So from what I know, the drivers vibrate at a given wavelength and that makes a sound. That makes sense to me of how you can create voice for example. But how does multiple instruments + voice in one driver work? You hear all them seperately but at the same time?
To me this sounds like a monitor pixel making more than 1 pixel at once.
In: 135
Drivers don’t vibrate at only one wavelength. All drivers are doing what they can to create pressure waves in the air according to the signals they’re receiving.
Low-frequency sounds need the diaphragm to move a greater distance for the sound to be heard, which requires that the mass of the driver be greater. The human ear isn’t super sensitive to low-frequency sounds, so the amount of energy that needs to go in to reproducing the waves goes up. For these reasons, we normally use subwoofers for low-frequency sounds.
Tweeters have the opposite problem. They need to move very quickly, and only a very short distance in order for the sound to be heard. This also means we need considerably less energy to do it.
While you can drive a subwoofer with high-frequency sounds, the diaphragm simply *can’t physically move* that fast with the available energy, and so the high-frequency sounds don’t really make it out. Similarly, you can drive a tweeter with low-frequency sounds, but the diaphragm isn’t going to move very far with each wave, and the resulting pressure wave won’t be heard.
The sound “wave” that is produced by a driver, either way, is going to be a mixture of all of the sound waves being reproduced. Imagine throwing a stone into a calm lake, and watch the one pure wave move outward from where it was created. But throw many stones, and pick a random point on the lake’s surface, and that point will be moving up and down in a complex way that isn’t always obviously tied to the different waves that make up its motion.
In the digital signal processing world, we think of sound waves as a composition of many different pure sine waves, with each sine wave frequency having its own “volume” or contribution to the total. There is an algorithm called the Fourier transform that we can use to take that total waveform and separate it into its basic components, just like a prism takes a beam of white light and separates out the different colors.
The human ear does something very similar. The cochlea has a spiral shape, so that sound vibrations of different frequencies fit further into the spiral, and end up tickling tiny hairs at each point. High frequencies get deeper into the cochlea before their energy ends up vibrating the hairs, and we perceive that distance as a higher frequency of sound. This lets us “un-mix” the sounds into their component sine waves similar to how the Fourier transform works. We can then use that separated signal to match against patterns of human speech to understand what someone is saying, even though the waves that make up that speech might be generated by a combination of multiple types of speaker drivers reproducing a signal that was captured by an entirely different microphone that itself is just a diaphragm vibrating an “inverse” driver, capturing all of the original waves from the original spoken words.
I’ve explained this one before a few times, e.g. [here](https://www.reddit.com/r/explainlikeimfive/comments/o2kwbj/Eli5_how_exactly_speakers_recreate_let’s_say_a_human_voice._I’m_not_talking_about_analog_or_digital_conversion,_i_know_a_bit_about_those_subjects._But_the_physical_act_of_a_speaker_cone_moving_back_and_forth,_perfectly_recreating_a_human_voice_or_any_other_kind_of_recording_seems_like_magic_to_me/h274zz6/?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=2). But the really short version is that headphones are just trying to make your eardrums vibrate in a certain way to make you experience things as if you were listening to the actual thing.
You’ve only got one eardrum per ear, so you only need one driver per ear!
The clever part isn’t done by your headphones, but by your brain.
You can add multiple pitches together to make a more complicated wave. We can use maths to split these different pitches back out, but mechanisms in our ears actually do that physically, meaning each different pitch gets sent along a different nerve bundle from our ears to our brains. Our brains then add things together based off patterns we know, and figure out what all the different sounds are meant to be.
imagine the air being the surface of a pond. toss one pebble into the pond, you get a single wave radiating from the source. if you are standing in the pond the wave will hit your leg at some point. or a leaf floating in the pond would move up and down with the wave, same as how your ear drum moves when a sound pressure wave gets to it.
now toss two rocks in, one after another, the second one landing in a different spot. what you see now on the water is a pair of waves, with them crashing into each other and interfering. when the waves are both up at the same time, the water is higher at that point. same when they’re both lower. when on wave is up and the other slightly down, the water will be somewhere in between. your leaf will move with the wave combination just like your ears will hear the sound combination.
a speaker can play back multiple waves stacked on top of each other, just like the leaf movement is two or more waves pushing it up and down.
Superposition.
Remember that scary sounding word from quantum mechanics? Well, it’s not really that scary. Waves can add up to form a “super wave” that is really just the same as multiple different waves at the same time.
It’s just like how a chord is just two or more notes played at the same time.
And that’s precisely how our ears experience sound. The drum can only report one frequency at a time. What you’re hearing is a superposition of all the individual waves.
The reverse question is: how are your ears able to perceive more than one sound at the time? It is also a singular diaphragm, the ear drum, vibrating, but yet somehow it accomplishes the feat. Answer: it is fundamental property of sound that they can be summed together and both generated and perceived at once.
I think you might be confusing an object’s natural vibration modes with a *driven* loudspeaker. The natural one(s) are due to physics and elasticity, etc.
But a driven loudspeaker is moving in response to the electrical signal being fed to it. Feed a simple high frequency sound and it will vibrate fast. Low, also low. Feeding it a complex audio signal makes it vibrate in a way that replicates the sounds that created that audio signal.
How your ear and brain perceive sound based on the vibrations of your ear is a separate question, but it doesn’t sound like you have confusion of how you can hear multiple things directly.
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