Adobe Audition
Adobe Audition Podcast Tutorial
for speech recordings
This tutorial was originally written in 1998 as a tutorial for creating streaming audio (aka podcasts) using CoolEdit 96. Since 2003, Adobe bought out Syntrillium and CoolEdit Pro became Adobe Audition; CoolEdit 2000 later became Adobe Soundbooth.
This basic tutorial will show you how to use Adobe Audition (or any similiar audio editing program) to record, edit and compress a sound file suitable for making available on your site for streaming audio.

1) Get a sound editing program
Since Adobe Audition / Soundbooth are fairly expensive (about US$350 or US$200 respectively), you can use any decent audio editor you have access to. One free alternative is Audiacity, an open-source product, which as a bonus is available for Windows, Mac and Linux. The screenshots and the step-by-step directions won't match exactly if you use a program other than Audition, but the basic principles contained herein apply no matter what software you use. For a specific tutorial on Audacity, see here.

2) Start recording
2a) I'll assume that you've got your audio source (tape deck, MiniDisc, mixing board, etc) properly connected to the line-in on your soundcard and got the Windows Mixer set to record off line in (your soundcard documentation should cover these steps if you're not sure how). In brief (assuming Windows XP or similar): Volume control panel
  1. Physically plug your audio device into the "Line-In" jack on your soundcard
  2. Go to Control Panel -> Sound and Audio Devices -> Device Volume|Advanced
  3. Change to recording level mode by going to Options -> Properties -> Adjust volume for|Recording (and make sure all boxes below are checked), then click OK
  4. Check the "[x] Select" box under the appropriate source, which could be either "Line In", "Analog Mix" or "What U Hear".
  5. Make sure the volume slider is high enough for the selected source. Usually set at 100% is good, and then adjust the recording level with your playback device. However, if you get distortion and/or you have you set your device playback level below 20% volume, adjust this slider so that playback volume and recording volume are both around 50%, and you're not getting clipping or distortion in your recordings


Record Button Start up Adobe Audition, then click on the Record button (red dot in the toolbar area in the lower-left corner of the screen). You will be presented with a dialog to select channels and frequency. Recording Time Always use 16-bit, never use 8-bit or 32-bit audio format (8-bit sounds very bad and higher than 16-bit is not well supported). You want to capture the optimal sound quality during the recording phase and worry about compressing the sound later. Frequencies above 44100Hz are not supported on all sound cards, so stick with 44100. If you have a stereo source (for music only, stereo for speech is completely unneccesary) you should select "stereo", otherwise select "mono".

Recording Time 2b) If you've selected Timed Record (see Tips section below), a dialog box will appear asking you to enter the time in minutes and seconds you want recorded (this example shows 45 minutes). It doesn't hurt to record a little more just in case your time estimate is slightly off - it's easy to trim excess. If you have not enabled Timed Record, skip to 2c). Note: Make sure Start Recording is set to "Right Away".


2c) Recording is now in progress, and will continue until you either click the Stop button (or hit the Escape key) or until the specified time has elapsed if you have Timed Record enabled. Peak Volume Keep an eye on the volume meter (make sure "Show Levels on Play and Record" is checked under the Options menu) and make sure the level never goes above -1dB at any time. It's far better to keep the recording volume a little on the low side (with peaks around -6dB) and amplify it later rather than record at too high a level because once the audio is clipped it's pretty much impossible to make it sound good again.

3) Edit the recording
Unprocessed Recording 3a) You should now have a recording that looks something like this picture. If you haven't worked with an audio-editing application such as Audition before, left to right represents time, and up and down represents volume. Options | Amplitude | Normalize This picture shows a sample recording as it might appear before you do any editing. You can see that the recording is not as loud as it could be (it doesn't reach all the way to the top and bottom of the screen). The first edit we will do is to "normalize" (amplify as much as possible without clipping). To do that, click on the Transform menu, then under the Amplitude submenu, click on Normalize.... Normalize Dialog Set the options in the following dialog to match this screenshot (the Normalize Left/Right Equally option is disabled if you have a mono recording). I suggest setting to 98% rather than 100% to avoid possible clipping in the decoding phase of the final compressed file.

Normalized Recording 3b) The file should now look something like this, with the loudest portions reaching all the way to the top and/or bottom of the screen. The next step we will do will make the audio easier to listen to for Options | Amplitude | Dynamics Processing the average computer's speaker design, especially for speech.
Dynamics Processing Dialog
You can see that the loudest parts of the recording reach maximum volume, but most of the time the average volume is much closer to -5dB, -10dB, or even lower. To make speech easiest to understand, it's best to have the volume of all parts as close to the same as possible. To do this, we'll make use of the Dynamics Processing feature in Audition, which you Dynamics Processing Dialog, Traditional tab can find under the Transform menu, then under the Amplitude submenu, click on Dynamics Processing... In the dialog that comes up, you will have to create the profile yourself, there is no preset that exactly matches what we want to achieve here. First, make sure the Splines checkbox is checked, then drag the square from the upper-right corner of the grid down a little to -10dB. Then click in the grid where you see the other two white boxes in this picture, at approximately -20dB/-10dB and -30dB/-30dB. Alternately, it might be easier to enter numbers on the Traditional tab of the dialog, as shown here. Select Compress 50:1 Above -20dB, Expand 2:1 Below -20dB, and Flat Below -30dB. Make sure you enter negative numbers for those dB thresholds. Enter 10 for Output Compensation. Click back over to the Dynamics Processing - processed Graphic tab to make sure the graph still looks like the shape you see illustrated here - if you mis-entered some numbers the shape will be quite different and you should double-check your numbers. After you click OK and the processing is complete, the file should look something like this, with almost all the volume at about the same level, but not at maximum volume. Perform the same steps as we did early to normalize the volume to 98% again: click on the Transform menu, then under the Amplitude submenu, click on Normalize... The settings in the Normalize dialog should not have changed since last time, but just for reference they should be set to 98% and DC Bias Adjust checked and set to 0.

Delete Silence Menu 3c) The next thing to do is to remove unneccesary gaps of silence. All speakers will leave pauses of varying length between sentences and ideas, or when turning to a Bible text, etc. When listening to the speech live, in-person, or even on video, where you can see the presenter, you don't notice this so much, but when all you have is an audio recording on a computer, especially one that's streaming over the internet, this may be distracting. Not only that, but removing unneeded silence from within a recording will reduce the size of the file you create, resulting in faster downloads for your listeners and marginally lower server costs for you. To delete silence from your recording, select Delete Silence... from the Edit menu. In the dialog Delete Silence - after that appears, set the numbers as illustrated, which differ somewhat from the default Adobe Audition settings: Define "Silence" as below -38dB for more than 1500 milliseconds, define "Audio" as above -34dB for more than 100 milliseconds, and Limit Continuous Silence to 1000 milliseconds. Once you have entered those numbers, click the "Scan for Silence Now" button, and Audition will scan through your file and pick out any sections that have more than 1.5 seconds of continuous silence and delete all the silence after the first 1.0 seconds. You will usually find between 1 and 3 minutes of silence to delete in a 30-minute speech recording. Click "OK" and the silence will be removed from your recording.

Zoom To Selection 3d) The final editing to do is trimming the start and end of the recording to make sure that the recording begins and ends where you want it to. Highlight a small portion of the beginning of the recording with your mouse, then click the "Zoom To Selection" button near the bottom-centre of the window. Once you're zoomed in, you can highlight the exact part that precedes where you want the recording to start (use the Zoom In and/or Zoom Out Zoom Out Full buttons as neccesary to view as much of the recording as you need to). Once the part you don't want is highlighted, hit the Delete key on your keyboard (or choose Delete Selection from the Edit menu). Once you have trimmed the beginning, use the Zoom Out Full button to view the entire recording, and repeat the process to trim unwanted recording from the end.
This is the end of the editing section.

4) Save & Compress
Save As 4a) Save your recording in the standard uncompressed WAV format. Select Save As... from the File menu, type a filename, navigate to where you want to save the file, and select Windows PCM (*.wav) from the drop-down list of file formats. Click "OK" and your file will be saved.

The WAV file format is uncompressed - it takes up a lot of space, but there is no loss of quality. In the next step we will take this large file (one hour of mono audio will be around 250MB) and compress it down to a much smaller file suitable for distribution over the internet. The method I will describe here will allow you to compress to either MP3 (probably the most common compressed audio format in existance right now) or Ogg Vorbis, a newer, free and better-quality-than-MP3 compression method. There are other compression standards out there, including RealAudio and WindowsMedia, but while they generally offer good speech compression, they are proprietary formats and limited availability of playback software, with no guarantee of future support (or even the ability to convert out of the format to something else) if the company developing it decides to stop doing so. That being said, if you do want to compress to a format other than MP3 or Ogg Vorbis, you may go ahead and do so from the file you just saved and skip the next section.

AudioArchive Compressor 4b) Compressing audio to really small file sizes is a somewhat tricky to get optimal sound quality from an appropriately small file, so I wrote this small program to automatically pick the best settings for each encoder, depending on the type of content you are encoding (music or speech, mono or stereo).

First, you will need to download the software: LAME is an open-source MP3 encoder that is continually being improved (see http://lame.sourceforge.net for more info on LAME). vorbis-tools, specifically the OggEnc.exe file, is the Ogg Vorbis encoder.

Once you have downloaded and saved (and unzipped if neccesary) the files, run AudioArchiveCompressor.exe. The first time you run it, you will need to specify the location for OggEnc.exe and/or lame.exe otherwise you won't be able to encode anything. After that, you can open the WAV file you saved earlier (drag & drop works too). It's optional, but highly recommended, that you enter the title, speaker/artist, date, and Scripture LAME compressing Reading (if appropriate) - this information is stored in the ID3 tag (for MP3s, Vorbis comment tag for Ogg). Track number should be used to identify the order in which multiple recordings on the same day take place (set to "1" if there was only one recording on that date). Choose which format you want to compress to (Ogg or MP3), and what Genre (speech or various types of music), and whether it's mono or stereo (only mono is allowed for speech recordings). Once the settings are correct, click the Compress button and another window will open showing the progress of the compressor. The file will be compressed to a file of the same name as the source WAV file, but with a .mp3 or .ogg extension in place of the original .wav extension.

You're now done! You may now upload the file to your website.

For more information on setting up a podcast in general, How to Start a Podcast - Ultimate Guide for Beginners by Robert Mening is a good overview of everything from subject material to audio editing.


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