Amplitude is associated with the height of a sound wave and is related
to volume.When a stereo, amp, or television’s volume is turned up or down,
the amplitude of the sound being projected is increased or decreased.
Loud sounds have higher amplitudes while quiet sounds have lower amplitudes.
The greater the amplitude of a sound the greater the sound pressure
level.Amplitude is measured in decibels (dB).
Most people can recognize about a 3 dB change in amplitude. A trained ear
can recognize even smaller amplitude changes.
An increase in amplitude is usually expressed as a “boost” and a decrease
in amplitude is often expressed as a “cut.”
The word volume is often substituted for amplitude.
An audio engineer may say, “boost that 3 dB” or “cut that 3 dB.” When
amplitude is written out,
it is expressed with a positive sign such as +3 dB or a negative sign such
as −3 dB.Here are some common activities and their corresponding decibel
levels: 0 dB – near silence 40–50 dB – room ambience 50–60 dB – whisper
60–75 dB – typical conversation 80–85 dB – a blender, optimum level to
monitor sound according to the Fletcher–Munson curve 90 dB – factory noise, regular exposure
can cause hearing damage 100 dB – baby crying 110 dB – leaf blower, car
horn 120 dB – threshold of pain,
can cause hearing damage 140 dB – snare drum played hard from about 1′
150–160 dB – jet engineAs you can see, in our daily lives,
we are constantly confronted with amplitude levels between 0 dB and about 160 dB.
Most people listen to music between 70 dB (on the quiet side) and 100 dB
(on the loud side). Appendix A covers dBs in more detail.