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Electrical/mechanical representation of instruments and space

Help, I'm stuck at the juncture of physics, mechanics, electricity, psycho-acoustics, and the magic of music.

I understand that the distinctive sound of a note played by an instrument consists of a fundamental frequency plus a particular combination of overtones in varying amplitudes and the combination can be graphed as a particular, nuanced  two-dimensional waveform shape.  Then you add a second instrument playing, say, a third above the note of the other instrument, and it's unique waveform shape represents that instrument's sound.  When I'm in the room with both instruments, I hear two instruments because my ear (rather two ears, separated by the width of my head) can discern that there are two sound sources.  But let's think about recording those sounds with a single microphone.  The microphone's diaphragm moves and converts changes in air pressure to an electrical signal.  The microphone is hearing a single set of air pressure changes, consisting of a single, combined wave from both instruments.  And the air pressure changes occur in two domains, frequency and amplitude (sure, it's a very complicated interaction, but still capable of being graphed in two dimensions). Now we record the sound, converting it to electrical energy, stored in some analog or digital format.  Next, we play it back, converting the stored information to electrical and then mechanical energy, manipulating the air pressure in my listening room (let's play it in mono from a single full-range speaker for simplicity).  How can a single waveform, emanating from a single point source, convey the sound of two instruments, maybe even in a convincing 3D space?  The speaker conveys amplitude and frequency only, right?  So, what is it about amplitude or frequency that carries spatial information for two instruments/sound sources?  And of course, that is the simplest example I can design.  How does a single mechanical system, transmitting only variations in amplitude and frequency, convey an entire orchestra and choir as separate sound sources, each with it's unique tonal character?  And then add to that the waveforms of reflected sounds that create a sense of space and position for each of the many sound sources?

77jovian

Showing 1 response by ivan_nosnibor

ivan_nosnibor's avatar
ivan_nosnibor
1,047 posts
 

As per Geoff’s questions:

Sometimes I think of a given system hardware as a ‘doorway’ that the signal will try to go through unscathed, but is compromised along the way by 2 things at least: noise and distortion. Sometimes I wonder what it might be like if we could, say, just flip a switch and reduce All noise that could actually affect the signal, regardless of source, by an infinite amount and listen to the result. I imagine everybody, if they could do it, would be like blown away at not only the quality of reproduction, but also struck I think by how Everything sounds the Same (no more obvious differences anymore between brands, price ranges, tubes and ss, digital and analog, wiring, fuses, directionality of same, etc, etc)...I’m thinking it might all sound amazing and all of it sound overwhelmingly similar in doing so...far more like the real thing and all that.

I just know I can’t prove it, lol. But, the thought does keep coming back to me on occasion.

Q: Can mega-expensive speaker wires that have been successfully implemented into a system, for example, be thought of as simply the result of a happy, ‘random accident’ of the interplay between system, wires and (most importantly here) *noise*? IOW, could the idea of eliminating all noise mean the elimination of any need by anyone for pricey wires at all? AND, can these same cables then be thought of as justified only in systems **that are dominated by noise** (currently all systems)?

AFAIC, you’re asking the right questions, I just don’t have the right answers.

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