The Harmonic Series (BASIC)

What is the harmonic series?

 Right, basically the harmonic series is the over tones of a note played. When you play a note it does not only contain the one note but a set of overtones too. These are known as harmonics! Harmonics can be found in all pitched instruments (string, brass, woodwind, keyboard and some percussion). For now I’m going to be focusing on piano.

When you play a note, the first over tone you will hear will be an octave higher than the original note, after that will be the next 5^th followed by the next 4^th then the 3^rd. Notice there is a pattern going on here? All of these overtones are found in the original string and can be found because the string is vibrating differently through the whole string, the diagram below makes a bit more sense!

If I were to press C1 the harmonic series will be C2, G2, C3, E3. This will continue but each overtone will get quieter and quieter till it can’t be heard. 

There is a way of hearing this for yourself. If you press C2 on a piano gently so it makes no noise and hold it and strike C1, you can clearly hear the first over tone. Try this with the notes listed above or in the diagram and you should get a better understanding. Remember, all of these notes are all within the fundamental string. This exercise just amplifies it.

This video here will show you what I mean!

Waveforms (BASIC)

What do you mean by waveforms? 

Waveforms are the shape or the form of the signal played. Sounds that you hear in everyday life (e.g people talking, clicking fingers etc. basically anything that isn't artificial!) travel in sine waves; when you alter these waves you get a drastically different sounds. I will be looking at Sine, Square, Triangle and Sawtooth!

These waveforms look very different and produce different sounds and have different characteristics!

 

Sine waves: As I said in the beginning, sine waves are heard in everyday situations (Any sound which is naturally made and not put through a computer will be a sine wave). When we're talking about digital audio, this wave contains no harmonics, only the fundamental note! A sine wave is a true sound! You can tell if it's a sine wave because it's smooth and goes up and down like the ocean.

Square waves: This wave contains only odd harmonics (so the 1st, 3rd, 5th etc.). The harmonics are very dominant within this waveform! This gives it a buzzy hollow sound that is more noticeable at lower frequencies! Square waves are actually used to make artificial clarinet sounds. It's called a square wave for obvious reason (it looks like a square!).





Triangle waves: Triangle waves are very much like square waves because they only contain odd harmonics but unlike the square waves, the harmonics aren't very dominant because they're not as loud. To be honest they sound like a sine wave just with a little bit more added to it, not much. Some synthesizers favour triangle waves over sine because it has just that little bit more content. Again called the triangle wave for obvious reasons.... 




Sawtooth waves: A sawtooth wave is different to the others because it contains all of its harmonics. It is very distinctive to the others for its buzzing sound. This wave form is often used to create artificial bass, strings and some woodwind sounds.  The harmonics are natural sounding in a way because they are similar to what an acoustic instrument would be (Getting quieter in halves, then thirds then quarters etc.).  I don't even need to say say why it's called a sawtooth wave, I think you get the idea.

This example will let you hear the differences for yourself!