Step 1: Understanding the Concept
For \(y=a\sin(\omega t)\), the frequency is \(f=\frac{\omega}{2\pi}\). Beats occur at the difference of the two frequencies.
Step 2: Calculation
\(f_{1}=\frac{600\pi}{2\pi}=300\ \text{Hz}\) and \(f_{2}=\frac{608\pi}{2\pi}=304\ \text{Hz}\), so the beat frequency is \(4\) beats/s. The maximum amplitude is \(4+5=9\) and the minimum is \(5-4=1\).
Step 3: Compare the options
Intensity is proportional to amplitude squared, so \(\frac{I_{max}}{I_{min}}=\frac{81}{1}\). So the answer is 4 beats/s with ratio \(81:1\).
Final Answer:
The observer hears 4 beats/s with an intensity ratio of \(81:1\).
\[ \boxed{\text{(D) }\text{4 beats/s with intensity ratio 81:1 between waxing and waning}} \]