in reply to
reading sound input
Which operating system are you on? For *NIX there is a device handle called /dev/dsp that you can read data from, the module Audio::DSP allows an easier interface to setting that up, on windows there's something called Win32::SoundRec. Once you have the data there is another module called PDL::Audio that should allow for manipulation and writing of the file.
What do you want to do with the sound? For real time recording/manipulation/output perl may not be the best tool for the job, especially if you don't have much experience with perl. Do you have experience with manipulation of sound files?