A source \( (S) \) of sound has frequency \( 240 \, \text{Hz} \). When the observer \( (O) \) and the source move towards each other at a speed \( v \) with respect to the ground (as shown in Case \( 1 \) in the figure), the observer measures the frequency of the sound to be \( 288 \, \text{Hz} \). However, when the observer and the source move away from each other at the same speed \( v \) with respect to the ground (as shown in Case \( 2 \) in the figure), the observer measures the frequency of sound to be \( n \) Hz. The value of \( n \) is __________.
