Final answer:
A listener will hear a pulsing effect called beats at a frequency of 3 Hz when two speakers play notes at 200 Hz and 197 Hz, due to the interference of the sound waves.
Step-by-step explanation:
When two speakers play notes at frequencies of 200 Hz and 197 Hz respectively, a listener will hear a phenomenon known as beats. Beats occur when two waves of slightly different frequencies interfere with one another, leading to a fluctuation in sound intensity at a frequency equal to the difference between the two original frequencies. In this case, the beat frequency would be the absolute difference between the two frequencies, which is 3 Hz. This means the amplitude of the resulting sound wave will increase and decrease (or "beat") 3 times per second, creating an audible pulsing effect. Most people can distinguish pitch differences as small as 1 Hz, so they would recognize 500.0 Hz and 501.5 Hz as being different if played sequentially.