PreSonus StudioLive 24.4.2 - Manual (Page 36)

3 Universal Control and VSL
3.6 VSL: GEQ Tab
StudioLive ™ Software Library
Reference Manual
32
Many audio signals that are encountered in the field are highly dynamic. Musical
signals, speech, and even environmental noise contain significant changes in spectral
content as a function of time. The Spectrograph can be thought of as a record of
multiple RTA measurements taken over time, with color representing amplitude.
Using this function, the spectral content of the input signal is recorded as it changes
in time. This allows you to view and analyze time-varying trends in the input signal.
As a troubleshooting tool, the Spectrograph is useful for finding spectral “defects”
in a system or acoustical environment. Certain audio signals or acoustical events
contain specific traits that can be easily detected due to their distinct time/
frequency signature—specifically, highly tonal sounds such as AC line noise
in an electrical signal chain or the presence of electro-acoustical feedback.
Dynamic Range
In the lower left-hand corner, you will see the dynamic-range sliders for the
Spectrograph. These sliders set the maximum and minimum volume thresholds for
the Spectrograph.
3.6.6 RTA
Clicking on the RTA button will launch the Real-Time Analyzer where x = frequency
and y = amplitude. An RTA provides a close visual representation of what you are
hearing. It provides a view of the long-term spectrum of the signal—for example,
the one-third-octave spectrum long-term average of a musical performance.
Averaging
While the RTA is engaged, you can adjust its averaging speed. When using music in
test measurements, it is often necessary to average the data over a brief amount of
time. This is because most musical signals do not have energy at all frequencies all of
the time.
Averaging is a mathematical process that takes multiple data samples and performs
division to acquire a statistically more accurate calculation of the response. That’s a
technical way of saying that it slows down the “real-time” of a Real-Time Analyzer.