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Monitoring
Audio monitoring
Audio scopes
FFT Spectrum Analyzer

FFT Spectrum Analyzer

The FFT spectrum analyzer, labeled FFT Spectrum in CineMon, uses a fast Fourier transform (FFT) to plot signal level by frequency as a continuous curve. Low frequencies appear on the left and high frequencies on the right; height indicates signal level. Choose an open curve or a filled shape. For a bar display, see the Band Spectrum Analyzer.

FFT Spectrum Analyzer with a filled spectrum and an Instant Peaks curve
A filled spectrum with the Instant Peaks curve overlaid.

Two controls smooth the curve:

  • Spectral smoothing averages neighboring frequencies, reducing narrow spikes. Choose an octave fraction from a broad 1 Oct down to a detailed 1/12 Oct.
  • Temporal averaging averages readings over time, from Off to Very Slow. More averaging reduces moment-to-moment changes in the curve.

You can also overlay an instant peaks curve that ignores temporal averaging, so the fast peaks stay visible on top of the smoothed curve. As with the Band Spectrum analyzer, a decay rate sets how quickly the curve and the peaks overlay fall back.

Basic use

Open Scopes in the status toolbar and select FFT Spectrum. If the menu is hidden in a narrow window, open More Controls (…).

Use the scope’s settings button to adjust the options described below.

  1. Select the channel and choose a curve or filled display.
  2. Adjust Spectral Smoothing for frequency detail and Temporal Averaging for how quickly the curve responds.

Options

SettingOptionsDescription
Render StyleCurve / FilledDraw an open curve or a filled shape.
Spectral SmoothingOn / OffAverage neighboring frequencies for a cleaner curve.
Octave Fraction1 Oct / 1/2 Oct / 1/3 Oct / 1/6 Oct / 1/12 OctHow much spectral smoothing to apply. Shown when smoothing is on.
Temporal AveragingOff / Very Fast / Fast / Medium / Slow / Very SlowSmooth the curve over time.
Instant PeaksOn / OffOverlay the fast peaks curve, unaffected by temporal averaging.
Window FunctionHann / Blackman-HarrisThe FFT analysis window.
ChannelL/R Average / L/R Max / Left / RightWhich channels feed the analysis.
Slope CorrectionNone / 3 dB/Oct / 4.5 dB/OctTilt the curve to match a chosen reference slope.
Decay Rate4 to 50 dB/sHow quickly the curve falls back after a peak. Default is 11.8 dB/s.
Floor-60 dB / -90 dBThe bottom of the display scale.

The FFT Spectrum analyzer is available with the CineMon PRO Audio Monitoring Pack or a CineMon PRO Pass subscription.

Related topics

Band Spectrum Analyzer