Slowing Down a Recording

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These techniques are for listening with a computer.

Audacity audio editor (free)

annise (Anne) wrote on 2009 Mar 04:

Audacity will do this - and its free - just need to change the tempo in effects.

Amazing Slow Downer from Roni Music (pay)

dusty wrote on 2009 Mar 04:

It is a commercial product ($49.95 US), the Amazing Slow Downer from Roni Music. It's targeted to music files but it works on audio books.

I downloaded and tested it on a LibriVox file and it does work. Lots of settings, but I just tried with the default. It doesn't change the pitch of the voice. It looks like you can even re-save the files in batches after slowing them down. For Mac & Windows.

Slow Me Down plugin for Winamp from Roni Music (free)

Cori wrote on 2009 Mar 04:

I have used, and loved, their freeware Winamp plugin. Though I didn't realise I had such an old version of Winamp on the other computer. I used it for slowing down music, but it would work okay on voices, I think, since you can tweak the pitch too if need be. An excellent choice if the listener has an old computer (mine was on Win 98.) I couldn't save the slowed file, but it was fine for listening on the spot, and can be easily turned off to listen at normal speed without losing preferred settings (though those will vary by book anyway.)

harvey wrote on 2009 Mar 04:

Notice that, even though the Web page for this plugin says it "only works with Winamp 2" and "does not work with Winamp 3 or higher", I just tested it with Winamp 5 (the latest major version) and it does work.

One change speed (tempo) and pitch independently. Speed can be regulated from 1/4 faster to 1/2 slower.

However, there were some imperfections. Occasionally, the sound would be a bit garbled -- noticeable, but not real objectionable. Also, I tried it with a !LibriVox recording by a female reader. At all slower speeds, her voice sounded hollow like she was talking inside a box.

If you try it out, keep in mind there's a brief delay in between changing the setting for speed or pitch and the software catching up and applying the change.

Nullsoft Signal Processing Studio DSP plugin which comes with Winamp

Great Plains (Daniel) wrote on 2009 March 04:

WinAmp's built-in Nullsoft Signal Processing Studio DSP plug-in has a tempo control. Go to Preferences > Plug-ins > DSP/Effect > Nullsoft Signal [...] > Enable processing, and then use the vertical slider to change the speed. Takes a second to kick in after you make a change.

harvey wrote on 2009 March 04:

In my installation of Winamp, the Nullsoft Studio has 17 different DSP (i.e., Digital Signal Processing) functions which can be individually loaded. The only one I can see which lets you slow down a recording is labeled: "justin - simple pitch and tempo (half-2x) control". It's a speed control, which means it changes tempo and pitch together.

VLC Media Player (free)

harvey wrote on 2009 Mar 04:

The free media player VLC has several types of controls for increasing or decreasing playback speed, like you can do with a DVD player. However, changing the speed of playback also changes the pitch of the voice.

Across the width of VLC's small window, there is a progress bar and slider. On either end are double triangles (arrow heads), which increase or decrease playback in fairly big steps.

At the bottom of the window is a status bar divided into three segments. The one in the middle shows the playback speed. Right-click on that segment (on the displayed speed) to open a speed control slider, which allows finer control than the double triangles.

Microsoft Windows Media Player (free)

harvey wrote on 2009 Mar 04:

Also, Windows Media Player (version 10; don't know about others) has three speed control settings.

  • Play [menu] > Play Speed