The answer to 'drain trap making noise' is that a noisy drain trap is usually caused by a buildup of debris or a problem with the trap's water seal. This can lead to gurgling, whistling, or other noises coming from the drain.
Some common causes include a clogged drain, a dry trap, or a problem with the plumbing vent system. In most cases, the solution is to clean out the trap or address the underlying issue. However, if the problem persists or you're unsure of the cause, it's best to call a professional plumber to diagnose and fix the issue.