This study provides a more comprehensive examination of the three voiceless plosives /p, t, k/ in New Zealand English (NZE) than previous literature. More specifically, the current study explores the lenition of word-medial plosives to fricated variants, and the degree of aspiration of word-medial plosives. Our focus on different stress positions allows us to address an additional theoretical issue concerning prosodic categories in English. Two types of vowels (reduced vowels and happY vowels) are usually classified as being in unstressed syllables in English phonology. Using this impressionistic classification of vowels in unstressed syllables as a starting point, acoustic data from lenition and aspiration is analysed to examine the extent to which these two types of vowels pattern in a similar manner, as would be expected if they both occurred in unstressed syllables.