Record Label 101

Harmonics and Waveform – Part 2

 Harmonics Track
When a string vibrates, as on a piano, it actually vibrates in many different places.

Below is a picture of all the different vibrations on a bowed string. Each different frequency is heard as a harmonic. If you press lightly on a node while strumming or plucking the string, you will hear the harmonic instead of the fundamental (actually, the harmonic became the fundamental, that’s why you hear it instead of the original fundamental). This is how guitarists tune their guitars with harmonics. It’s easier to hear if it’s in tune because the notes are higher in pitch.

The fundamental and all its harmonics are also called the “overtone series” and are notated as follows:

When you play that lowest C, you are actually hearing all those other notes as well. Additionally, because of a combination of physics and musical insight,  instruments are designed to play the first seven or eight harmonics with one fingering.

Waveform

Different waveforms are created by adding and subtracting certain harmonics.
The sine wave is a pure sound and emphasizes the fundamental.  The square wave emphasizes odd numbered harmonics. The triangle waveform emphasizes very few specific odd numbered harmonics. The sawtooth wave emphasizes all the harmonics.

Click below to hear examples of each of these types of waves:
Sine, Square, Triangle, Sawtooth

Another synth principal is the envelope of the sound. The start, middle, and stop of the sound is what makes it sound different over time. This envelope is called:

Attack, Decay, Sustain, Release

an example of an ADSR Envelope. This could be a very stilted piano sound.

Now all these videos on Teachertube…


Introduction to Harmonics

Tuning Fork and Piano

Breaking the Sound Barrier

Piano Harmonics

Bowing across the string in slow motion

Introduction to Sound Waves (1950s video)