I was at the showing of the last series, Alan Bell also told us before to laugh loud enough and avoid any other noise that will be picked up by the microphones, he even asked the audience not to cough if possible because he doesn´t want the recording to sound "like taken in a chest clinic" or whatever he said. To be honest, I didn´t find that quite fair to the people. Nobody coughs deliberately, and what can you do about it?
It is strange, I remember laughing out loud in one particular scene more than others, but I never heard myself in the actual episode later, perhaps I wasn´t so loud after all or I was edited out.
Oh, and I liked that shrieking laugh in Penny Wassail, I always like when I can hear somebody enjoying it particularly, it´s catching.