Reference Manual

CHAPTER 19. LIVE AUDIO EFFECT REFERENCE 268
19.21 Spectrum
The Spectrum Device.
Spectrum performs realtime frequency analysis of incoming audio signals. The results are
represented in a graph, with dB along the vertical axis and frequency/pitch along the
horizontal. Note that Spectrum is not an audio effect, but rather a measurement tool - it
does not alter the incoming signal in any way.
The Block chooser selects the number of samples that will be analyzed in each measurement.
Higher values result in better accuracy, but at the expense of increased CPU load.
Channel determines which channel is analyzed - left, right or both.
The Refresh slider determines how often Spectrum should perform an analysis. As with the
Block parameter, this allows for a tradeoff between accuracy and CPU load. A fast response
time is more accurate, but also more CPU intensive.
The Avg slider allows you to specify how many blocks of samples will be averaged for each
update of the display. With a setting of one, each block is shown. This results in much more
activity in the display, which can be useful for nding the spectrum of short peaks. As you
increase the Avg value, the display updates more smoothly, providing an average of the
spectrum over time. This is more consistent with the way we actually hear.
The Graph button switches between displaying the spectrum as a single interpolated line
and discrete frequency bins.
The Scale X buttons allow you to toggle the scaling of the frequency display between
linear, logarithmic, and semitone. Note that logarithmic and semitone are actually the same