that's exactly right rgraves
recording land line phone calls, the signal you're producing is much louder than the signal you're getting from the other person, so even though to them it sounds like your soundboard volume is just right, it probably sounds too loud to you, and then when you open the recordings in an audio editor like Adobe Audition, you can easily see in the waveform when your soundboard is much louder than the other person, which is usually the case with us
we intentionally record quietly as well, so that the stuff that's wayyyy louder like the Chinatown laugh and the screaming can be super loud, but without distorting too much on the recording
then, since we recorded so quietly, we raise the audio back up before we post the calls - an average of 10-12 dB, but NOT a simple amplification
simply amplifying all of the the sound would raise jack's voice as well - but since on almost every recording he's much louder than the other person, you have to use hard limiting, which allows you to raise the volume level of only the quiet stuff
Adobe Audition's hard limiting is a nice compression/amplification tool, with easily adjustable parameters
using their hard limiting, you set a ceiling of maybe 0.5-1.5 dB (any louder and you're in danger of popping sounds and distortion) and say, "Raise the volume of all of the audio, but only if it doesn't go louder than the ceiling." that way you get to raise the volume of the quieter stuff up near the level of the loud stuff
BUT - as rgraves said, doing so also amplifies the background noise - including the muffled laughter... and the hiss... which then necessitates that you also run noise reduction...
so it's a bit of a process
but on almost all of the calls where you hear laughter the person we're calling would have to be listening really close to hear it, but even then they probably wouldn't