Speaking while driving - preliminary results on spellings in the German speechdat-car database

Voice-operated devices are of particular interest in mobile environments, e.g. vehicles. They promise a natural and intuitive interface to devices and services, and they offer hands-free operation, a legal prerequisite for in-car usage in many European countries. Spelling is a common task for the operation of voice operated devices, especially under unfavorable communication conditions. This paper presents a first analysis of the error and fluency rate for 4502 utterances from the German SpeechDat-Car database. The error rate was found to be between 1.7% and 4.4% for the spelling of natural items, and between 3.6% and 7.9% for artificial letter sequences. Only 3.6% of the utterances contained hesitations. These results suggest that spelling while driving might be a suitable means of fallback interaction if specific error recovery mechanisms are implemented.