Applying Properties of Loudness in Music=Dynamics

Degrees of loudness and softness in music are called dynamics.

Loudness is related to the amplitude of the vibration that produces the sound.
 
An accent is playing a note more loudly than the notes or tones around it.

Dynamics are traditionally notated using Italian words and their abbreviations.
Digital Audio (Sound) As Related To Dynamics
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Listening Guide

Excerpt from Stravinsky's The Firebird, Scene 2
1. Begins with slow melody in French horn, soft (p).
2. Violins are soft with the melody and octave higher.  Flutes join in.
3. Music grows louder (crescendo) as additional instruments enter.
4. Crescendo continues to full orchestra with melody very loud (ff), timpani is added.
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