Speech recognition systems face challenges related to accuracy, responsiveness, performance, reliability, and fault tolerance. Accuracy can be impacted by audio quality and talk-over problems, which require solutions like echo cancellation and barge-in. Responsiveness requires delayed recognition to avoid processing before resources are ready. Performance issues stem from large grammar sizes and collisions, addressed through optimization and special tokens. Reliability over long periods requires automated testing and drive tests. Fault tolerance involves modular system design that allows restarting components without affecting others.