its not excursion mp3's. its test tones. like 40hz, 50hz. you can download test tone generators and make your own cd of test tones. you can use it for "excursion" purposes. just search for test tone generator on google.
Or just go pick up something like a bass mechanik CD. They usually have test tones on them.....or atleast the Bass Mechanik I have does. It's a two disk set.