Sine wave:
a pure tone or fundamental frequency with no harmonics
or overtones.



Find out about Sine waves, Sine tones and Complex tones.

 

What is a Sine Wave?

This is a sound wave with a single frequency.  It produces a pure tone. It is a tone without harmonics or overtones.


If a single wave repeats or oscillates 100 times in a second then the wave has a frequency of 100 Hertz. The maximum height the wave reaches above and below zero is referred to as the amplitude of the waveform - how loud it is.

 

Why do choral conductors use
a tuning fork?

Because it produces a  pure tone or a sine tone with no harmonics. It is often used to give a clear pitch to a choral conductor because there is no other 'echo' getting in the way of the required note, so there is less of a risk of the singers picking up the wrong note.


Do you play the recorder? 

A descant recorder produces notes that are almost pure tones. It was replaced by the flute in the orchestra mainly because it was not loud enough.


 

Does all music consist of sine tones?

No. A sine tone has only the fundamental frequency with no other harmonics.
When you combine two or more sine tones you get a complex tone.
The blue, yellow and red waves below are sine tones.
When combined they produce the purple wave - a complex tone. Nearly all music consists of complex tones

 

 

  • Sit at a piano - not an electric keyboard.
  • Play the note C below the bass clef while holding down the right pedal. This takes all the dampers off the strings and allows other strings to vibrate.
  • You can faintly hear a C an octave higher than the C you played, as well as the G a fifth above that, the C above that, then the E above that... and so on. The C you played is called the fundamental. The notes you can faintly hear are its harmonics.

What are Harmonics?

Harmonics are frequencies that are multiples of a fundamental note.  Below you see the overtones we hear when the C (the fundamental) is played. Click on either stave to see and hear the first 16 overtones.



Leave the notation screen open on the computer.

On a piece of manuscript paper sketch in the harmonics of the bottom line G on the bass clef. The same pattern is observed ie. an octave, a fifth, a fourth a third and so on.

Write in 16 'notes' altogether.

The timbre or tone colour of a sound  depends on the relative loudness at any point in time of a series of harmonics, all of which can be thought of as sine waves. Any single sound is a kind of chord formed from harmonics.  The ear hears all the information as a single 'note'. 





... even-numbered harmonics (2nd, 4th, 6th) create an open, warm, filled-out sound.

... odd-numbered harmonics (3rd, 5th, 7th) produce a closed, harsh, stopped-down sound.

... the 2nd harmonic, an octave above the fundamental, might be barely audible, yet it adds fullness to sound.

... the 3rd harmonic softens the sound.

... harmonics above the 7th harmonic give the sound an edge or bite and definition.

Task 5
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