How to normalize an audio file?

2016-10-28 05:34:04

I don't know if it's even possible to do this but here goes nothing, and please keep in mind that I know practically nothing about processing audio, all I know is how to use Goldwave to remove commercials from a radio show. I download and listen to my favorite sports radio show late at night after I come home from work. It is impossible for me to listen to it while at work. The show is heard in six different states and seems to be one of the most popular sports shows in my region, it is not a podcast, the point being, it is a professionally produced radio show and not someones basement. The show has three different hosts and all three seem to have a different volume on their microphone, because the audio file I am listening to will go from whisper soft to extremely loud, at times it seems there's a 20, if not more, increase in decibels, when a different host is talking or when someone calls in to the show. When I am able to listen to the show live, on a day off for example, the volume on their mics are identical, the high/low volume issue seems to be with the audio file the station posts on their website. I thought it might be the device I use to listen to the audio file, but it does it on the iPhone, iPad, 2 different mp3 players, PC, laptop and two different friends devices. I have dropped the audio file into Goldwave and am able to see where the file has it's high and low peaks when a different host is talking, some segments have a higher peak and others lower peaks, depending on who is talking (I call them peaks because, once again, I know nothing about audio). I have tried Goldwave, MP3Gain and Sobolsoft mp3 normalizer, but they did nothing to normalize the audio, possibly because of the three different mics being used at the studio to record the audio. All this leads to a fairly simple question, is it possible to use a program, if one exists, to equalize the volume on the audio file?

Re: How to normalize an audio file?

Reply #1 – 2016-10-28 05:52:10

Normalization won't fix this issue, since you'd need to normalize the individual mics before they're mixed into a single recording.

Instead you can try a dynamic range compressor, which will alter the audio so that the difference in loudness between sounds is reduced.  It won't be as good as if the station had correctly adjust the individual mic volumes, but it should at least help. 

Re: How to normalize an audio file?

Reply #2 – 2016-10-29 02:43:04

Goldwave has an automatic volume adjustment capability. It's in "effects"/"volume"/"auto gain".  That will take care of the problem.

Re: How to normalize an audio file?

Reply #3 – 2016-10-29 09:08:59

Such adjustments of vocal recordings are the design purpose of The Levelator
http://www.conversationsnetwork.org/levelator

Re: How to normalize an audio file?

Reply #4 – 2016-10-29 14:03:39

Confusing a normaliser for a compressor is an understandable mistake to make for a newcomer to digital audio processing. There have even been a few PC freeware releases over the years where the "Normalise" checkbox compressed rather than normalised. Of course, politely contacting the authors about this was usually replied to along the lines of, "How stupid are you? That's what normalising does!"