Smooth and Enhance

Smoothing has the effect of removing noise (audio interference that sounds like static). To smooth your file, select Process | Smooth/Enhance.

Try smoothing with a setting between -3 and -5, aiming at the best reduction of noise with little or no change in the overall volume. If the original file sounded muffled rather than noisy, adjusting the value up toward Enhance can be helpful.

Listen to the sample sound after Smooth/Enhance filter