The Physics of Sound Pt 1



There are a myriad of pathways that one can take toward becoming a musician.  Some of us learn from family members, friends, books, instructional videos, listening to other musicians and so on.  Very often however we begin our journey with a teacher in or outside of an educational facility.  We are often initially taught the fundamentals of reading standard music notation and taught the techniques to recreate the tones and sounds that we see on paper without actually understanding what sound is and how it works.

According to the Encyclopedia Britanica, sound is; a mechanical disturbance from a state of equilibrium that propagates through an elastic material medium.  

Sound is defined by ANSI/ASA S1.1-2013 as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sensation evoked by the oscillation described in."

To expound upon this concept further; sound is a disturbance in air pressure; a vibration, energy.  For example, our vocal chords vibrate and cause a disturbance, change or fluctuation in air pressure.  The vibration in the form of a wave propagates from the source at a speed of 343.2 meters per second (1,126 ft/s; 1,236 km/h; 768 mph; 667 kn). Sound waves travel through the outer ear, are modulated by the middle ear, and are transmitted to the vestibulocochlear nerve in the inner ear. This nerve transmits information to the temporal lobe of the brain, where it is registered as sound.


The frequency of the sound is directly correlated to the speed of the vibration.  This vibration or frequency is measured in a unit of measurement called Hertz(Hz).  1 Hertz is one cycle or vibration per second.  A human being with optimal hearing can detect or hear sounds with frequencies between 20Hz to 20,000Hz (20kHz).  However due to hearing damage generally caused by exposure to loud sounds which is measured in decibels; after childhood adults can generally hear up to about 15kHz.

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The Physics of Sound Pt 2

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A musical note has two meanings.  The first definition is a reference to the pitched sound itself.  The second is a reference to a symbol in musical notion that defines the pitch and duration of a note.  The pitch is the quality of a sound governed by the rate of vibrations producing it.  The higher the frequency the higher the pitch; the lower the frequency the lower the pitch. The next major characteristic of sound is the timbre.  Timbre defines the unique tonal characteristics that distinguishes it from another. Timbre has four primary characteristics; attack, decay, sustain, release. The envelope of a sound has the following components and would look something like this: Attack - The time it takes for the note to reach the maximum level. Decay - The time it takes for the note to go from the maximum level to the sustain level  Sustain - The level while the note is held. Release - The time it takes for the note to fall from the susta...
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