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AvailableMusic Production

Spledio

See your audio. Fix just the part that's wrong.

Spledio shows your audio as a picture of its sound (a spectrogram). Select one sound in that picture, such as a cough, a ringing note or a hum, and turn it down, up or off without touching the rest.

Everything runs on your Mac: no account, no uploads, no internet connection. Your original file is never changed.

macOS

Download for MacView on GitHubUser manual

Version 1.3 · macOS 15 or later · Apple silicon · Signed with Developer ID and notarized by Apple.

Pricing: Free · open source under GNU GPL version 3 only (GPL-3.0-only). macOS 15 or later · Apple silicon.Support: apps@iacompa.comLegal: Privacy · Terms · Support · GPL-3.0-only · Source code
Spledio app icon

How it works

The screenshots on this page show one 16-second example recording: piano chords, a whistle from 5 to 9 seconds and a cough at about 11.6 seconds.

  1. 1. Open a file. Drag a recording onto the window, or choose File → Open Audio… (⌘O). WAV, AIFF, FLAC, MP3, Ogg Vorbis, Opus, CAF and other formats open. Your original file is never changed.
  2. 2. See the sound as a picture. Time runs left to right, pitch bottom to top, and brightness shows loudness. A steady tone, such as a whistle or a hum, is a thin horizontal line; a short click or a cough is a vertical burst.
  3. 3. Draw a box around the sound. The Rectangle tool is ready when you start. Box in just the sound you want to change, and a small level bar appears next to it.
  4. 4. Click − / + or Silence. Each click on − or + makes that part 1 dB quieter or louder. You can also drag the slider or click Silence. Everything outside the box stays exactly as it was, and no time is cut.
  5. 5. Listen, then export. Press Space to play; changes are heard while it plays. File → Export Audio… (⌘E) saves the result as WAV or FLAC.
Spledio with a box drawn around the whistle line, from 4.85 to 9.15 seconds and 2,650 to 3,300 Hz. Above the box, a level bar reads Selection, with minus, a slider, plus, 0 dB, a play button and Silence.
A box drawn around the whistle, with its level bar: −, slider, +, play and Silence. Example recording.

The whistle, then without it.

Turned down to −40 dB, the whistle’s line disappears from the picture. The piano outside the box stays exactly as it was, and the recording keeps its length.

Spledio 1.3 in its dark theme with a 16-second example recording open. The spectrogram shows piano chords as stacked horizontal lines, a thin bright horizontal line near 3 kHz from about 5 to 9 seconds, and a bright vertical burst near 11.6 seconds. The bar under the spectrogram has Zoom − and +, Frequency − and +, Whole File, Selection, and Adjusted areas with Show and Hide.
Before: the whistle is the thin bright line near 3 kHz, from 5 to 9 seconds. Example recording.
Spledio after the boxed whistle was turned down to −40 dB. The bright line inside the box is gone, the level bar reads Area 1 at −40 dB, and the Adjusted Areas panel lists Area 1 at −40.0 dB.
After: the whistle turned down by 40 dB. The line is gone, and the box stays listed as Area 1. Example recording.

Change your mind.

Every adjusted area stays outlined with its name and level, such as Area 1 · −40 dB. Click inside it to change it again, or press Delete to remove the change and get the original audio back exactly. The Adjusted Areas panel lists every area.

Want a clear view? Show / Hide, next to Adjusted areas in the bar under the spectrogram, hides the outlines (Shift+H). It changes only the display, not the sound. The same bar has Zoom − / +, Frequency − / +, Whole File and Selection.

Spledio with two adjusted areas. The whistle box stays outlined and labelled Area 1 · −40 dB, and a tall box around the cough near 11.6 seconds has a level bar reading Area 2 −18 dB. The bar under the spectrogram reads Adjusted areas (2), with Show and Hide.
Two adjusted areas: the whistle at −40 dB and the cough at −18 dB. Each stays outlined with its level. Example recording.
Spledio zoomed in on about 4 to 10 seconds and 1.5 to 4.5 kHz. The whistle box fills the middle of the view, outlined and labelled Area 1 · −40 dB, with the turned-down whistle as a faint line inside it.
Zoomed in on the whistle. Zoom with the − / + buttons in the bar under the spectrogram, ⌘ + scroll or a trackpad pinch. Example recording.

Handy keys

↓↑
1 dB quieter / louder; hold Shift for 6 dB
0
Silence the selected part
Delete
Remove the adjustment from the area you picked
SD
Hear only the selection / hear the difference, what an edit removed
⌘Z
Undo, up to 200 steps
Shift+H
Show or hide adjusted areas
F1
Built-in step-by-step tutorials

Click the spectrogram first so the keys reach it. Everything else is in the user manual.

Good to know

  • Needs a Mac with Apple silicon and macOS 15 or later.
  • No Windows or Linux installer yet.
  • Export is WAV or FLAC.
  • Long files use a lot of memory: a 60-minute file needs up to about 6 GB while a long area is applied.

Found a bug or have a question? Open an issue on GitHub Issues with your Spledio version (Help → About), your macOS version and the steps that cause the problem.

Spledio is an independent project and is not affiliated with or endorsed by any maker of commercial audio software.

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