A musical note has three characteristics.
- Quality (or tone)
- Pitch is a term used to describe how high or low a note a being played by a musical instrument or sung seems to be.
- The pitch of a note depends on the frequency of the source of the sound.
- Frequency is measured in Hertz (Hz), with one vibration per second being equal to one hertz (1 Hz).
- A high frequency produces a high pitched note and a low frequency produces a low pitched note.
- Loudness depends on the amplitude of the sound wave.
- The larger the amplitude the more energy the sound wave contains therefore the louder the sound.
- This is used to describe the quality of the waveform as it appears to the listener. Therefore the quality of a note depends upon the waveform.
- Two notes of the same pitch and loudness, played from different instruments do not sound the same because the waveforms are different and therefore differ in quality or tone.
The same note from different instruments has different qualities because the sounds from instruments are never pure notes, i.e. of one frequency, the only exception being a tuning fork. Rather they consist of one main note which is predominant and other smaller notes called overtones. The main note or fundamental note is also referred to as the first harmonic and if it has a frequency f, the overtone with frequency 2f is called the second harmonic and the overtone with frequency 3f is called the third harmonic and so on. The sum of all the harmonics is the waveform and determines the quality of the sound.