ASR in portable wireless devices

This paper discusses the applicability and role of automatic speech recognition in portable wireless devices. Due to the author´s background, the viewpoints are somewhat biased to mobile telephones, but many of the aspects are nevertheless common for other portable devices as well. While still dominated by the speaker-dependent technology, there are today signs that also in wireless devices, there are ASR trends towards speaker-independent systems. As these modern communication devices are usually intended for mass markets, the paper reviews the ASR areas that are relevant for speech recognition on low cost embedded systems. In particular, multilingual ASR, low complexity ASR algorithms and their implementation, and acoustic model adaptation techniques play a key role in enabling cost effective realization of ASR systems. Low complexity and advanced noise robust ASR algorithms are sometimes conflicting concepts. The paper also briefly reviews some of the most important noise robust ASR techniques that are well suited for embedded systems.