Last week Shelly Fryer‘s (@sfryer) 3rd and 4th grade students created an excellent paper slide video to culminate three weeks of classroom study about bats. In this post, I’ll explain how I helped Shelly “normalize” the recorded audio of her students (so even the quietest students are loud enough to be clearly understandable in the video) using the apps iMovie for iPad and Auphonic Recorder for iPhone. I’ll also explain how I helped Shelly add copyright-friendly music from the YouTube Audio Library as background music for the video.

Audio normalization is a “process of uniformly increasing or decreasing the amplitude of an audio signal.” In this case, we wanted to increase the volume of the audio portions recorded by the quietest students in Shelly’s class so they can be clearly understood just like the louder students. The amplitude of the soundwaves in the final, normalized audio file and the original audio recording are shown in the screenshot below from the Auphonic.com website. Notice how the original recording (below) had some very loud (tall) waveforms as well as very quiet (short) waveforms. The final, normalized audio recording (at the top) is relatively loud and uniform throughout. This is what you ideally want a normalized audio recording to look like.

These are the steps we followed to create the final video with normalized audio and background music. We used an iPad, an iPhone, and a MacBook laptop to complete these steps, but they could also have been done with a single iOS device (iPad or iPhone) and a MacBook.

  1. AirDrop the original recorded video (in default mp4 format) from the iPad Photo Roll to a MacBook laptop.
  2. On the MacBook, open the video in QuickTime Player, and choose FILE – EXPORT – AUDIO ONLY. (This creates a .m4a audio file)
  3. Open Auphonic Recorder on the iPhone and tap to start “a new production.”
  4. AirDrop the original / unprocessed paperslide audio file from the MacBook laptop to the iPhone and choose to open it in Auphonic Recorder.
  5. Select the desired Auphonic audio processing settings. We kept the “adaptive leveler” on as well as “loudness normalization,” and chose to create a 160 kbps MP3 file. Tap “Save and Start Production” to process the file with these settings. (Note you may need to create a free account on Auphonic.com to do this. Free accounts come with 2 hours of audio processing time per month.)
  6. Since there does not appear to be a way to directly share the processed audio file from the Auphonic iOS app, visit the Auphonic.com website, login with your credentials, click on your production and click to download the normalized/final MP3 file.
  7. Start a new iMovie project on the iPad, using the original paper slide video.
  8. Extract the audio in iMovie from the video, and then delete that original / unprocessed audio track.
  9. From the MacBook laptop, AirDrop the normalized MP3 audio file to the iPad and choose to open it in the current iMovie project. Since the length of the original audio file has not been changed, it’s just been normalized / processed by Auphonic, it should sync just like the original to the video footage.
  10. On the iPad in iMovie, choose to export the edited movie to the Camera Roll as a 720P video.
  11. On the iPad, start another new project in iMovie and import the edited video you just saved to the Camera Roll. (This is a video version which now includes a normalized audio track.)
  12. On the MacBook laptop, use the YouTube Audio Library of free, copyright-friendly tracks to download a MP3 audio file you want to use as background music for your video. Note you can filter by mood, instrument, and other details to find a suitable track.
  13. On the MacBook laptop, AirDrop the downloaded MP3 music file to the iPad and choose to open it in the current (second) iMovie project.
  14. On the iPad in iMovie, reduce the volume level of the imported background music as desired. (We reduced it from 100% to 74%) Play the video which now includes normalized narration audio as well as background music. Make sure the background music does not overpower the narration. Reduce its volume further if necessary.
  15. On the iPad in iMovie, choose to export the edited movie to the Camera Roll as a 720P video.
  16. From the iPad Camera Roll, upload the final video (which now includes a normalized audio track as well as background music) to your YouTube channel.

Since iMovie for iPad only supports the importing of one audio track per project, it was necessary to import audio files into two different projects. If you choose to use a more advanced iPad video editing app, like Pinnacle Studio Pro ($12), you could import both the normalized audio track and the background music file into the same project and just export the finished video one time.

Have you had success using other methods to normalize student audio recordings for iPad video projects? If so, please share your techniques as a comment here or by reaching out with a Twitter reply to @wfryer. There are a lot of steps to the workflow described here, but it did work and the results are MUCH better than the original, un-normalized video recording!

For more tips, apps and strategies useful for creating multimedia projects in the classroom, visit ShowWithMedia.com.


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If you're trying to listen to a podcast episode and it's not working, check this status page. (Wes is migrating his podcasts to Amazon S3 for hosting.) Remember to follow Wesley Fryer on Twitter (@wfryer), Facebook and Google+. Also "like" Wesley's Facebook pages for "Speed of Creativity Learning" and his eBook, "Playing with Media." Don't miss Wesley's latest technology integration project, "Mapping Media to the Curriculum."

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