Compression

A compressor turns down anything above a threshold by a set ratio, then makes up the lost volume across the board. Quiet words become audible and shouted ones no longer spike, which matters on phone speakers and in noisy rooms where anything below a certain level is gone. Start gentle. A low ratio, a threshold that catches only the peaks, and a few decibels of gain reduction on your loudest lines. Overdone, it flattens delivery into a wall and pulls up room tone, breaths and keyboard clicks along with your voice. Compress after you have fixed the recording, never in place of fixing it.