A given test consonant should occur in a short sentence in 'strong' and possibly other positions. The following test consonants should occur in a sentence:
- all single(ton) pressure consonants
- a nasal consonant
- others as required
English sentences: Revised GOS.SP.ASS sentences (Sell, Harding, Grunwell, 1998).
Full reference available here
With regard to vowels, the following is suggested:
vowel height should be taken into consideration when deciding on the phonetic content of the sentences