Error Type	Definition
Distortion	An attempt at the target phoneme that did not cross the phoneme boundary, produced with perceptible place, timing, manner, or voice deviation from accurate production
Distorted substitution	A production that not only crossed phoneme boundaries of the target phoneme, but was also distorted (van der Merwe, 2009)
Distorted addition	An inserted nontarget phoneme that is distorted
Sequential substitution	Inclusion of phonemic perseveration, anticipation, and transposition errors; these errors are influenced by the context in which the word is produced
Nonsequential substitution	Phonemic errors influenced by factors outside the target word (Mackay & James, 2004)
Addition	An inserted nontarget phoneme that is phonetically accurate
Omission	A deleted phoneme that may result from breakdown at the level of phonological retrieval or motor planning (Buchwald & Miozzo, 2012; Buckingham, 1986; Dell, 1988)