Posts Tagged ‘Audacity’

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Editing a digital voice recording: 2: Editing in Audacity

June 1, 2008

Once I’d successfully imported the converted WAV file in to Audacity, it was time to do File > Save As to make a copy then to start editing the copy. Some of the things I needed to do were:

  • Remove as much background noise as possible (see Scott Nesbitt’s excellent article “Cleaning up audio files with Audacity” for how to do this using Effect > Noise Removal).
  • Remove the “um’s and ah’s” and unrequired silences as far as possible without detracting from the ‘personality’ of the presentation. (Select the piece of the waveform you don’t want, then click the DEL key to delete it.)
  • Add silence where it was needed (Generate > Silence).
  • Add a tone to tell the listener to go to the next slide if they are viewing the slide presentation at the same time as listening to the audio (Generate > Tone; I used these settings: Waveform: Sine; Frequency: 440.00; Amplitude: 0.25; Seconds: 0.25)
  • Reduce the file size by changing the settings (drop-down arrow next to the track title in the summary box on the left). The settings I chose were 16-bit, 8000 Hz, Mono. With these settings I went from an original size of 75 MB to 62 MB, but with my editing I had also reduced the time from 75 mins to around 65 mins, so I’m not sure I saved anything; it looked as though about 1 min of voice is about 1 MB of file size.
  • Still looking for a smaller file size, I also found I could change my MP3 output bit rate preferences from 128 to 64 (Edit > Preferences > File Formats tab) – this reduced the file size to 31 MB with no apparent loss of voice quality (remember, this wasn’t a super good recording in the first place).
  • Save the file as a WAV file and an MP3, as well as save the project (AUP file format).
  • Add metadata (complete the ID3 tags as fully as possible when you save the file; I selected Speech as the genre).

All this required a lot of testing: zoom in, play, stop, rewind, play, test, etc. It probably took me some five hours to edit the 75 min presentation. Remember, I am totally new to this. Now that I’ve written down these instructions, I’d hope to be much quicker if I have to do this sort of thing again.

[Links last checked August 2012]

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Editing a digital voice recording: 1: Converting the WAV file

June 1, 2008

Audacity didn’t recognize the WAV file from my DVR when I tried to open it using File > Open, even though Windows Media Player played it in its native format without any problems.

I searched Audacity’s (unhelpful) Help file for clues, then the internet. Some clues later, I tried importing the file (Project > Import Audio), but that didn’t work, and nor did importing it as a Raw file (Project > Import Raw File) which was Audacity’s suggestion in the error message.

Back to the internet where I found another clue—try opening the so-called WAV file in Windows Sound Recorder (Start > Programs > Accessories > Entertainment > Sound Recorder), then save it as a WAV file again (File > Save As). That worked—or so I thought. I now had a WAV file that Audacity could import. But only a few minutes imported. Actually, the entire 75 mins imported, but it was compressed into these few minutes which meant I sounded like a chipmunk on speed!

Off to Google again where I found a forum post that suggested using Switch audio converter. So I downloaded and installed it, then successfully converted the DVR’s WAV file format in to a recognisable WAV format. Now I had 75 mins of real time audio which I then imported into Audacity (Project > Import Audio).

Continue to Part 2: Editing in Audacity.

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Editing a digital voice recording: Overview

June 1, 2008

The two articles following this one detail how I created my first digital voice recording and edited it using Audacity. As I didn’t know how to use the hardware or the software, there was some learning involved. To save me time in the future—and to help you out in case you ever have to do something similar—I’ve documented my ‘newbie’ steps.

Please note: DO NOT edit your original file—make at least one copy and edit the copy. That way you can always go back to the source file if you make any serious mistakes.

Scenario

Earlier this year I purchased a cheap ‘no name’ digital voice recorder (DVR). I spent a little time figuring out how it worked (the instructions were really bad) and tested it by recording small snippets. My goal was to record my conference presentation at the WritersUA Conference in March, convert it to MP3, and make it available as a download from my website.

However, in addition to the bad instructions, the DVR recorded a lot of background noise if I didn’t have it close to my mouth. Even then, the sound quality was acceptable, but only just. This was not going to be good for a conference presentation as I had hoped to put the DVR on the lecturn or in my pocket. I figured that I needed a clip-on ‘radio mike’ (there was an outlet for an external microphone on the DVR), so when I was in the US I purchased one from Radio Shack and tested it out.

I successfully recorded my presentation (WAV file) and downloaded it to my computer. I also downloaded and installed Audacity and the LAME MP3 converter (both free).

When I tried to open the DVR WAV file in Audacity, I got an error message that the file format was not recognised. It seems some DVRs record a ‘WAV’ file, but it’s not a true WAV file.

Continue to Part 1: Converting the DVR WAV file and Part 2: Editing in Audacity.