I asked the same question earlier in the year. I was told they weren't very noisy, and to date, my six haven't been noisy at all, in fact, they are very quiet. My hens and ducks make more noise than the turkeys. Perhaps in the spring with mating season they will make more noise. I have 2 males and 4 hens.
They make maybe as much noise as chickens they just sound like turkeys..really though mine make noise at things that are out of the ordinary which to me is a good thing they talk to me when I'm bringing them treats or when they think I should be bringing them treats and I love making them gobble. One neighbor thought they would be noisy but the turkeys have won him over when he walks his dog he now brings them treats....the other neighbor who was scared of them at first brings them apples and was all worried that the Jakes were trying to kill each other wrestling over the girls attentions. To me roosters are way louder than any flock of turkeys and turkeys impress people when they strut their stuff......I don't think any of my neighbors are coming over for turkey dinners any more either they never knew how turkeys were so social ....can't believe I'm going to eat them.
I agree with Lotsapaints. They make about as much noise as chickens, but they are turkey noises. Once in a while the boys will raise a ruckus but most of the time they're fairly quiet.
Personally I think they are quite loud, but I work nights and sleep during the day when they "get lost" and start calling to each other. Also, at least my Tom's gobble all the time if I am outside, maybe its just them but it can be quite annoying on a peaceful summer evening when you are trying to enjoy the outdoors. They make noise more frequently than my guineas or chickens, but without question the guineas are more loud when they alert (it just doesn't happen very often, unless one gets lost...). Personally, and maybe its just me or my turkeys they are often not worth the cost of food or huge piles of poop. I find the chickens and guineas more interesting...
The girls will chatter away to each other while they're grazing. It's just a nice soft almost cooing sound that they make. If someone strays away or they get frightened or see something they need to explore (I love this comment someone made about turkeys "that looks dangerous-let's go check it out")then they will make a sort of shrill "wheat, wheat" noise. The boys on the other hand will gobble at the drop of the hat....literally. On a purely decibel level it's still not as loud as say....a guinea or barking dog or screaming kid but my husband at least finds it annoying.