The time it takes for light to reach people's eyes =60 divided by 300000000 seconds (extremely short time).

It takes time for sound to reach people's ears =60 divided by 240 seconds.

Then subtract the two times to get the time interval.

Because the light transmission time is very short and close to zero, it can be ignored. So use the time when the sound reaches the ear as the time interval.

The formula t=s/v2-s/v 1.

Time interval t, s is the distance, v2 is the speed of sound, and V 1 is the speed of light.