User Guide

A walkthrough of the screen layout, what each feature does, and what the settings mean. Come back here whenever something's unclear.

This app has a free Free mode and a paid Pro mode, and some features differ between them. Anything marked PRO is Pro-only. See the Free / Pro section below for details.

Contents

Basics

The basic screen

The top pane is the spectrum, the bottom pane is the waveform. The controls sit in the toolbar along the top. Match the numbers on the screenshot with the list below.

The basic screen with numbers 1-14 marking each control (orange = Pro only) 1 2 3 4 5 6 7 8 9 10 11 12 13 14
The basic screen (Linear / dB). The numbers match the list below.

Available in FreePro only

  1. Freq (frequency axis)Switch between Linear, Log and Piano. Linear shows frequency as-is, Log is a logarithmic view closer to how we hear, and Piano maps the axis to the piano's range (also logarithmic).
  2. Amp (amplitude axis)Switch between dB (logarithmic) and Linear. In Linear mode you can adjust the sensitivity in Settings.
  3. Spectrum zoomPROMagnifies the frequency axis (Pro). Once zoomed in, drag left and right to reach the band you want.
  4. FreezePauses the display and switches to Freeze mode, where the seek controls become available. It becomes [Live] — press again to return to real time.
  5. Input device infoShows the device being analyzed, its sample rate and the frame rate.
  6. Monitor (headphones)Monitor the incoming audio through headphones or similar. Output device and volume are set in Settings.
  7. REC (recording)PROSaves the incoming audio as WAV (Pro). Up to 15 minutes.
  8. PeakToggles peak labels. Up to four peaks are detected at a time.
  9. InfoOpens this manual in your browser.
  10. Settings (gear)Change the input device, resolution (FFT), colors, monitor output and other settings.
  11. Spectrum pane (top)Shows the sound by frequency — horizontal is frequency, vertical is level.
  12. Spectral centroid marker (▼)PROMarks where the sound's energy is centered (Pro) — a guide to its brightness. Hover to read the frequency.
  13. Waveform pane (bottom)Shows the raw waveform. In Pro, you can drag here while frozen to seek through time.
  14. Waveform zoom (vertical)PROChanges the maximum level of the waveform display so quiet sounds can be shown larger (Pro).
Display mode

Frequency axis (Linear / Log / Piano)

The Log frequency axis view
Log view — the one to use for watching music
The Piano frequency axis view, mapped to the 88-key range
Piano view — for checking pitch. Note: Amp is set to Linear in this screenshot.
Display mode

Amplitude axis (dB / Linear)

dB mode makes quiet components easy to see and is good for checking overall balance. Linear mode gives a more direct read on amplitude changes. The waveform pane below updates alongside it.

PROIn Linear mode, some sources can show only a very low peak. If that happens, raise the scale with "Amp Linear Max Lv." in Settings, or tick "Auto" to have it automatically adjust to match the loudest peak. Note: both of these only affect Linear mode — they have no effect in dB mode.

Analysis

Peak labels & peak hold

Shows the peak (maximum) level for each frequency on the spectrum and holds it for a while. The [Peak] button at the top right finds up to four peaks at a time and labels them on both the live trace and the peak-hold trace. Double-click the spectrum to reset peak hold manually at that moment.

PROIn Pro you can toggle peak display, choose whether labels show the frequency, the value or both, customize how long peak hold is kept, and change the color of the peak-hold line.

Peak labels in action (Log axis, Linear amplitude)
The [Peak] button detects and labels up to four peaks on both the peak-hold and live traces
Analysis

Monitor & Freeze

The [Headphone] button lets you monitor the incoming audio directly. The monitor output device and volume can be changed in Settings. Using speakers will cause feedback, so headphones are recommended (if the input source and the monitor output are the same device, monitoring is only available while frozen).

The Freeze button pauses the display so you can inspect it calmly. While frozen, hovering shows the frequency and level at that point, and you can still switch frequency/amplitude display modes. The peak hold from the moment you froze is kept as well, so you can review the most recent peak positions at your leisure.

Moving through time: while frozen, the << >> buttons step in 0.5-second increments and < > step frame by frame. plays forward and plays in reverse, so you can listen as you review. When playback is stopped and monitoring is on, the app loops the audio at that exact moment (1/10 second). In Pro, you can also drag the waveform at the bottom of the screen or spin the mouse wheel to move in 1/1000-second steps, and use the keyboard [←] [→] keys to move a single sample at a time — perfect for pinning down a momentary noise, click, or transient. History length goes back up to 5 seconds on Free, and up to 10 seconds on Pro.

While frozen, a [Live] button appears — press it any time to return to the real-time display.

Piano frequency axis with Freeze mode active — monitor button, playback controls, and waveform drag-seek arrows (Pro)
Piano mode with Freeze active. The [Headphone] button (top right) enables monitoring; ◀ << < / > >> ▶ move and play. Pro lets you drag the waveform below to seek finely
Pro feature

Spectral centroid marker PRO

Show a marker for the spectral centroid on the spectrum — a handy indicator of the sound's "brightness" or balance point. The spectral centroid expresses, as a single frequency, where the sound's energy is concentrated (toward the low or high end). A higher value tends to mean a brighter sound, a lower value a darker, heavier one.

Hover over the marker to read the centroid frequency (Hz). It's a useful reference when comparing how bright different sources sound, or the character of different timbres. You can turn the marker on and off in Settings.

The spectral centroid marker shown below the spectrum axis
The spectral centroid marker (circled in red) — 5.72 kHz for this source
Pro feature

Line/Bar Style, Waveform Color & Zoom PRO

In Pro mode you can customize how everything is drawn. The spectrum can be switched between a smooth line view (good for overall trends) and a bar view that makes individual FFT components easier to read. The ⊖ 1x ⊕ control at along the top magnifies the spectrum along the frequency axis (horizontally) for a closer look. While zoomed in, drag with the mouse to move the visible range.

For the waveform pane at the bottom, the ⊖ 1x ⊕ control at (top right of the pane) magnifies the level (vertically). "Waveform Zoom" in Settings covers both that and the sample direction (time axis, horizontal). Zooming vertically reveals quiet sounds; zooming horizontally reveals the shape of a shorter time range.

The colors of the spectrum, the peak-hold line and the waveform can all be customized as well.

Bar view with zoom and custom colors (① spectrum zoom, ② waveform level zoom)
The bar view follows the FFT resolution. The zoom controls pair well with Freeze. Colors are customizable too.
Pro feature

Recording PRO

The [REC] button at the top right saves the audio being analyzed as a WAV file. It's limited to 15 minutes — meant for short test or reference captures rather than long recording sessions. Files go to the folder chosen under "Recording Folder" in Settings, and the elapsed time is shown on screen. Recording stops automatically at the 15-minute mark, or if the settings change.

Recording UI showing REC button, elapsed timer, and stop button
The recording UI (REC, elapsed timer, STOP)
Reference

Settings reference

Everything in the Settings window, opened from the gear icon.

SettingPlanWhat it does
Audio Device & Analysis
Input DeviceFreeThe audio source to analyze. Entries starting with [Out] are playback devices — pick one to watch music or video playing on your PC. Entries starting with [In] are inputs such as microphones
The circular arrow on the right reloads the list — press it after changing device settings in the OS, plugging or unplugging headphones, or connecting something over Bluetooth
Resolution (FFT)Partly ProSets how finely the frequency range is divided. Choose from 256 / 512 / 1024 / 2048 / 4096 — Pro adds 8192 / 16384 / 32768
Higher values split the frequency range more finely
The input sample rate and the resulting resolution per bin (Hz) are shown just below
Mode (Mono / Stereo)FreeBy default the two channels are mixed down to mono. Choose Stereo and the display splits into two, one for each channel
Frame RateProThe display refresh rate is fixed at 20 per second on Free; Pro lets you choose 20 or 60.
Amp Linear Max Lv. / AutoProChanges the top of the vertical scale when the amplitude axis is set to Linear. Tick Auto and it follows the loudest peak automatically. Note: this has no effect while Amp is set to dB
Monitoring Device / Monitor VolumeFreeSets which device the [Headphone] monitor plays through, and at what volume. Headphones are recommended to avoid feedback. If you pick the same device as the input source, monitoring only works while frozen
General / Window
LanguageFreeChoose the language used throughout the app.
Recording FolderProWhere WAV files recorded with [REC] are saved
Always on TopProKeeps the window above other applications
Transparent (50%)ProMakes the background semi-transparent — handy for overlaying it on a DAW, a video, or a streaming layout
Display & Colors
Spectrum StyleProSets how the spectrum is drawn — a smooth Line, or Bars that let you read each FFT component
Peak LabelProWhat the peak labels show — frequency, value, or both (plus note names in Piano mode)
Spectrum Color / OpacityProColor and opacity of the spectrum
Show Peak HoldProWhether the peak-hold trace is drawn
Spectrum CentroidProWhether the spectral centroid marker (▼) is shown
Peak Hold TimeProHow long peaks are held (1s / 3s / 5s / 10s / 30s / Infinite). Double-click the spectrum to reset manually
Peak Hold Color / OpacityProColor and opacity of the peak-hold trace
Show WaveformProWhether the waveform pane at the bottom is shown
Waveform Color / OpacityProColor and opacity of the waveform
Waveform Zoom (Frequency / Level)ProZoom for the waveform pane. Frequency is horizontal (time axis) and Level is vertical (amplitude). Level can also be changed from the ⊖ 1x ⊕ control at the top right of the waveform pane
The settings window
The settings window with Pro unlocked (all options visible)
Reference

Free / Pro

Even with just the Free version, you get the core features — the real-time spectrum, the waveform display and peak detection.

Upgrading to Pro adds smoother rendering, finer analysis and display customization. You can purchase it from the "Upgrade to Pro" button in Settings.

What Pro unlocks
  • Graphs are drawn at a smooth 60 FPS
  • Higher FFT resolutions (8192, 16384, 32768) let you inspect the lower part of the audible range in much finer detail
  • In Amp Linear mode — handy for pitch analysis — you can change the top of the scale so quiet sounds are easier to read
  • Seek in 1 ms or single-sample steps while frozen, for much closer analysis
  • Zoom into a frequency band on the spectrum, or into the waveform, to examine a sound closely
  • Record the audio you're analyzing and keep it for later
  • Customize the display and set the colors to your liking
  • Always-on-top and a transparent background let you overlay it on another app or a game and follow the sound visually
Support

FAQ

The frame rate is lower than what I set
60fps display and high FFT resolutions increase processing load. Depending on your PC, input device, other running apps, and display settings, the actual rendering rate can drop below what's selected.
Is there a limit on recording length?
Recording is capped at 15 minutes and stops automatically at that point. It's designed for short test/reference captures, not long-form recording.
Is my audio data sent anywhere?
No. All analysis happens locally, and audio data is never sent to an external server. Recorded files are saved to a folder you choose.
Can I use this as a calibrated measurement instrument?
This app is a visual inspection tool, not a calibrated measurement instrument. It's not intended for legal, professional, or certification-grade acoustic measurement. Displayed values are affected by your input device, OS volume settings, and environment.
Have a question not covered here? Feel free to reach out on X or through a store review.