Is there supposed to be a difference between when a bassist plucks with his index finger and when he plucks with his middle finger? My index finger has a more clear distinct tone while my middle finger have more of a "thud" type tone. I used to pop with my index finger, so I have more of a callous on my index finger than on my middle finger. I sanded most of the index callous off but I think it came back stronger. Any ways I can fix this?