The distribution of palatal approximation

[j] in English only occurs before vowels. Many speakers will be able to form pairs with ‘beauty’ – ‘pewter’, [bj-, pj-], and ‘duty’ – ‘tutor’, [dj-, tj-], because the words that have alveolar sounds initially are followed by the sequence [ju]. For speakers of many other varieties of English (including most of the USA, but also some British varieties), the words ‘duty’, ‘tutor’ and others which start with alveolars do not have the sequence [ju], but just the vowel [u]. So the transcription would be [bj-, pj-, d-, t-] (rather than [dj-, tj-]). This feature is sometimes known as yod-dropping.