On a Mac, use Audacity’s Sliding stretch to make a generated tone slow down and drop in pitch, then fade its tail to silence. This creates a tape-stop-style ending within the effect’s documented limits. Audacity’s Sliding Stretch manual describes the gradual speed and pitch controls.

This walkthrough starts with a synthetic sine tone and finishes with an exported sound. The settings are an illustrative recipe, not results from a listening test. You will define the beginning and end of the change; Audacity supplies the movement between them.

Which Audacity workflow applies on a current Mac?

Audacity’s official Mac download page lists version 4.0.1. The Audacity 4.0 release notes explicitly list Time Tracks among the unavailable features, and the 4.0.1 release notes do not announce their restoration. This matters because older instructions commonly use a Time Track for this task. Follow the current effect workflow below instead. Download for macOS, Audacity 4.0.0 release notes, Audacity 4.0.1 release notes

Here, automation means a calculated change across selected audio. You enter endpoints and apply processing, rather than recording a knob movement during playback. Sliding stretch controls tempo and pitch independently; its documented limits are −90% to +500% for tempo and −12 to +12 semitones for pitch. It cannot reach zero playback speed, and it does not document a mechanically linked tape-speed curve. A fade supplies the final silence. Sliding Stretch

Generate a simple sound with a known starting pitch

Start with one tone so that the task has only three creative decisions: where the slowdown begins, how far the pitch falls, and where the sound disappears. Avoid adding other effects until those decisions work together.

  1. Choose File → New to create an empty project. This keeps the example separate from any other audio you are editing. File
  2. Open Generate → Tone.
  3. Set Waveform to Sine, Frequency to 440 Hz, Amplitude (0-1) to 0.3, and Duration to four seconds.
  4. Apply the generator. These are example values; the documented generator provides waveform, frequency, amplitude and duration controls. Tone

A sine wave gives this exercise a clear reference: one starting frequency, without the harmonics of a more complex waveform. The chosen amplitude is simply a working level for the example. You can later regenerate the same settings with a different waveform if you want another texture. Audacity documents the available waveform choices in its Tone reference.

Save the unprocessed project with File → Save, then use File → Save as to create a separate working copy. The first save lets you choose a local destination; the second preserves a version you can return to when comparing different endings. File

Apply a gradual speed and pitch drop

For the first pass, leave the first three seconds steady and process only the final second. Click inside the waveform at approximately three seconds and drag to its end. Dragging within the waveform makes a time-range selection; clicking the clip header selects the clip itself. Confirm that the highlighted region covers the tail you intend to change. Selecting and moving

With that tail selected, open Effect → Pitch and tempo → Sliding stretch. Enter the following illustrative settings, using the semitone fields for pitch, then apply the effect. Audacity documents this menu location and the four endpoint controls. Sliding Stretch

Control Example value
Initial tempo change 0%
Final tempo change −50%
Initial pitch shift 0 semitones
Final pitch shift −12 semitones

The numerical idea is straightforward. A 50% reduction leaves half the original rate. An octave downward halves frequency, so the pitch endpoint for a 440 Hz starting tone corresponds to 220 Hz. These endpoints describe the intended half-speed, octave-down relationship; they do not establish that the two independent controls follow an identical relationship at every intermediate instant.

Treat the selected one second as source material, not a promise of a one-second finished transition. After processing, look at the new tail before choosing the fade. Designing the final disappearance against the processed result avoids basing the next edit on an obsolete endpoint.

Turn the slowdown into a finished stop

Select roughly the last quarter-second of the processed audio, extending the selection all the way to its new end. Choose Effect → Fading → Fade Out. There is no settings dialog: the effect immediately reduces the selected audio linearly in amplitude to silence. The selection itself determines the fade’s duration. Fade Out

The quarter-second suggestion is an editorial starting point. Choose a shorter selection if you want more of the descending tone exposed, or a longer one if you want the sound to disappear earlier in the descent. Apply the fade only after deciding which portion of the pitch movement should remain prominent.

If you accidentally select the entire sound before fading, the level reduction will span the entire sound. Return to the version before that fade and select only the intended ending. Audacity’s fade documentation confirms that the operation covers exactly the selected interval. Fade Out

Adjust the result without losing track of the settings

Make comparisons from the saved unprocessed version, using the same generated tone each time. Change one decision per version so you can tell which adjustment produced the difference. The following sequence is a practical design method, not a set of measured results.

  • Choose the onset first. Compare processing only the final half-second with processing the final second or two. Decide how much steady tone should precede the descent.
  • Choose the depth second. Keep the onset fixed while deciding how pronounced the downward movement should be.
  • Choose the disappearance last. Move the fade’s starting point while keeping its end at the end of the audio.

Use a simple diagnostic order when the result differs from your intention: check the selected region, check both initial values, check both final values, and finally check the fade selection. This separates an editing mistake from a creative choice without requiring additional effects.

Keep the feature boundary in mind when choosing deeper settings. A full stop would require a zero rate, which falls outside the documented tempo range. Matching the illustrative endpoints above also does not turn this effect into linked varispeed processing. Use this workflow when a descending, slowing sound that ends in silence meets the task; an exact tape-transport simulation requires a different capability. Sliding Stretch

Export the complete sound and check its ending

Save the working project, then open File → Export audio. For this single-sound project, choose Export full project audio under Type. This prevents the final fade selection from accidentally becoming the only exported region. Audacity also offers selection and loop-region export, so the scope deserves a deliberate check. File

Saving keeps the editable project; exporting creates a rendered audio copy. Exporting leaves the project’s tracks, clips and effects intact. Keep both files if you expect to revise the transition later. Export Menu

Play the exported file from its beginning and check three things: the steady opening is present, the descent begins where you intended, and the ending reaches silence. Once those agree with your chosen design, you have a reusable synthetic sound with a tape-stop-style ending—and a saved starting point for making another variation.

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