If Adam and Eve “heard the voice of the Lord God” in Gen 3:8, can we say what God was saying, or what sounds he was uttering?

We do not know, and this is not explicitly stated. With the charming scene of God strolling through paradise in the cool of the day, one might imagine God to be humming or singing. But there is some small reason to think otherwise, because Adam and Eve hid—implying that they thought God was looking for them—and in the next verse, the voice of God is reported as saying “Where art thou?”