I was hoping someone could suggest a good CD, DVD, or DVD-A that I could use for a science project my daughter is putting together. We are looking for a disc that would have test tones im steps (ie 80hz, 70hz, 60hz, ect down to at least 20hz or lower). I have some but they are all sweeps and we were looking for some software with steps. Any suggestions would be greatly appreciated. We were hoping to knock this out over Christmas vacation.