Calm down, Mr. Bluster. 😤 You’re getting all worked up.
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?
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?
Showing 7 responses by geoffkait
That is what I said, Mr. Eels. Try to calm down. 🤪 Ever heard of Valium? But getting back to the question posed by the OP, what the speakers produce is a function of the electronics, cabling, power cord, fuse, room treatments - everything. So obviously the ability to produce the full orchestra with all the details including the venue acoustic information in a coherent audio waveform without the usual distortion and noise is a huge challenge. I know what some of you are thinking - What noise and distortion? 😳 |
No, actually that’s not what Richard Feynman famously said. That’s not even close. What he said was, “If I could explain it to the average person they wouldn’t have given me a Nobel prize.” I hate to judge before all the facts are in but it certainly looks like millercarbon is the average person he was talking about. 🤡 |
roberttcan I could be wrong, but I don’t think that is what the OP is talking about at all. Not even close. I could be wrong, but I am pretty sure the op is asking how just one amplitude varying signal in the time domain can represent a whole orchestra and all its instruments. The answer to that is it doesn’t convey the whole orchestra, the brain extracts all the instruments out of the signal based on pattern recognition. >>>>That is patently absurd. Yes, you’re right, you could be wrong. |
So, I’ll ask again, how is the audio signal in cables and electronics affected by external forces such as RF and vibration as well as by better cables? And what IS the audio signal? Anybody! Is it electrons? Photons? Current? Voltage? An electromagnetic wave? Something else? That’s really what the OP is talking about. Don’t be shy! |
I think it’s an excellent question and actually a question that has a whole lot to do with the questions I’ve been asking on another thread: What is the audio signal in the system prior to the point where the speakers produce the acoustic waveform of the entire orchestra? AND how do better speaker cables, better power cords better fuses, vibration isolation affect the “audio signal,” whatever it is. |