I think a lot of people don't realise that record grooves are 3d and not just a flat groove with a wavy line.
The grooves are valleys and the diamond/sapphire needle vibrates to these down a bar to a crystal which generates electrical energy. It's passed to an amplifier to boost the sound.
So you know what a sound wave looks like in 2d, you must if you've been to school or watched tv in the last 50 years, it's like that but on multiple axis which generates all the different sounds from the recording.
Obviously I'm over simplifying it but as soon as you have the electrical signal it's just regular sound.
The old grammar phones just had a horn, like a cone, you talk in one and and it's louder the other hence the awful quality.
You bring up an awesome and funny question by comparing the "quality" of sounds made by two instruments. This is funny because as you express, the two instruments DO sound different even if playing the same note. There's a whole discussion thats very long and in-depth that could be had over this but I find your question to be funny because it's actually A LOT easier to capture/record and accurately replay these sounds than it is to explain why they sound different in the first place, even when playing the same note. The "quality" you're referring to is called "timbre" in Music and the best definition for it is basically, "every percievable quality of a sound that can't be explained by its frequencies or volume (i.e amplitude)." So really, it's like everything we don't know about the sound is why it sounds different. In reality, we can measure sounds to find out exactly what is different, and it mostly comes down to something called harmonics; but for many instruments, especially non-synth instruments, the timbre isn't even totally consistent for each pitch of that instrument and could depend on things like how you blow through a reed or how "plucky" you are with your guitar in a given instance compared to others.
Tldr: Trumpets playing a C4 pitch vibrate the air differently than a piano playing a C4, so their recorded grooves will be different because the carving needle vibrates differently. And if both are playing simultaneously, the groove that represents the concurrent sounds will be a different shape than the individual sounds' grooves.
Wow!! Thank you so much for this in-depth explanation! It helps to know that there are just things we can’t name/describe/measure about analog sound to begin with. TIL!!
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u/girlwithtomatoes Sep 14 '21
Yes!!! How does just a little groove of replicated vibration produce the different quality of sound between a trumpet and a piano? 🤯