How can we hear more than one frequency?

Question

I don't understand how speakers can produce and how we can hear more than one sound or frequency at a time.

Answer 1

A tuning fork playing A above middle C vibrates 440 times per second. That sound will resonate with one specific part of your ear, regardless of the presence of other sounds. At each point in time, the air pressure at the microphone will be the linear superposition of the air pressure from all the sound waves from all sources of all frequencies. The speaker reproduces that linear superposition, so your ear couldn't tell the difference between the sound from the speaker and the sound at the microphone.

A different part of your ear responds to middle C. You hear both because both sensors are activated. In the same way, you can feel pressure on your left hand and on your right hand at the same time.

Answer 2

Speakers vibrate, but the vibration is not a single frequency and the wave produced is not a pure sine wave but the combination of all the frequencies.
Our ears have different specialized sensor cells for high and low frequencies. Our brain does the rest.

Answer 3

i dont know how speakers produce more than one but i know how we hear more than one. we have a lot of hairs in our inner ear that when stimulated cause us to sense sound. these hairs can all be stimulated individually even several at the same time depending on whats entering the ear drum.