These are the only ones I have. Anything more on the subject will be appreciated:
http://www.abelard.org/hear/hear.htm
If you are using headphones:
http://www.headwize.com/articles/hearing_art.htm
http://www.abelard.org/hear/hear.htm
If you are using headphones:
http://www.headwize.com/articles/hearing_art.htm