Apple Soundtrack Pro 2 - Manual (Page 465)

Appendix B Audio Fundamentals 465
Frequency Spectrum of Sounds
With the exception of pure sine waves, sounds are made up of many different
frequency components vibrating at the same time. The particular characteristics of a
sound are the result of the unique combination of frequencies it contains.
Sounds contain energy in different frequency ranges, or bands. If a sound has a lot of
low-frequency energy, it has a lot of bass. The 250–4000 Hz frequency band, where
humans hear best, is described as midrange. High-frequency energy beyond the
midrange is called treble, and this adds crispness or brilliance to a sound. The graph
below shows how the sounds of different musical instruments fall within particular
frequency bands.
Note: Different manufacturers and mixing engineers define the ranges of these
frequency bands differently, so the numbers described above are approximate.
∏
Tip: The human voice produces sounds that are mostly in the 250–4000 Hz range,
which likely explains why people’s ears are also the most sensitive to this range. If the
dialogue in your movie is harder to hear when you add music and sound effects, try
reducing the midrange frequencies of the nondialogue tracks using an equalizer filter.
Reducing the midrange creates a “sonic space” in which the dialogue can be heard
more easily.
Time
Bass
Mi
d
High
Cymbal crash
20 Hz
300 Hz
4 kHz
20 kHz
Violin and flute
Cello
Bass line
F
requenc
y