- 1. Download and install Audacity Beta 1.3 along with the optional Lame MP3 encoder. The other extra plugins can be downloaded and installed if desired. http://audacity.sourceforge.net/download/
2. Clean the tape heads with a Q-tip and alcohol. Rubbing alcohol will work fine. Wait a minute or so for the head to dry. Demagnetize the head if a demagnetizer is available (tape player must be off when used). Repeat every 20 hours or so.
3. Record the tapes. Audacity can be used for this. The default settings (stereo, 44.1Khz) is fine. The default sample format could be set to 16 bit since standard cassette tape only has about a 12 bit resolution (60dB). The extra resolution is only not useful and only increases the file size.
4. Trim the front and back to leave a lead-in and trail-out of about 1/2 second. You can zoom in and out using the entries in the 'View' menu. Sliders at the bottom of the application window allow moving in the audio waveform. Select the audio to trim by left clicking and dragging the mouse. Delete using menu "Edit:Delete".
5. Select the entire remaining audio by using the keyboard combination Ctrl+a or by clicking in the panel to the left of the audio waveforms. Both channel waveforms will highlight.
6. Convert to mono by using the menu "Tracks:Stereo Track to Mono". A single highlighted mono track will be displayed.
7. Set the Project Rate in the lower left corner to 22050. This will cause a re-sampling when the file is exported in later steps.
8. Normalize the amplitude to -2dB by selecting "Effect:Normalize..." and setting to -2.0. Both check boxes should be set to true. A value of -2.0 leaves some head room for later filtering if needed.
9. Save the file in a lossless compressed FLAC format: "File:Export" Select "FLAC files" as the type. Use a name that matches the format used on the FSI site. Click the "Save" button. Keep this file as a backup.
10. An "Edit Metadata" screen is displayed. Fill in using the standard values used on the FSI site. Example: Artist Name = Foreign Service Institute. Track Title = Yoruba Basic Course Tape 01 Side A. Album Title = Yoruba Basic Course. Track Number = 1. Year = 1963. Genre = Speech. You can save the values as a default and then edit the values for later tapes. Click the "OK" button. A file with a ".flac" extension is created. Audacity can open these compressed files. There are also free players. I use the "foobar2000 audio player".
11. Export an MP3 version:"File:Export". Select "MP3 files" as the type. Click the "Options" button and select "Bit Rate Node" = Average. "Quality" = 56kps. Don't worry about the "Stereo" selection, it will be ignored on mono files. This will create a variable bit rate MP3 file. 56kps is pretty much lossless for voice. Keep the current meta data when the Edit Metadata panel appears.
If you want, you can try applying different filters between steps 10 and 11 to reduce the hiss noise. On the other hand by providing a high-quality unfiltered file, others more expert than you or me can experiment to come up with a good noise removal method.