DESCRIPTION:
Step 1- Drag your audio file into Audacity
Step 2- Highlight an area of static noise / background noise / hissing.
Step 3- Select EFFECT then NOISE REMOVAL then GET NOISE PROFILE
Step 4-Select OK
Step 5-Highlight the entire track by double clicking
Step 6-Select EFFECT then NOISE REMOVAL then tweak the settings to your preference (the one I have shown works almost all the time)
Step 7- Hit OK
Step 8- ENJOY !