Greyhounds generally tend to not be barkers, but many who do learn from being around other dogs who do bark I've had one who barked, he was very territorial and protective of me, also not really typical greyhound traits. His bark was very scary, I felt very safe with him around. The rest of my greys, not so much although I have found some people wary of my two black girls, I guess they just see a big black dog.
If you work with a group, explain your lifestyle and what you are looking for, I am sure you could find a grey who would suit.