[Freeswitch-users] How to control call volume?

Hi, is there a way of controlling the volume of a call? I'm bridging calls with a JS script. Sometimes the people getting the calls complain the volume is too low. I've recorded a few of the calls and most of the times, while playing the recorded wav files, the volume of LegB (second leg of the bridge) is pretty hard to hear, even with the computer and player volume to the max (ok, it's a laptop, but even with headphones). I saw there are some volume control options for conferences, but I couldn't find anything for regular "originate calls" or bridges. I am doing transcoding, so that might help (?). Thank you very much for your help. Best, Nicolas