Question
Two sirens A and B are at a certain distance apart and sounding at same frequency. When a person standing between two trains starts running along the right bisector of AB, he does not hear any beat. Explain why.
Solution
The apparent frequency of sound observed by him from both the sources will be same, when the person starts running along the right bisector of AB.
That is why the person does not hear any echo.
That is why the person does not hear any echo.