Something is partially plugged I would think. The gurgling is the sound of air being pushed back up through the water. Since it's probably partially plugged a plunger probably won't clean it out. I would start by taking the trap apart to be sure it's clean. If it is then it's a matter of getting to wherever the clog is in the pipe and cleaning it out.
It is strange that it started happening right after he changed the faucet and trap. But, changing those two shouldn't have caused the problem. Anyway, that's my opinion. Any thoughts from others?

The trap was replaced merely because it was part of my plumbers normal routine when they install a new faucet.

If you cover the drain opening with your hand while the gurgling is occuring, does the sound deaden? Or is the sound coming from the faucet spout?

The sound is definitley not coming from the faucet spout. When I cover the drain opening with my hand, it still gurgles but the sound is duller and it can be heard more in the pipes inder the sink than right at the sink level. I did contact my plumber again about this issue and he said that the only solution he can come up with was to cut a hole in the back of the vanity and add some kind of device (the name escapes me) to the pipe to help with the air issue. It sounds costly. There must be something easier. This problem did not exist until they remodeled the bathroom.

By the way, just talked to my plumber again. What they are suggesting is installing a "studor vent?" behind the vanity. Can anyone tell me what that is?

It sounds to me like there's some obstruction in the vent leading off of that drain. The gurgling sound may not have been noticeable before because the old trap had built-up crud in it that either muffled the sound or slowed the escape of air so that you didn't hear a gurgle.

Is this bathroom on the upper floor of your house, or in a single story house? If so, look up on your roof. If you see the vent pipe extending through the roof directly above the sink area in your bathroom, check it for any sort of visible clog that would prevent it from working properly. If you can't see anything, then you might try snaking the vent line to clear any any obstruction further down the line. Short lengths of manual plumbing snake are available at your local home center or hardware store.

If you don't see a vent pipe protruding through the roof in the general area above the sink, your house may have vent lines that are connected to a central vent stack (more common on older or higher-end construction), or if the bathroom was added by a previous owner, it's possible that it wasn't properly vented at all.

Studor vents aren't approved by the plumbing codes in all localities, or for all applications, but this type of vent is a possible solution if your sink isn't already properly vented. Your plumber should certainly know if a Studor vent is proper solution and complies with local plumbing codes.

If there is a roof vent, though -- check it for obstructions first. Clearing a vent obstruction would be the easiest and cheapest fix.

Exceelent advice. Thanks. To answer your questions.. Yes, the bathroom is located on the second floor of my home. Yes, there is a copper looking vent pipe extending out of my roof. I don't think it is directly above the bathroom but I would venture a guess that is located somewhat close to the bathroom (even though I have second bathroom on that floor that does not have any gurgling). When my house was being built 12 years ago, I was told that vent was because I had a dishwasher. Hmm. Your suggestion is the easiest and cheapest and I need to ask the plumber if they already explored this idea. He might have because he did ask to go into my attic the other day. Also, why is it thatwe are only getting the gurgling from the master bath? I'm sure the other bathroom must be vented into that roof pipe as well. If I do nothing - will this go away in time? Will I hurt anything if i do nothing?

By all means, ask your plumber about checking the vent line.

I thought about this after posting above, and my gut feeling is that your old trap may have been gunked up a bit, and it was either muffling the gurgling noise you're now hearing, or the new trap is perhaps made of a different material, or isn't as deep as the old one, so that it tends to siphon more readily. Anyway, if the drain is clearing as it should and you're not getting any noxious odors coming from that drain, then I don't think you're hurting anything. Over time, it may accumulate a little gunk, too....and the sound will moderate, or you'll get used to it and not notice it any longer.

In the meantime, do get your plumber to check the vent for obstructions. If you do notice odors coming from the drain and it continues to gurgle, that's a sure sign of a venting problem and would indicate that the trap is being siphoned. If the water in the trap gets siphoned out, gas or odors from the sewer line could pass into your living space -- a potentially unhealthy situation.

Thank you again. I will ask the plumber to check the vent before we go the studor vent route. Is the best way to check to go up on the roof? Who knows, maybe something got in there like a leave or something, althoughh the pipe outside appears to be fairly small diameter.

There is definitely no odor at all and the sink is draining better than it ever did. Its just that gurgling sound is loud and driving us nuts!. Since it seems that it can't hurt us (unless we have an odor), I may just leave it alone. Thanks to your help, I have some ideas now. The plumber is going to still give me an estimate for the studor vent as well.