Does MA 2 party consent law apply to lectures when kept completely private?

I use a livescribe pen to take notes, and it records audio and links it to what I was writing at the time. It's totally private, and only for the purpose of taking notes. I don't want to ask the whole class if it's okay for each class, because odds are, 1 in 100+ people will say no. I'd like to know whether that's legally required or not, though it is clearly good practice.