Though it is difficult to change one's core character and behaviour, one should train to adapt and act or react as per situational needs.
Honesty is the best policy.
If we have a large sum of money, we would obviously be silent and not broadcast to everyone. If we were to have some important information that would benefit all, we should be willing to share it with others.
Being a silent spectators helps in very few situations in life. We need to be a keen listener with the maturity to know when to talk and when not to talk. A responsible conservation is better than silence and far better than being a blabbermouth. There are some scenarios wherein whatever we say would be misunderstood or would be inappropriate, in such circumstances, it would be wiser to be quite and reserve explanations for another day.
We often remain silent while offering prayers to the God though in other forms of worship even loud music is used e.g. during 'kirtan' or 'Sankirtan'.
Listening to others is considered one of the most sincere form of paying respect to elders or seniors.
Let us encourage each other in sharing knowledge.
Alternatively this needs to be different on various occasions & this should be the appropriate one or balanced mode. In a court while defying a victim if we remain silent & observing throughout session will certainly wouldn't give you the good image & at the same time not able to defend in an appropriate way. In a different scenario & assuming that we are faced by a rough & we started an argument then might be the possibility that later on we feel inappropriate for behaving so.
In a nut shell, speak up when required & when it is appropriate & fits you which can't be predetermined.
Silent is good but not in all conditions when you know something is wrong. If a person keeping silent even knowing the fact, it simply means that he has the sycophancy character. Who may try to show himself/herself a saint in open but inside having evil mindset. So, such kind of silent will do no good in any kind of society or relationship.
In general, it is believed that listening is a better trait than talking. There is an old saying that ' Speech is silver but silence is gold'.
Knowledge is power.