In the instructions for setting up pocketsphinx, one of the dependencies is pulseaudio development package. What exactly is this? Where should I download it?
PulseAudio is a sound server library. The "development package" means that you'll need to install the development headers. For example on Ubuntu, instead of just installing the "pulseaudio" package, you instead need something like:
$ sudo apt-get install libpulse-dev
If you are developing for OSX you'll have to find a port - I don't have access to a Mac, so I can't confirm any particular one that works, but a quick Google search for "pulseaudio osx" turned up some forum posts and projects which may be a starting point.