Lexical Coverage of Spoken Discourse

The Schonell et al. (1956) study of Australian oral English found that 2,000 word families provided around 99 per cent lexical coverage of spoken discourse. Based on this, scholars have accepted that around 2,000 word families provide the lexical resources to engage in everyday spoken English discourse. This study analysed a modern spoken corpus (the CANCODE corpus) and found that 2,000 word families made up less than 95 per cent coverage. A second analysis was performed on the CANCODE and the spoken component of the British National Corpus, which found that around 5,000 individual words were required to achieve about a 96 per cent coverage figure. These results suggest that more vocabulary is necessary in order to engage in everyday spoken discourse than was previously thought. The implication is that a greater emphasis on vocabulary development is necessary as part of oral/aural improvement.