Brief intro to soud.

hmm...

All sound come out of vibration of a material, and it travels through air. So, you can't hear any sound in vacuum.

When a material vibrates, it has its vibration rate. This is proportional to the frequency. Human only listen to frequency from 35Hz to 20kHz.

35Hz is something very bassy, 20kHz is very high pitch. So, it's actually inaudible for older people. We human is very sensitive to sound around 1kHz, our speaking voice is approximately in those range as well.

Everything vibrates, but they don’t produce the same sound. Every material has its own characteristic on the vibration they produce and its effects on air. For example, you tie a string on a material, and apply some tension on it. Tension makes sure that you won’t get anything too bass till inaudible, since at least we need 60 cycles per second of vibrations. If you tie it to

a glass, it may sound ‘glassy’. Tie it on a wood, you may find it ‘woody’. And, tie it on a table and it’ll become louder (because table has a depth, just like the different sounds produced by an acoustic guitar and an electric guitar.

So, take guitar as an example. The sound come out of it depends not only on its wood. It depends also on its inner brace and dimensions design. Yet, wood

really affect much of the tonal quality. However, some guitar manufacturers, such as the Ovation USA, are using the helicopter blade material to replace the wood of the guitar’s body. Also, if Taylor and Martin both using the same grade’s wood to build a guitar, it won’t sound the same, because the design each of them using are so different. If considering the string? But the main point here is that all these sounds very different form the plain pure sine wave.

This is what we call musical instrument.

This can be imagined as few waves, each with its own frequency and amplitude (loudness) all blended up together. And this will give out something very special. For any two instruments, they’ll sound maybe very different or slightly different. Again, this is caused by the dimension of the ‘guitar sound box-its inner resonance’, the strings used and the wood. There are many other factors as well.

Same thing applies to speakers. But for speaker, it’s much more difficult to design (I think so), because it has to be able to reproduce full range frequencies.

Just a share of knowledge! Found these online.