Sounds - Musical Notes

Timbre - Tone of Sound


The sounds are longitudinal waves that propagate through a propagation medium. The notes are sounds at fixed frequencies (fundamental), which when combined properly leave to human ear a pleasant auditory sense.


Author: Dimitrios Porlidas

Curriculum Vitae






The sound is a longitudinal wave, namely the shift of the airwave is in the direction of propagation of the wave. In the air the sound spreads from the vibration and the oscillation of the molecules of air. From a source that oscillates some air molecules generate periodic pressure differences, which spread through the environment, creating sound waves. The human ear responds to these pressure differences.

The notes are sounds at fixed frequencies (fundamental), which when combined properly leave to human ear a pleasant auditory sense. The musical notes are classified in octaves, which are repeated. Two successive octaves include the same notes at twice their fundamental frequencies. In an octave distinguish seven different notes. The nomenclature has prevailed globally assigns the first seven letters of the Latin alphabet in seven basic notes: A, B, C, D, E, F, G. At the same time is used the Latin nomenclature too which is respectively: la, si, do, re, mi, fa, sol. Furthermore, mostly used a number in the name of the note, which indicates in which octave the note belongs. Among some of the seven basic notes exists some more notes, identified as the hash key and designated by adding the # symbol in the name of the basic note. The series of notes finally formed by the following steps: A, A #, B, C, C #, D, D #, E, F, F #, G, G #. The change from one step to another is called semitone, while two successive semitones constitute a tone. The relationship between the fundamental frequencies of two consecutive semitones given by the expression:

As a characteristic note, the basis of regulating most musical instrument is the A4 with frequency 440Hz. The figure below shows the diagram of the notes used in music. The horizontal axis shows the notes and the vertical axis the frequency in logarithmic scale.

When a note is produced by any musical instrument, the resulting sound wave contains the fundamental frequency and also multiples of it called harmonics. Each instrument has its own characteristic sound, so we can distinguish it from other instruments and recognize it. This feature is called timbre or tone of the instrument and depends on the harmonics the instrument can produce and the intensity of each shaping in the final sound. So it is possible to determine the frequency spectrum for each instrument and reflected in the chart. The figure below shows the frequency spectrum of the violin which distinguished the first ten harmonics. The first harmonic (1) is the fundamental frequency and the remaining harmonics (2-10) is derived first to ninth frequencies (overtones 1st to 9th).



© 2014 Dimitrios Porlidas