Salvaging Bad Audio: Unintelligible Speech

You first need to determine if you're a victim of Bad Recording Techniques. Poor microphone choice or bad mic placement can leave you with an audio track that's muffled or indistinct. The use of a camera-mounted microphone can result in the same symptoms. Happily, this is the easiest problem to fix, perhaps requiring only the judicious use of equalization and volume control to reduce the level of noise. Boosting frequencies around 2.5 KHz for men and 3.5 KHz for women with EQ will make the spoken word louder and will help it to cut through. Boosting frequencies around 6 KHz will increase sibilance (the "ssss" sounds in speech) and intelligibility, but it may also increase background noise and hiss, so a light touch is required.