I'm planning to use the language lab OWL Oohoo plugin (https://moodle.org/plugins/mod_languagelab) for my english language lab. Could you please suggest the hardware needed to run it smoothly for up to 30 users in intranet ? If possible, please give technical details.
Almost certainly not. I assume you mean 30 'concurrent' users in a class at the same time? That's not a huge number as long as the system is set up properly.
This sort of question is asked all the time in this forum. You'd do well to have a look through some of the threads to get ideas. Unfortunately, everybody's situation is slightly different and these differences can make affect performance significantly.
Best advice is, read this - Performance_recommendations. Then set up a pilot on whatever hardware you have handy and see how you get on. Obviously (I hope) monitor the system and extrapolate.
I can help you with that even less. Although, is this still really a Moodle question? You may well get a more useful answer from whoever supports the streaming software.
I had a small home server setup when I tried to use OWL Language Lab in my computer lab with a maximum of 16 students at a time. I had one server at home running both Moodle and Red5 streaming server. I could handle all 16 students starting a quiz at the same time, but could only handle 4 students at a time in the OWL language lab. My problem was due to the small bandwidth, only one and a half million bits per second, coming out from my home server. I hoped to move the streaming server to a computer right in my lab, but other projects kept me too busy to try it out.