Do I need a sound Module?

Ok Here's tha problem. I have a Mo es6 and Mpc 4000.. Now I'm tryin to use the mpc as my sequencer and drum machine.. I create a drum pattern and loop it up then try an add synth sounds and different melodies I make on the motif while in overdub, But I can't seem to hear anything?
I got midi cable running in/out es6 to out/in 4000 I've been reading both manuals like crazy and I think my brain is starting to fry.. Do I need to purchase a sound module in order to hear what I record into my mpc so that I can hear them playin at tha same time
I'm new to beat makin game with hardware, so I just thought I'll ask 4 alittle help If its not to much trouble.

make sure your audio outs are connected to something. MIDI is a computer language, it DOES NOT transmit sound.

Hope that helps!

slow down a little bit. simply run your audio outs into a mixer and some monitor speakers. with a 4k and es you shuldn't need another sound-set for a while...

Yeah I have audio outs plug in....

Good lookin out!!!!!!!!!!!!

Is there anything internally I have to do with the Motif to sync it wit my mpc..???

There propably is.... check the manual!