The Spectral Analysis tool in Sound Forge Pro is under View → Spectrum Analysis. It opens a frequency-domain view of whatever audio you have selected — amplitude on the vertical axis, frequency on the horizontal. FFT size, display mode, real-time monitoring, snapshot storage — all of it lives in that window. It's not a spectral editor; it doesn't let you paint out frequencies. It's a measurement and diagnostic tool, and knowing how to read it changes how you use EQ.
Part of the Sound Forge restoration hub. New to the editor? Start with the complete Sound Forge 2026 guide.
Quick answer: View → Spectrum Analysis → select audio → click Refresh (or enable Auto Refresh). For real-time monitoring during playback, click the Real-Time Monitoring button. The rest explains what the settings actually do and when each display mode is useful.
Spectrum Analysis, Spectroscope, WaveColor — Which Does What
Sound Forge Pro has three frequency visualization tools and people routinely mix them up.
Spectrum Analysis (View → Spectrum Analysis) — the full FFT analysis window. Shows frequency content of a selection as a static or refreshed graph. Has FFT size controls, sonogram mode, snapshot storage. Primarily for diagnostic analysis: finding problem frequencies, comparing before/after EQ, identifying noise profiles.
Spectroscope — the real-time frequency meter, accessible via the Channel Meters panel (View → Channel Meters, then right-click the meters area). Shows frequency content continuously during playback. No snapshot, no settings depth. Useful for monitoring while applying effects and hearing what changes in real time.
WaveColor — not a separate window. It colors the waveform display itself: low frequencies show as one color, mids another, highs another. A quick visual scan before you open any analysis tool. No numeric values, no scale.
Use the three views in sequence instead of treating them as substitutes. WaveColor is the fast scan across the whole waveform, Spectroscope is the live frequency meter, and Spectrum Analysis is the precise view for cursor readouts, FFT settings, sonograms, and before-and-after snapshots.
Opening Spectrum Analysis and Basic Navigation
Go to View → Spectrum Analysis. The window docks into the Sound Forge interface or floats — drag the title bar to position it. It doesn't update automatically until you tell it to.
Select a region in your audio file, then click Refresh in the Spectrum Analysis toolbar. The graph updates to show the FFT of your selection. If no selection exists, it analyzes from the cursor position forward. Enable Auto Refresh (the button with the circular arrow) and the display updates every time you change your selection — useful when you're hunting for something specific and moving through the file quickly.
Hover the cursor over any point in the spectrum graph. A tooltip shows the exact frequency and amplitude at that position. Right-click and enable Show Position to keep it visible. Right-click and enable Show Notes to display the nearest musical note — useful when you're analyzing a recording and need to identify a resonant peak in terms of pitch rather than Hz.
FFT Size: The Setting That Determines What You Can See
Click the Settings button in the Spectrum Analysis window. FFT Size is the first control worth understanding — everything else in the dialog is secondary to it.
FFT size determines frequency resolution — how narrow the analysis bands are. Larger FFT size = better frequency resolution = longer computation time. Smaller = faster update, coarser frequency view.
Start with 4096 or 8192 for general diagnosis, then increase the size only when you need to separate close frequencies or read hum harmonics more precisely. At 44.1 kHz, approximate FFT-bin spacing is sample rate divided by FFT size: 10.8 Hz at 4096, 5.4 Hz at 8192, and 2.7 Hz at 16384. The current Spectrum Settings documentation confirms the trade-off: a larger FFT improves frequency resolution but reduces time resolution and takes longer to calculate.
| FFT size | Bin spacing at 44.1 kHz | Useful starting job |
|---|---|---|
| 2,048 | 21.5 Hz | Responsive real-time overview |
| 4,096 | 10.8 Hz | General tonal diagnosis |
| 8,192 | 5.4 Hz | EQ and resonance checks |
| 16,384 | 2.7 Hz | Narrow hum harmonics |
Approximate spacing = sample rate ÷ FFT size. A smaller bin is not automatically a better decision: it also represents a longer time window.
Smoothing Window changes peak sharpness and leakage into neighboring frequencies. The 2026 help describes Blackman-Harris as the option with the least sideband leakage, at the cost of rounded peaks; Rectangle produces a sharper peak but much higher leakage, while Hamming and Hanning are common audio choices. Blackman-Harris is a sensible diagnostic starting point, but the curve is still an analysis view, not a literal instruction to EQ every visible peak.
Don’t notch a frequency only because it looks tall. Loop the same short passage, move the cursor over the peak, listen for the problem, then capture a snapshot and test a small EQ move. If the change is not clearly better in Bypass comparison, restore the EQ even when the graph looks flatter.
Display Modes: Graph Types and Logarithmic Scale
Right-click the graph for display options.
Line Graph is the default and fastest — clean frequency curve, low CPU. Filled Graph fills the area under the curve, easier to read at a glance but slower on some systems. Bar Graph shows frequency as discrete vertical bars — good for visualizing broad frequency regions but loses detail on narrow peaks. If the display feels sluggish, switch to Line Graph first.
Right-click and enable Logarithmic to toggle the X-axis between linear and log scale. Log mode devotes more horizontal space to lower frequencies and is usually easier for broad audio diagnosis. Linear mode is useful when you want equal spacing for equal differences in hertz. This setting changes only the display, not the audio or the underlying FFT data.
Right-click and choose Normalize dB to scale the Y-axis to the actual range of your audio — useful when you're looking at a quiet recording and the peaks are buried in the bottom third of a -100 dB to 0 dB scale. Normalizing the display brings the content into the visible range without affecting the file.
Snapshots: The Feature Most People Skip
The current graph documentation says Spectrum Analysis can store up to four snapshots from one or several data windows. Snapshots can be overlaid for a direct comparison, but they are unavailable in Sonogram display and when Slices displayed is greater than 1. Set both analyses to the same selection, FFT size, window, channel, and display range before judging a difference.
Click Set in the toolbar, then click one of the four snapshot buttons (labeled 1–4). The current graph is stored. Apply an EQ or other process, refresh the analysis, and the snapshot from before remains visible alongside the new result. You can compare four different states at once.
Snapshot before NR, run noise reduction, refresh and compare — see exactly how much the noise floor moved and whether you introduced any spectral artifacts. Snapshot before EQ, apply a cut, compare. Snapshot a reference track, then analyze your own mix in the same window — see where they diverge.
To hide individual snapshots without deleting them, click the snapshot button again to toggle it off. Click Clear All Snapshots to wipe them. You don't need to erase to overwrite — just click Set and then the snapshot button to replace it.
The Sonogram: Time and Frequency Together
Click the Sonogram button in the Spectrum Analysis window to switch from the standard spectrum graph to sonogram view. The axes change: time runs left to right on the X-axis, frequency runs bottom to top on the Y-axis, and amplitude is shown as color intensity. Brighter or more saturated = louder at that frequency at that moment in time.
The sonogram makes time-varying frequency content visible in a way the standard spectrum graph can't. A 60 Hz hum that's constant shows as a continuous horizontal line at the bottom. An intermittent click appears as a vertical flash across all frequencies. Tape hiss appears as a constant mid-to-high frequency band. A resonance that only appears during certain passages shows as a bright horizontal stripe that turns on and off.
FFT size still applies in Sonogram mode: higher values improve frequency resolution while taking longer to render. Start at 2048 or 4096, then raise it only when close frequencies need separation. The current Sonogram documentation recommends increasing Set sonogram resolution to about 200 when the view looks chunky and narrowing frequency and amplitude ranges to create clearer contrast.
Color or black-and-white: both available via right-click on the sonogram. Color mode makes amplitude differences more visible at a glance; B&W works better for printing or when you're screenshotting for documentation.
Real-Time Monitoring
Click the Real-Time Monitoring button and Sound Forge continuously updates the Spectrum Analysis display during playback. The dropdown under that button lets you choose between monitoring the input signal (useful when recording) or the output signal (useful when monitoring effects during playback through the Plug-In Chainer).
Real-time monitoring requires processing power. If the display refresh becomes sluggish, the current 2026 help recommends switching to Line Graph, decreasing FFT size, or turning off snapshots. Change one setting at a time so you know what restored a stable refresh; use static Refresh instead of real-time monitoring when the machine still cannot update cleanly during playback.
Monitoring output through the Plug-In Chainer is useful during mastering: load your EQ chain, start playback, watch the spectrum update in real time, adjust the EQ while hearing and seeing the result simultaneously. This is the workflow the Spectroscope handles too, but Spectrum Analysis gives you more control over the display and the ability to snapshot a state for comparison.
What Spectrum Analysis Won't Do
Spectrum Analysis is a viewer, not an editor. It can identify a peak or time-varying noise, but it cannot paint that frequency out. For spectral editing, the current Sound Forge 2026 integration help documents an ARA workflow with a compatible SpectraLayers VST3 installation. That application must be installed and licensed separately: the current Sound Forge pricing page does not list SpectraLayers as included with Sound Forge or Sound Forge Plus. iZotope RX is also a separate product. The noise-reduction guide covers what Sound Forge's own broadband repair tools can handle.
For a full view of how Spectrum Analysis fits into a mastering chain alongside Wave Hammer, EQ, and Statistics, the mastering guide covers the sequence. Spectrum Analysis belongs at the start — before any processing, to understand what you're working with. Then again after each processing step to confirm what changed.
Frequently Asked Questions
Where is the Spectral Analysis tool in Sound Forge Pro?
View → Spectrum Analysis. It opens a dockable or floating window. The Spectroscope (real-time frequency meter) is in the Channel Meters panel — View → Channel Meters, then right-click the meters area to add it. Separate tool, different purpose: Spectrum Analysis is for detailed FFT analysis with snapshot storage and sonogram mode; Spectroscope is for continuous real-time monitoring during playback.
What FFT size should I use in Sound Forge Pro Spectrum Analysis?
For general EQ analysis: 4096 or 8192. For hunting narrow anomalies like specific resonances or hum harmonics: 16384 or 32768. For real-time monitoring where CPU is limited: 1024 or 2048. Higher FFT size = better frequency resolution but slower display refresh. Blackman-Harris smoothing window is the standard starting point for most audio work.
What is the difference between the spectrum graph and the sonogram in Sound Forge Pro?
The spectrum graph shows amplitude vs. frequency at a single moment (or averaged over a selection) — a snapshot of frequency content. The sonogram shows amplitude vs. frequency vs. time — frequency on the Y-axis, time on the X-axis, amplitude as color intensity. The sonogram reveals how frequency content changes over time; the spectrum graph gives a cleaner, more precise view of the frequency distribution at a specific moment.
How do I compare before and after EQ in Sound Forge Pro Spectrum Analysis?
Take a snapshot before applying EQ: select your audio, open Spectrum Analysis, click Set, then click snapshot button 1. Apply the EQ. Select the same audio region again, click Refresh. The original snapshot remains visible in the graph alongside the new analysis. Up to four snapshots can be stored simultaneously for multi-stage comparison.
Does Sound Forge Audio Studio have a Spectrum Analysis tool?
The current Boris FX lineup no longer sells a separate Audio Studio tier. On a legacy Sound Forge Audio Studio installation, check the View menu because feature availability varies by version; if the full Spectrum Analysis window is absent, a compatible analyzer VST is the practical workaround. The Sound Forge review explains the current editor, while the pricing page shows today's Sound Forge and Sound Forge Plus plans.
How do I use Spectrum Analysis for mastering in Sound Forge Pro?
Analyze short, representative selections rather than one long static selection; the current Spectrum Analysis documentation warns that long selections take longer and reduce time resolution. Start at 8192, capture a snapshot, make one EQ change, and refresh the exact same selection with the same settings. Use the graph to verify what changed, then keep or reject the move by listening in Bypass comparison.
Why is the Spectrum Analysis display sluggish or slow in Sound Forge Pro?
Real-time spectrum analysis is CPU-intensive. Three things that help: switch from Filled Graph to Line Graph display mode, decrease FFT size to 2048 or 1024, and turn off stored snapshots. If you're using real-time monitoring during playback, these three changes together usually resolve the lag. On older hardware, running Spectrum Analysis as a static refresh (no real-time monitoring) avoids the issue entirely.
Once the analyzer has identified a repeatable problem, use the Sound Forge EQ workflow for a controlled correction. For steady electrical hum or broadband hiss, follow the hiss-and-hum diagnosis guide before choosing a processor.
Last fact-checked: August 2, 2026 against the current Boris FX Sound Forge 2026 Spectrum Analysis, Spectrum Graph, Sonogram, Spectrum Settings, SpectraLayers integration, and pricing documentation.