As a fresher in a company you might have to face this situation: you're at a meeting and have something to say, but you aren't sure if you should since your seniors are also present. Well, according to this article in Harvard Business Review , it's important to speak up but not before judging the atmosphere of your work places.
While some companies encourage juniors to contribute to a discussion, others actively discourage such behaviour. So, learn where your company stands and make a judgement call. Keep in mind that while you may want to impress your seniors you don't want to come across as arrogant.