I realized the easy solution is to fix the ‘volume’ of the MP3 file using Audacity. Audacity is a free audio editor and recorder that works in Windows, Mac OS X, GNU/Linux and other operating systems. According to the web site, you can use Audacity to:
- Record live audio.
- Convert tapes and records into digital recordings or CDs.
- Edit Ogg Vorbis, MP3, WAV or AIFF sound files.
- Cut, copy, splice or mix sounds together.
- Change the speed or pitch of a recording.
- And more! See the complete list of features.
Now, I just need to boost the volume and Audacity makes it an easy task. I created a ‘chain’ (Audacity’s version of a batch file) that converts the file to mono (why not) then amplifies it and finally saves the file.. These ‘chains’ can be applied to a single file or to a whole folder of files, making batch conversion quite easy for each book.
p> You can see from the two images on the left that the original sound file’s amplitude was way low. (No wonder I could barely hear it.) Below it is the same file after it has been amplified using Audacity. I am sure if I was amplifying music files I would have to be more careful but for voice I have found that I can even amplify the volume more without any noticeable degradation. Now I can play my audiobooks and not have to strain to hear them.