Rules of English Allophones

Aspiration + Voicing

Initial Stops

Voiceless stops are aspirated when they are the first word or in the initial position of a stressed syllable (p,t,k)

/s/ clusters

Voiceless stops are unaspirated after an /s/, (p,t,k)

Devoiced approximants in clusters

Approximants are partially devoiced after initial voiceless stops (w,j,r,l)

Syllable initial voiced stops and affricates

Voiced stops and affricates (b,d,g and d3) are voiceless when first syllable unless immediately preceded by a voiced sound

Syllable final obstruents

Voiced obstruents (stops, fricatives, and affricates) are partially devoiced at the end of an utterance or before a voiceless sound (b,d,g,d3,v, voiced th, z, and 3)

Voicing /h/

/H/ becomes voiced intervocalically, when it is between vowels