There will be a short amount of time before he walks out, so if the player decides to walk across the nearby lake in this time the water stream sound effect will continue to play until the player finishes speaking with the man.
In Route 30, after the player walks past a man's house he should step out and give the player an Apricorn Case. There will be a short amount of time before he walks out however, so if the player decides to walk across the nearby lake in this time the water stream sound effect will continue to play until the player finishes speaking with the man.