There are 29 000 snails waiting for for next load of leaves.

 

This will only work if the snails are back by the time the 31st load arrives and the duration of arrival of the load is the same as the duration for the snails to putting in the second bin and get back to the pile.

[StringJunky]

 

This will only work if the snails are back by the time the 31st load arrives and the duration of arrival of the load is the same as the duration for the snails to putting in the second bin and get back to the pile.

Yes, but you can see the principle?

No worries. I'm working to the same end. Perhaps your animals comment was in view of MayKnow's dog article comment rather than MayKnow's mention of my post #26 that referenced animals.

 

Anyway, MayKnow, what is it about post #26 that has you puzzled? Also, are you still in touch with your friend that made the hearing bottleneck comment? If so you might share this thread and/or ask for some clarification on the notion.

That's right.

[MayIKnow?]

No worries. I'm working to the same end. Perhaps your animals comment was in view of MayKnow's dog article comment rather than MayKnow's mention of my post #26 that referenced animals.

 

Anyway, MayKnow, what is it about post #26 that has you puzzled? Also, are you still in touch with your friend that made the hearing bottleneck comment? If so you might share this thread and/or ask for some clarification on the notion.

 

 

I am aware from the beginning that the post was meant for me... )

 

Anyway, my "friend" did not make those comment. I only said "What I am told by someone whose expertise is in the field of psychoacoustics that the speed of nerve transmission limits our ability to hear above 20kHz. "

 

Anyway, will try to get some clarification from him. Although, he did warn me that he knew very little about nerve function. It is not easy to approach a man in his late 80s or early 90s to ask for free lessons.

Edited March 3, 2015 by MayIKnow?

[Acme]

I am aware from the beginning that the post was meant for me... )

 

Anyway, my "friend" did not make those comment. I only said "What I am told by someone whose expertise is in the field of psychoacoustics that the speed of nerve transmission limits our ability to hear above 20kHz. "

 

 

Anyway, will try to get some clarification from him. Although, he did warn me that he knew very little about nerve function.

Roger roger. So have you achieved any satisfaction to your understanding yet through all our efforts?

Edited March 3, 2015 by Acme

[MayIKnow?]

 

Anyway, will try to get some clarification from him. Although, he did warn me that he knew very little about nerve function.

 

Roger roger. So have you achieved any clarification yet through all our efforts?

 

 

More than I ever hoped for. And I grateful to all of you guys.

 

p.s. I did edit my above post explaining the reluctance.

[StringJunky]

Here's a couple of interesting bits that support what's been said:

Temporal Theory (hearing)

 

Volley Theory

 

N.B. A 'theory' in science is the best you'll ever get.

Edited March 3, 2015 by StringJunky

[MayIKnow?]

........

 

N.B. A 'theory' in science is the best you'll ever get.

 

 

That is still evolving when it comes to understanding how our ears work.

 

Maybe this will interest you guys.

 

 

 

Recognizing that humans have a mechanism for distinguishing sounds above the theoretical limit leads to another thought: acoustic engineers might learn from the ear-brain system about how to do it. Oppenheim and Magnasco end their paper with that tantalizing idea:

 

 

Meanwhile, on reflection of what’s said in this thread, my understanding of this thread are as follows:-

 

1) Speed of sound is the speed of transfer movement of molecules to the adjacent molecules .

2) The speed got nothing to do with the oscillation of (air) molecules.

3) The frequency of the oscillation produces sound by creating sound pressure.

4) A slight vibration of 1e-8mm in the ear drum is detectable by us which is close to 0dB.

5) The eardrum membrane area is about 65 mm2.

6) The most the eardrum could travel when vibrating is not likely to exceed 0.5cm. ( I am guessing here because that’s the diameter’s of the eardrum)

7) Hair cells length is much smaller than the eardrum’s diameter.

8) When hair cells vibrate at 20kHz. The total distance in one second could not be more a few meters considering they are less than 1 mm lenght. ( Something is not right with this statement)

9) Total distance per frequency even at the max of 20kHz is still within the transmission speed of our fastest nerve system (120m/s) and therefore all information could be transferred to brain without loss.

10) However, I believe the neural transmission speed in our ears is about 8m/s only.

 

 

Am I getting closer? At least now I am clear why the speed of sound is immaterial.