The Physics of Music

Music is the creation of complex sequences of sounds that have a pleasent effect.

For some currently inexplicable reason, when more than one frequency is heard simulatanously, it can have an a profoundly pleasent or amazingly disconcerting effect.

In music, the sensation of frequency is commonly referred to as the pitch. A Low pitched sound vibrates at a lower frequency than a high pitched sound.

When two sounds are very close to the same pitch, we normally experience the sound as an oscillating sound with a beat. However, when the sounds differ enough, we start to hear the two separate, independent sounds. The degree of difference required is a major area of study in the field of psychoacoutics and is discussed in our section on psychoacoustics.

This affect is so powerful, musicians call the space between notes by a special name: the Interval. Lets look at the most common intervals used in music.

The Octave

The octave is simply the doubling of the frequency, or the creation of a sound with an interval ratio of 2 to 1. It sounds like this:

TODLK (sound - octave&&&)
The sound of an octave

The Fifth

The interval of a fifth is the most common and has a calming effect. It is obtained from the interval ratio of 3 to 2. This interval is created by simply taking a lower octave of the third harmonic. So, if we had a frequency of 100 Hz, the third harmonic is 300 Hz. One octave below 300 Hz is 150 Hz. So, the interval of the fifth would be created by playing a sound at 100 Hz and another at 150 Hz simultaneously. Note: It's easier to multiply the fundamental frequency by the ratio, 3/2 in this case, to obtain the second frequency.

The interval of the fifth sounds like this:

TODLK (sound - fifth&&&)
The sound of a fifth.

For more discussion on this subject, see musical intervals.

Law Of Octaves Different note, an octave apart, have the same tone.	Sound Harmonics Different vibration mode create harmonics.
Western Musical Chords Western musical chords are based on harmonics.	Musical Scales There is not just one musical scale. In fact, there are thousands.
Musical Intervals Find information about musical intervals along with a chart.	Musical Mathematical Terminology The savart and the cent are two mathematical music terms.
Music of the Spheres Johannes Kepler observed that the movements of the planets in relation to each other closely mimics musical intervals.	Fibonacci Sequence Leonardo Fibonacci observed what was later called the Fibonacci Sequence in the early 13th century.
Circle of Fifths Pythagoras discovered the Circle of Fifths more than 500 years BC.	Pythagorean Comma Although musical notes can be calculated mathematically, doing that creates notes which are slightly off pitch.

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