Your Greyhound is always communicating with you. Human communication is mostly verbal, and while some Greyhound communication is vocalizing, much of it is body language. In any case, you will want to pay attention to the whole dog: body language gives the vocalization context. Here is some inside information that may help you understand your hound better.
We often think that communicating with our dogs means we talk to them, but in fact we can recognize what our dog is saying - even what he's thinking - just by learning our Greyhound’s body language. We need “listen” with our eyes to understand what they are telling us, and in the same way, we need to be conscious of our body language to be sure we are not inadvertently communicating something that we don’t mean!