Like most bassists, I play with two fingers, index and middle. However, I have noticed that my index finger provides a clearer and "louder" tone, while the middle is more dull sounding and slightly quieter. Is this from different strength in each finger (if there is any), callouses (my index finger tip seems harder compared to the middle finger tip), or something else? Please help or provide suggestions as to how I can figure out the source of the problem and how to fix it. Thank you.