If a slamming door is a conditioned stimulus, then being able to distinguish between the sound of a slamming door and the sound of a heavy item being dropped would represent

If a slamming door is a conditioned stimulus, then being able to distinguish between the sound of a slamming door and the sound of a heavy item being dropped would represent stimulus discrimination. 
Stimulus discrimination is when respond and react differently to two or more similar stimulus. Slamming the door and heavy item being dropped are similar stimulus. Being able to distinguish them according their sound is reacting different to both of them , so this is a stimulus discrimination.