Apple Soundtrack Pro 3 - Manual (Page 279)

• Predelay time: In an acoustic space, there is a short period of silence between a sound
and the time when the initial echoes of the reverb begin. Different spaces have different
amounts of predelay, which helps “tell” our ears how large the space is. Longer predelay
settings also help separate the original (dry) signal from the effected (wet) signal, making
it sound clearer and sometimes larger.
• Early reflections: The first echoes to arrive from the surrounding surfaces in a space are
determined by the size and shape of the space, and “tell” our ears what type of space
it is.
• Diffusion: Lets you set the number of the echoes in the reverb. Hall reverbs typically
have low diffusion settings, while plate reverbs typically have high diffusion settings.
• High-frequency and low-frequency reverb time: These parameters let you specify the
decay of higher and lower frequencies separately. Different surfaces, such as wood
floors and concrete walls, absorb high and low frequencies at different rates, and these
parameters let you simulate the sound of different environments more closely.
• Reverb envelope: Lets you control how much the volume of the reverb changes over
time. In natural acoustic situations, the reverb echoes decay gradually over time. You
can re-create this gradual decay, or gate the reverb so that it cuts off more abruptly.
Meters and Diagnostic Effects
Diagnostic effects help you analyze and clean up audio in a variety of ways. Each type of
diagnostic effect provides a different way to “look at” an audio clip or file, and each has
a unique set of parameters. These effects are available only as realtime effects in the
Effects tab and the Mixer, not as processing effects.
Correlation Meter
The Correlation meter displays the phase relationship of a stereo signal. A correlation of
+1 (plus one, the far right position) means that the left and right channels “correlate”
100% (that is, they are completely in phase). A correlation of 0 (zero, the center position)
indicates the widest permissible left/right divergence, often audible as an extremely wide
stereo effect. Correlation values less than zero indicate that out-of-phase material is
present, which can lead to phase cancelations if the stereo signal is combined into a
monaural signal.
MultiMeter
The MultiMeter combines the functions of the Level Meter and Correlation Meter (as
described above) with several other analysis tools:
• A Spectrum Analyzer
• A Goniometer for judging the phase coherency in the stereo sound field
279 Chapter 10 Working with Audio Effects