Over the past few days, I was trying to find an app that I can adjust the speed of the audio files during playback – and preferably with an option to save/export the adjusted speed.

Why do I need that? Because ballet exams are approaching and the Royal Academy of Dance now allows the use of CD music for Pre-Primary and Primary grades. And rightfully so, because the tracks are entirely instrumental and uses lots of percussion arrangements to enliven the exercises. In fact, the piano arrangement is just uninspiring.

I have been tasked to alter the speed of some of the exercises so that it is more danceable. I usually use Adobe Audition to do the editing, but this year I thought I could use a portable computing device like the iPad to do the job.

So I tried to search what I wanted using these keywords: Audio, Speed, Tempo, Change, Time, WAV, MP3, Save, Export

It led me to Reforge for iPad, currently the only iOS app that allows me to export the new tempo into a new file. I paid US$5.99 and tried it, but soon found myself disliking the interface. Firstly, it is rather buggy. Some features stopped working and the app even hung the iPad. Also, the tempo rendering takes almost 1 minute, which is too long a wait to listen to the adjusted speed (though I must say the quality is quite good).

My quest continues and it appears after I dropped the ability to export, I got a handful of apps that can do real-time tempo adjustment and playback.

My favourite would have to be iLift for iPhone. You can just by semitone step, fine-tune within a semitone, and temp by percentage. The buttons are big and easy to adjust, and when running full-screen on iPad, you can’t miss the buttons. Changes are on-the-fly. The only minor bug is that when I paused the music and want to start from another point, the app will still playback the previous point before resuming from the new point. It is rather irritating and disruptive. When you want to choose from the song list, the current song will stop playing. The tracks available has to store within the app, so if you want to use your iPod songs for adjustment, you have to add them first.

The equivalent app in Android would have to be Audio Speed Changer. An added advantage is the display the waveform. And I can choose the next audio file without disrupting the current playback. But to adjust the speed would require the user to invoke a pop-up window. In the window, I can adjust by single percentage via a wheel or do vast adjustments via a drag bar. There is no option to adjust tempo, but that’s the point about this app. I can select any song immediately from the Android phone library, the display list is a flat hierarchy and not in folders. Not an issue, because there is a search bar to get the song you want instantly.

Whichever app to choose depends on which platform you are using. But if you, like me, have both platforms, which one would I use? iLift for iPhone costs US$9.99, extremely pricey but worth the money if you need the functions as provided. Reforge for iPad costs US$5.99, and certainly more value for money with the list of audio features available. The drawback is the slow rendering of tempo changes and buggy. Audio Speed Change for Android is free, and offers only tempo changes. A paid version is in the works which will offer more premium features.


  1. i am a tap dance teacher and for some reason my usual desktop software wouldn't slow down some music enough for one of my students. but Audio speed changer did! i wouldn't have found it were it not for your blog! thanks!

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