Two roads have crossed each other at right angles. An observer P is at a distance of 30 m from the crossing O. A car is moving towards the crossing O at a speed of 16 m/s and at the same time emitting sound wave at a frequency 192 Hz. When the car is at a distance of 40 m from the crossing, the frequency of sound received by the observer is (velocity of sound in still air = 320 m/s)