Apple Final Cut Express 4 - Manual (Page 604)

604 Part VIII Audio Mixing
The most important distinction is the difference between an audio clip’s peaks and its
average loudness:
 Peaks are short, loud bursts of sound. In spoken dialogue, letters like P, T, and K at
the beginning of words can result in peaks if the person speaking is close to the
microphone. In music, peaks occur at the very beginning of sounds from percussive
instruments such as drums.
 The average loudness of a clip generally determines its overall perceived volume, and
this is probably somewhat lower than the level of the peaks. In the sample waveform,
the level of average loudness appears as the densest, darkest part around the middle.
Average loudness, rather than the brief peaks, tends to influence your decision about
mixing a sound higher or lower.
Analog Versus Digital Meters
The way you set your levels with a digital meter is different from the way you set levels on
an analog meter. Compare a traditional analog audio meter with a digital audio meter:
A digital meter displays the sample values of a digital audio signal. The scale on the
meter is known as digital full scale, and the signal is measured in dBFS. On this scale,
0 dBFS represents the highest-possible sample value. Any samples above 0 dBFS are
clipped, distorting the original shape of the audio waveform. Once a signal is clipped,
the original shape of the waveform cannot be recovered.
Generic
VU meter
Final Cut Express
audio meters
-30
-20
-10
-7
-4
-2
0
+2
+4
+7
- ∞
-66
-36
-24
-18
-12
-6
0
-48