Final answer:
The average person can typically tell the difference in frequency between a 2002-Hz sound and a 1999-Hz sound without playing them simultaneously.
Step-by-step explanation:
Most of us have excellent relative pitch and can distinguish between two sounds if their frequencies differ by 0.3% or more. Therefore, the average person can typically tell that a 2002-Hz sound has a different frequency than a 1999-Hz sound without playing them simultaneously. Even a difference of 1 Hz in frequency can be noticeable to our ears.