Question: In EVS (Enhanced Voice Services) codec, what is the primary purpose of transmitting energy information using 5 bits, particularly in the context of frame erasure concealment?
Option 1: To enhance speech quality by boosting signal energy in voiced segments.
Option 2: To minimize energy discontinuities at the decoder by scaling the synthesized signal to match energies between the last erased frame and the first non-erased recovery frame.
Option 3: To reduce bitrate by averaging energy levels across consecutive frames.
Option 4: To improve prediction accuracy in VC (Voice Coding) and GC (Generic Coding) modes.
Explanation: The correct answer highlights the key objective of transmitting energy information: to ensure a smooth transition in signal energy when switching from an erased frame to a non-erased one, thus enhancing the perceptual quality of the synthesized sound. This is crucial for maintaining consistent audio levels and preventing abrupt changes.