The answer to 'why is my sink making gurgling noise' is that a gurgling sound in the sink is typically caused by a blockage or obstruction in the drain pipe. This can happen when debris, hair, or other materials build up and restrict the flow of water, causing air bubbles to get trapped and create the gurgling sound.
Some common causes of a gurgling sink include a clogged drain, a problem with the vent pipe, or an issue with the P-trap under the sink. The gurgling may also be accompanied by slow draining water, foul odors, or even water backing up in the sink. In most cases, the issue can be resolved with some basic DIY troubleshooting and plumbing maintenance. However, if the problem persists or you're not comfortable tackling it yourself, it's best to call in a professional plumber to diagnose and fix the issue.