Question: In the context of the EVS codec's Forward Error Correction (FEC) mechanism, what is the primary reason for using a distinct signal classification approach compared to the one used for selecting UC and VC frames?
Option 1: To reduce computational complexity in noisy channel conditions.
Option 2: Because the ideal concealment strategy differs between quasi-stationary speech segments and those with rapidly changing characteristics.
Option 3: To align with the coding mode determination process for consistency across the codec.
Option 4: Due to the incompatibility of UC/VC frame selection algorithms with FEC's error resilience goals.
Explanation: The correct answer, Option 2, highlights the key reason for the differentiated approach: the varying concealment strategies needed for different types of speech segments. This distinction is crucial for optimizing the codec's performance in noisy channels, as quasi-stationary and non-stationary speech segments require different handling to maintain audio quality. This question assesses understanding of telecom concepts related to error correction, signal processing, and adaptive coding strategies in wireless communications (e.g., 5G, RAN).