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kristarella.com

kristarella.com

Happiness Engineer at Automattic, lover of knitting, crochet, sci-fi and more

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You are here: Home / Entertainment / Music / Speed up an mp3

Speed up an mp3

28 June 2007 by kristarella

audacity logo

While studying for exams I’ve found it really useful to listen to the recordings that are made of our university lectures. They make the lectures available to download as mp3s for students enrolled in the course. Very handy, especially for the lectures I wasn’t able to get to; it’s quite difficult to learn anything if I just sit down an stare at the handouts, or at someone else’s notes.

In listening to these lectures I’ve discovered that when you’re not watching the person speak and you’re not able to see their actions and facial expressions, people actually speak very slowly. I was hoping that since iTunes is my default player it would be able to play tracks a bit faster. Sadly after much searching I only found a script that would pause iTunes and open the track with Quicktime to play it faster. This wasn’t ideal, it didn’t seem like it could be paused or stopped and started again from Quicktime.

So I turned to my friend, open source software. Audacity is a free, open source program that can record and edit sounds. It can import and export WAV, mp3 (with LAME encoder installed) and Ogg Vorbis, among others. It can work with up to 16 tracks and it has a large range of features. For this exercise I used the change speed, change pitch and amplify effects.

audacity edit view

To start, I opened the mp3 file in Audacity. In the above image I’ve already selected the part of the file that I wanted by dragging the mouse across it, and removed the rest with the trim outside selection button.

audacity change speed

To change the speed you need to select the whole file (represented as wav peaks) and go to Effect > Change Speed…. That will give you a window (as shown in the image). I dragged the blue cursor up so that I was changing the speed by about 50%. I find that to be a reasonable increase while still being able to understand the words. You could play with the speed to see how fast your file needs to go.

If you play back your file as is, you’ll find it fairly difficult to understand because of the the chipmunk element, it also sounds pretty funny. Go to Effect > Change Pitch…. Drag the blue cursor like for the speed, but this time take it down about 30%. I find with a 50% increase in speed, a 30% decrease in pitch makes the speaker sounds fairly normal.

It can also be handy to use Effect > Amplify to make the file a bit louder; some lecturers are softly spoken. 😉

Hazar for Audacity and for open source software! Also kudos to the uni for recording the lectures and making them downloadable!

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Filed Under: Music, Technology Tagged With: free, Free Software, tools

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Comments

  1. Justin says

    28 June 2007 at 11:29

    We have been using Audacity for a few years…when Dad started his radio show and recording from home, we used that to record and edit…it was good, i still use it to record songs off YouTube videos that i can’t get an mp3 for…hehe…i mean, no i don’t…that’s illegal!
    …i think

  2. kristarella says

    28 June 2007 at 14:19

    Heh, dork! 😀

  3. Justin says

    28 June 2007 at 16:29

    Me, or you? Coz if you mean me…then, that is just absolutely and utterly proposterous!
    …I hope i spelt that right 😛

  4. kristarella says

    28 June 2007 at 21:36

    I meant you because of your little illegal rant. 😛

  5. mrDween says

    28 June 2007 at 23:36

    You’re correct – people can listen to much faster text than they think and still understand it.

    I recently heard a story on ABC about Ron McCallum, Dean of Law at Sydney University, who has been blind most of his life. He struggled through uni until he was able to get a scanning device which reads text and reads it back to him at roughly twice the speed of normal speech. I couldn’t understand a single word, but he’s trained himself to follow it. Anyway – after a few weeks of listening at one speed, see if you can speed it up and still follow it. You too may be able to listen to incredibly fast text one day…

    Nice redesign, by the way. Love the tree. Maybe you can make a new tree for each season and keep up with the weather.

    .e

  6. Justin says

    29 June 2007 at 13:59

    That’s a good idea Ed, I like it…Kristen, do it!! maybe blue for winter, red for summer, etc etc?

  7. kristarella says

    29 June 2007 at 17:58

    Heh, I might. It would keep things fresh.
    Too late though Jus, winter is already red! I’m thinking that winter red; spring pink (for flowers), or maybe green, or maybe green with pink splashes; summer could be sky blue, for a sunny day; autumn probably brown and orange… if the tree motif sticks around for a year that is!

  8. fabulous says

    9 October 2007 at 23:55

    ..whew, i want to produce a chipmunk version of a song.. but i can’t, can u heLp me.. e-maiL me.. tnx..

  9. fabulous says

    10 October 2007 at 00:20

    ..uhmm,, sorry i knew it know.. hehe!! ..thanks!! ^^

  10. kristarella says

    10 October 2007 at 07:04

    I would have said that you speed it up and don’t lower the pitch very much… glad you figured it out 🙂

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