The answer to 'drain trap making gurgling noise' is that a gurgling drain trap is typically caused by a blockage or obstruction in the drain line. This can allow air to be drawn back up through the drain, causing the gurgling sound.
Some common causes include buildup of hair, food, or other debris in the trap or drain line. It can also be caused by a vent pipe problem that is allowing air to be drawn back through the drain. In some cases, a gurgling trap may indicate a more serious issue like a broken or cracked drain pipe.