Classical conditioning is when an uncontrolled stimulus is paired with an uncontrolled stimulus to bring about a desired outcome
By associating a sound with the feeding the dog, the dog will now associate a certain sound with treats.
A good examine is the Little Albert Experiment. A baby named Albert was exposed to a white rat and initially was not scared. But when the rat was coupled with a loud scary noise, Alberts brain made the connection between the rat and fear. .
"Only by observing this condition would the results of our work be regarded as fully conclusive and as having elucidated the normal course of the phenomena." Ivan Pavlov