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AUDIO RECORDING AND EDITING
FOR THE WEB AND IPODS

Dr. Richard L. Bowman, Director
Academic Computing, Bridgewater College, Bridgewater, VA, USA 22812

I. Introduction

While Apple's iPod and iTunes (the software handling the uploading of files to an iPod) have spurred a major upswing of interest in retrieving audio file from the Internet, professors might consider creating and using audio files simply as a means to giving students another method of learning content whether they have a iPod or not. The files described below can be listened to directly from a web page using either QuickTime Player or Windows Media Player, or they may be downloaded and then uploaded to an iPod or other mp3 player.

Note: What is described in this tutorial is how to record audio files, do some minor editing, and post them to the web. iPod users may then download these files and use iTunes to upload them to their iPods as "music" files. Owners of other brands of mp3 players may follow the directions for their devices. (Setting up an RSS feed for students to subscribe to these audio files in a topic beyond the scope of this tutorial and is not necessary for the effective use of audio files for class purposes.)

II. Look at a Sample Presentation

This sample audio file is of me explaining the physics behind flywheels [257 KB]. (There is also an associated video [843 KB].

III. Read a Word about Audio File Formats

While there are a multitude of file formats for audio data, there are only a few main ones. (In fact there are 321 audio file formats listed and described at FileInfo.com.) Below are just a few of the main types.

  File Extension   Brief Description of Format
  aiff   Audio Interchange File Format - am older file format developed by Apple for storing uncompressed audio data.
  avi   Audio Video Interleave - an older file format that may store compressed audio or video file format.
  cda   CD Audio - format for audio files on CD-ROMs such as music CDs and thus cannot be played on iPods or mp3 players.
  midi   Musical Instrument Digital Interface - this file format was originally used to store music generated by MIDI devices connected to computers; cannot be played on iPods or mp3 players.
  mp3   Moving Picture Exerts Group standards file format - comes in other versions also, but mp3 is the most popular audio file format in these standards.
  wav   Waveform Audio - the old Microsoft format that usually stores uncompressed audio data.
  wma   Windows Media Audio - the current standard file type used by Microsoft; it uses a fairly robust compression algorithm resulting in small files appropriate for posting on the Internet; cannot be played on iPods or mp3 players.
  • So which file type should you use to record lectures or extra material? As noted above iPods and mp3 players can play most of these formats except for cda and midi. However, to ensure that essentially everyone can listen to your voice, my suggestion is to use only the mp3 format (the wma format would be a reasonable choice, too).
  • The file format is given by its extension in a Windows system. To be able to view the file extensions on your Windows computer, open up My Computer (or any file folder) and click on the Tools menu in Windows XP and select the Folder Options. In Windows Vista, click on the Organize menu and select Folder and Search Options. In the new window that opens, click on the View tab and scroll down to the line that begins "Hide extensions...." Make certain that there is no check in that box and then close the window. All file extensions should now be visible at the end of the file name.  

Note: More information about audio file formats may be found at the following sites.

Note: The various players can be downloaded from the following sites.

IV. Check out Your Microphone

  microphone connected to a computer   Contact the IT Center to request a microphone for your office computer. You should also request a set of speakers, if none are presently attached to your computer.

If you need a microphone for your home computer and are planning on doing only voice recording, there is no need to purchase a high quality microphone. In fact a simple microphone such as pictured at left can be obtained for under $30 and works great.

To connect the microphone, move to the back of your computer and locate the sound card with a jack for a microphone and plug the microphone into the jack. Presto! All is ready. Position the microphone such that you are talking fairly directly into it.

Then make a trial recording with Windows built-in sound recorder. (See the next section) If it sounds well in play back, then you are ready to go. If there is distortion, it may be for any of the following reasons.

  • While you do need to be close to the mike, being too close (closer than six inches) may make a bad recording with pops and distortion.
  • The recording sound level is too high. Check this by going to the Control Panel and then and then the Sound page. Check the recording level of the microphone. Make sure it is around 50%.
  • The microphone and your sound card in your computer are not matched. From the device manager discover what sound card is installed and then make certain that the microphone and the sound card will work together. (With current computers, this is usually not a problem.)

V. Locate and/or Install a Sound Recorder

1. Windows Sound Recorder

Windows come with a built-in sound recorder. It is very basic, but it reproduces voice sounds very adequately.

In Windows XP the sounds recorder is limited to recording only one minute of audio and outputs by default in wav format. There are a few items that may be changed and a few effects that might be interesting to explore. (See the next section for details on how to access the properties that may be changed in this program.) If you want to see how a particular microphone works or want to begin exploring audio recordings, this sound recorder will do the job. It may be accessed by clicking on All Programs in the Start Menu and then on Accessories. Finally choose the Entertainment folder and click on Sound Recorder. It will show up looking like the image below.

Windows XP Sound Recorder

Windows Vista has a sound recorder that can record longer files and it saves the audio files as wma files. Thus this is a much better option to use for many basic situations in which faculty would need a recorder than its predecessor in Windows XP. However, it has few options to change. (See the next section for the few that may be changed.) It can be located by going to the Start button and then All Programs and finally Accessories. There click on Sound Recorder. There is a Start Recording button and a volume level display next to an elapsed time clock. After recording, pressing the Stop Recording button brings up the usual Save As dialogue box.

Windows Vista Sound Recorder

For more advanced recordings, use one of the many audio recording and editing programs that are available for purchase or as freeware. Three of these are described below.

2. Free Sound Recorder

A somewhat more advanced program may be accessed at http://www.freesoundrecorder.net/ . Download the latest program from cnet (a reliable source for free software), save the file to your computer, and then double-click on the file icon where you have saved it to begin the installation process. (A free-to-try sound editor will also be installed, but this can be ignored and its icon deleted from the desktop.)

When the program starts it should look something like the picture below, after closing the Device drop-down box below the main program graphic.

Free Sound Recorder

Note: While you are at the Free Sound Recorder web site, download and save the Overview file from its link at the bottom of the page. It is a very good tutorial on many aspects of working with audio recording on a Windows computer.

3. Audacity

For more flexibility, install and use the open-source recorder and editor, Audacity. It may be accessed at http://audacity.sourceforge.net/ . Generally the best advice is to download the latest version and not a beta version, which may still have bugs in it. Save the file to your computer and then double-click on the file icon to begin the installation process.

Audacity

To save an mp3-format recorded file, Audacity needs the file, “lame_enc.dll”. Follow these instructions for locating and installing this file

  • Get it at http://www.dll-files.com/dllindex/dll-files.shtml?lame_enc . Be careful to scroll down the page a ways to locate the correct link to download lame_enc.dll. When you actually get the file saved, it will be a zipped archive file.
  • Unzip the files, then find the “lame_enc.dll” file and copy it into the Audacity folder on the C:/ProgramFiles/.
  • Finally, in Audacity go to Edit/Preferences/File Formats and then “MP3 Export Setup” and click on “Find Library.” In the resulting window, browse to the location in C:/ProgramFiles/ where the lame_enc.dll file is located.

VI. Getting Ready to Record an Audio File

Since normal voice recordings do not require a lot of high-fidelity (quality), in the recorder you have installed select a recording speed that is on the order of 28 kbps and a mono sound (not stereo). Each recorder is somewhat different in where these options are located, but try looking for Settings, Preferences, or Options. Below are the procedures for the three porgams discussed here.

  • Windows XP Sound Recorder: While this program may be used "straight-out-of-the-box," it does have more flexibility than it appears to at a first glance.  To access these items, select Properties from the File menu of the Sound Recorder. Of most concern will be the ability to record audio files in mp3 format. Click on the drop-down menu in the "Format Conversion" section and choose "Recording Formats." Then click on the "Convert Now" button. In the new window choose the format "MPEG Layer 3" and change the Attributes to "18 kilobits/s, 11,025 Hz, Mono" or some such. This will make the resulting file smaller.
     
  • Windows Vista Sound Recorder: While this built-in sound recorder is ready to record "straight-out-of-the-box," the user may make a few adjustments by opening the Control Panel (from the Start button on the Windows taskbar) and selecting "Hardware and Sound." From there select "Manage audio devices" under the Sound heading. In the resulting window select the Recording tab and then make certain that one or more microphones has a green checkmark by its icon. Double-click on the icon, and a new window with some items that may be changed about how the microphone will record sounds will show up. What particular items you see will depend upon your computer's sound card. Experiment if you are so inclined but don't change drivers unless there is a problem. 
  • Free Sound Recorder: Press the Select Folders button and locate the folder into which the output file will be saved. Then press the Settings button and select the General Settings tab, and make sure the Output File Type is set to Mp3 File. Then select the Output File Settings tab. Select the Perset Quality and move the slider to the Low Quality end. The display should read "MPEG 2.5, Layer 3, 16 kbps, Mono." Say OK, and you are ready to begin recording. 
     
  • Audacity: As done above to add the lame file, from the Edit menu select Preferences. Then click on the File Formats tab, and in the “MP3 Export Setup” set the Bit Rate to 16. Say OK and you are ready to begin recording.

Note: The size of file that results from the differing bit rates approximately depends upon the factor that one speed is larger or smaller than another rate. For example, recording at 24 kbps makes a file that is about 5 times smaller than if the same message was recorded at 128 kbps.

VII. Recording and Saving an Audio File

Recording and saving an audio file is fairly straight-forward in each program, but there are some significant differences.

1. Windows Sound Recorder

  • To begin recording, press the button with the red ball on it. (In Windows Vista it will also have the text "Start Recording" on it.)
     
  • Stop the recording by pressing the same button (now with a black or other dark-colored square on it), and the file can be saved.

2. Free Sound Recorder

  • To begin recording, press the button with the red circle on it. A box for entering the file name will pop up. Notice in the bottom of this window is the folder in which this file will be saved. To change that folder, Cancel and go to the Settings button. Find the Output Directory section of the General Settings tab and Change this value. After entering the file name, recording will begin automatically.
     
  • Press the Stop button (with a white square on it). The file will be automatically saved.

3. Audacity

  • To begin recording, press the Record button (with the red circle on it) just below the menu identifiers and begin talking.
     
  • Stop the file by pressing the Stop button (with the grayed yellow square on it).
     
  • Save the file by selecting "Export As MP3..." from the File menu. Adjust the name of the file as appropriate and then Save the file. A dialog box will show up allowing the user to edit various items in the tag for the audio file. The Title shold be descriptive of the content. The Artist is you name. The Album might well be a course name and general content, for example, PHYS 110-Keplers 1st Law. Type in Track 1 and any comment up to 30 characters in length. This info will show up on the display of any iPod playing the file.

VIII. Reduce the Size of Your Audio File

In many of the sections already introduced in this tutorial, hints have been given about how to ensure that the size of the resulting audio file will be small enough for use on the web or in Moodle while retaining reasonable quality.

However, what can be done to a file that was recorded and is larger than desired? (Such a file could be several megabytes (MB) but only one to three minutes in playing length.)  There are several software packages that may accomplish such a compression, but one of the simplest I have found that is freeware is Free Mp3 Wma Converter. At the writing of this tutorial, I am using version 1.8 of this program on my home computer.

Free Mp3 Wma Converter may be obtained by searching for it at www.downloads.com . When installing Free Mp3 Wma Converter, you will see a dialogue box with four items checked for installation. Leave the checks by the Converter and the installation of Wma runtime files, but remove the checks by the other two items.

The highest saving in size is from the conversion between a high-quality mp3 recording to a wma-format file. However, even reducing the qualtiy of the mp3 file can make a significant size difference. To do this add the mp3 file to the list of files at the top of the program window and then select the output format to also be mp3 with a 16,000 Hz sampling rate (the main skin incorrectly lists this as 16,000 kHz but the settings window has it correct), mono, and a bit rate of 32 (or even 24) kbit (this is really kb/s).

As an example, I converted a CD-quality mp3 file (44 kHz stereo) to one of lower quality (16 kHz mono) and the file went from 2360 KB to 614 KB--almost a decrease by 1/4. When I saved the original file as a wma (16 kHz mono), the file size went down to 326 KB--almost 1/8 the size of the original file. Remember, iPods and other mp3 players can also play wma-formatted files. So going to a wma file is safe as far as user-friendliness is concerned.

IX. Publish Your Audio Segment On The Web

After saving your audio file, locate it and double click on it to open it in your default player. If it sounds OK, then it can be copied to your web directory.

Remember that this file cannot be found by students in a course unless it has been added to the appropriate location.

  • To make the file accessible through a link on a web page, copy the file to the appropriate web folder and insert a link to it on the appropriate web page.
  • To use this file as a resource in an assignment in Moodle or some other course management system, import it into the course in Moodle and then link it to an assignment or resouce.

Appendix: Resources

In addition to this tutorial, the reader will probably find several other resources helpful.

A. Help Menus

All of the above programs have some associated help files available through their Help menus. Browse all of them, even if you are only going to use one of them. Some of their information is very generic and very useful for making any sound recording.

B. Other Tutorials through Academic Computing at Bridgewater College

C. Other Resources


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Bridgewater College Home Page 2007-09, Richard L. Bowman
Last modified: 9-Aug-09; by R. Bowman,
rbowman@bridgewater.edu