Telephone channel normalization for automatic speech recognition

The authors describe typical variabilities that are found in telephone channels and show how these variabilities impact automatic speech recognition (ASR)-system performance. They describe an algorithm, based on spectral subtraction, that compensates for these types of degradations. This algorithm can be utilized at the beginning of ASR interactions to estimate a compensation vector that improves recognition performance during the rest of the interaction. They have tested and validated the algorithm in terms of recognition performance and speed of convergence