Apple Final Cut Express 4 - Manual (Page 659)

Chapter 44 Using Audio Filters 659
VIII
Unlike a compressor, which affects the loud parts of a signal, expansion affects the
quiet parts of the signal:
 Threshold: This slider defines how low the lowest portion of the clip can be before
expansion is applied. This is the first setting you’ll adjust.
 Ratio: This slider affects how much expansion is applied to boost the signal.
 Attack Time: This slider defines how quickly the filter reacts to changes in audio level
(the default is usually fine, but you may want to experiment).
 Release Time: This slider defines how slowly the filter lets go of the change in audio
level it made (the default is usually fine, but you may want to experiment).
Noise Reduction Filters
Final Cut Express has three noise reduction filters for use in specific situations:
 Hum Remover
 Vocal DeEsser
 Vocal DePopper
Hum Remover
The Hum Remover lets you get rid of “cycle hum” that may have been introduced into
your audio recording by power lines crossing your cables or by a shorted ground wire
in your setup. Hum from power sources generally sounds like a low buzzing and has a
frequency that corresponds to the electrical power in your country (for example,
countries in North America use 60 Hz AC power, whereas most countries in Europe
use 50 Hz power).
 Frequency: This slider lets you select the frequency of hum that this filter will attempt
to remove. Different countries use different power frequencies, so you need to
specify exactly what frequency to tune out. In general, most AC (alternating current)
operates at either 50 or 60 Hz.
 Q: This slider adjusts the filter resonance around the value of the Frequency slider.
Higher Q values result in a narrower but stronger resonance, which limits the
frequencies affected by the filter. If the important elements of your recording overlap
into the frequencies that are being filtered out, you might want to narrow the range
of frequencies affected.