Question: In the Enhanced Voice Services (EVS) codec, what is the primary purpose of generating Gaussian noise excitation in Wideband (WB) mode?
Option 1: To introduce a tonal component for enhancing voice pitch accuracy
Option 2: To spectrally shape the innovative excitation from the algebraic codebook
Option 3: To add a second, randomly generated contribution to the innovative excitation for enhanced signal realism
Option 4: To reduce background noise in received audio signals
Explanation: The correct answer is Option 3 because, according to the EVS codec's detailed algorithmic description, Gaussian noise excitation is specifically generated and added in Wideband mode as a second contribution to the innovative excitation from the algebraic codebook. This process aims to enhance the realism of the synthesized signal by introducing randomness, following the principles outlined by the Central Limit Theorem. This addition does not primarily focus on pitch accuracy (Option 1), shaping the existing excitation (Option 2), or reducing background noise (Option 4).