HOW DO WE HEAR ?
Laird Snowden
HELIOS, AHEL, IFPIC AT&T Bell Labs SONET CHIP SET. VFMA Wafer scale test , High Energy Laser Weapons, Millimeter Wave, Senior Electro-Optical Manager, Process & Electrical Engineer High Energy Projected Beam Weapons
Our perception of Music, what is music:
well, i was just reading an old sermon by John Alexander, he stated in one part that there is music in Heaven, but nothing like on earth.
Many years ago i worked on software to identify spurious M by N signals in radar signals used in electronic warfare. So i understand envelopes in time and the frequency domain.
Audio is the same, just a much lower frequency.
When i was at Bell Labs, i did some preliminary work on modeling the human brain, as i had used Neural Networks to analyze non-orthogonal high dimensionality data. I could go on more but i will digress to a interesting things i learned about the human audio cortex.
By the way, i have a sound retrieval system developed by Hughes Aircraft based on transforming radar signal processing to the function of the human ear. It uses transfer functions to cause frequency selective phase delays to reposition the sound field, i have also added some other things to restore the phase delay cues that would be present in wet sampling rather than dry or anechoic sampling and restores the dynamic range lost in the recording media..
Have you noticed you have only two ears (i know you probably noticed this) what i mean to say is that you can discern the source of audio from a point equidistant between your ears in front of you and behind you. Completely impossible for a scalar value with only two reception points. What is needed is another value, a vector rather than a scalar value to account for this. The vector is actually phase. Your ear canal is actually an audio waveguide. Sound impinges on either the front of your ear or on the back of it, depending on the direction of the wavefront. All sounds in nature are composed of a fundamental frequency and sub harmonics which create an audio envelope which accounts for the difference between a cricket or a bird or the timbre of a woodwind, and differentiates it from a trumpet of french horn or piano. These different frequencies propegate down the ear canal, the angle of reflection and thus the total length of the path is dependent on the frequency and the wavefront arrive at the ear drum at slightly offset times and those times will be different depending on whether the wavefront first impinged on the back of your ear or the front, as the coefficient of reflection will be slightly different. This by the way is why your ear has all those strange ridges on the outside . Everyone's twisty ear canal is differently shaped, so directionality is something you must learn as an infant.
So now we have accounted for directional detection. Here is where it gets very interesting. Your audio cortex must tag the subharmonics with the frequency AND delay time to the fundamental frequency. From this your higher process can tell which side of your ear drum was impinged upon first by the audio wavefront. BUT, you can discriminate between simultaneous sounds originating in front of you and behind you.
This requires an adaptive identification of different subharmonics to their associated fundamental frequencies. Now the computing is getting very complex.
It gets worse, a trumpet playing a C chord, a french horn playing the same chord and a violin also playing the same chord are all have subharmonics correctly correlated with the direction of the correct fundamental. The location of the instruments does not change as they sweep their notes, this is what would happen if the fundamentals were not perfectly correlated to their subharmonics, the french horn would jump to the trumpet position if the correlation slipped for those two sounds. In addition, when notes overlap, there is not discontinuity, even as frequencies are crossing each other. In fact you would just hear noise without subharmonic to fundamental correlation as this is what forms the sound envelope of each instrument... It is your hearing that provides this miracle> man could never invent instruments or music unless God gave you the ability to hear them first... the first symphonies existed before music in the world, and came from wind, leaves suserating, birds singing....
Now this is truly amazing. Your brain now knows the proper fundamental and the proper subharmonic and it tracks them all together as they are all changing in different directions and is keeping them all perfectly associated.
You learned this as an infant, based on the structure of your outer ear, which is responsible for the diverse paths and thus time delay as a function of where the sound wave first strikes your outer ear, which is a function of direction. Since your ear canal is all twisty, each sound wave takes a different path depending on where (from what direction) it first strikes your outer ear. Thus arriving at different time delays as a function of frequency (higher frequency has a longer path and thus a slightly different delay with respect to lower frequencies... the delta between these frequencies is what determins direction as the point of first reflection impact of the sound wave to your outer ear direct the sound wave down your ear canal (audio waveguide) by a dependent different path, dependent on direction of first intercept between sound wave and outer ear.
so you can triangulate with only two ears, by the addition of an extra piece of information, frequency dependent phase delay.
By the way, as a further proof of concept, if you have ever heard a pure sinewave with no sub harmonics such as some sonalerts, the sound will seem to be coming from every direction at once, because the audio cortex can not create a vector form a purely scalar value.
Why i say that there most certainly is music in Heaven as on earth, if you do Believe in God, He created man, He created mans audio cortex, He created the concept of music, music is art, like a beautiful sunset, it captures the emotion.
a violin sounds like a violin because your audio cortex can recognize and associated the fundamental and subharmonics. But this is still not why the violin sounds like a violin, because these are just numbers, frequencies with phase and amplitude relations, yes, i left out amplitude of the sub harmonics, three level vector. Your pereption occurs in your higher function, your enjoyment occurs by the union of your mind to either that which is good or that which is evil Now i will not judge which music is which, that is up to the individual and you will have to search your own heart for the answer. It is a long path from a note to how you perceive that note.
The sound of those fundamentals and subharmonics is actually created in your brain, in reality this are just frequencies and numbers, your brain 'paints' the essence, the meaning of those numbers so that you can perceive them, but your brain is a machine, it is neutral to the music it neither enjoys nor dislike the painting of the sound, this occurs only in the union of your brain, your collective thoughts AND your spirit, this is your soul, this is the thing you create.
One more bit of trivia. Your ear is both passive and active. Below about 40 dB, your ear is actually amplifying sound. The little hairs that connect the ear drum to the inner ear, reflexivelt extend when impacted by lower level wave fronts. ABove 40 dB , they passively couple the wavefront.
This is why there is a loudness button on amplifiers that boost the bass. Because in the active mode, your ear has a reduced low frequency sensitivity.
One other important detail. listening to loud music for extended periods will damage the hairs that connect the inner ear to the outer ear, permanently. It will break this wonderful system and that is tragic.
This is proof by design, the one who designed our ears, who breathed His Spirit into us and who want to walk with us.
I also heard someone who claimed to have been in Heaven and return say that he heard beautiful symphonies as on earth being sung by angels also music of a type he had never heard before. I find that easy to believe. God would never go to all of the trouble to create this beauty and then just throw it all away and tear it down, only man comes up with dumb ideas like that. Well, i was impressed by this functionality anyhow. something as seemingly simple as hearing. color and the visual cortex is another miracle of complexity.
So our perception of music is not in the music itself, this is just a set of sequenced numbers, detected frequencies and associated sub harmonics frequencies and amplitudes. Our mind ultimately ultimately recognizes these sounds as pleasant. The trumpet was not invented by man, it was fist invented by God in the way the mind perceives these sound envelopes, man just discovered what produced that pleasant sound he was first given the ability to perceive, otherwise he would just hear a screechy fundamental and a whole bunch of noise.
All this is still mechanical, it is just a processor defining perceptions or higher structures out of these component structures.
The enjoyment, the art, the beauty can only be perceived in the soul, the union of mind and spirit. This is man God made him that way, this says something about man and also about God. So yes, there is music in Heaven, a lot of it is here right now.