Production of certain English phonemes relies heavily on effort from the abdominal region, and under-utilization of this region by second language English speakers can create difficulties pronouncing these sounds. In particular, production of long vowel/diphthong sounds requires sustained abdominal contraction to maintain the length of these phonemes, and production of voiced fricative consonants requires a sharp burst of abdominal effort to expel air from the lungs to adequately voice the consonant. Both Cantonese and Mandarin speakers have particular problems producing these phonemes, and this study compared how instruction in the abdominal techniques effected production of these sounds by these two learner groups. The study focused on the vowel and diphthong sounds, /i?/, /u?/ and /[a diphthong]/, and the voiced fricative consonants, /z/,/[voiced dental fricative]/, /v/ and /[voiced postalveolar fricative]/. A previous study by the author had found the abdominal techniques improved Chinese learners' production of these phonemes. The learners in that study were evenly divided between Mandarin and Cantonese speakers, and this study reanalysed the data to examine which speaker group benefited more from these abdominal techniques. Results showed that the Mandarin speakers were the major beneficiaries of the techniques. Importantly, the study also explored, in depth, likely reasons for this.