Examining the linguistic aspects of speech that most efficiently discriminate between upper levels of the revised IELTS Pronunciation scale


Talia Isaacs

Pavel Trofimovich

Guoxing Yu

Bernardita Muñoz Chereau

Date Published:

1st March 2015

The goal of this study is to identify the linguistic factors that most efficiently distinguish between upper levels of the IELTS Pronunciation scale. Analyses of test-taker speaking performance, coupled with IELTS examiners’ ratings of discrete elements and qualitative comments, reveal ways of increasing the transparency of rating scale descriptors for IELTS examiners.

Following the expansion of the IELTS Pronunciation scale from four to nine band levels, the goal of this study is to identify the linguistic factors that most efficiently distinguish between upper levels of the revised IELTS pronunciation scale.

The study additionally aims to identify the trait-relevant variables that inform raters’ pronunciation scoring decisions, particularly as they pertain to the ‘comprehensible speech’ criterion described in the IELTS Handbook (IELTS, 2007) and to relate these back to existing rating scale descriptors.

Speech samples of 80 test-takers performing the IELTS long-turn speaking task were rated by eight accredited IELTS examiners for numerous discrete measures shown to relate to the comprehensibility construct, including segmental, prosodic, fluency, and lexicogrammatical measures. These variables, rated on separate semantic-differential scales, were included as predictors in two discriminant analyses, with Cambridge English pre-rated IELTS overall Speaking scores and scores on the Pronunciation subscale used as the grouping variables. Statistical outcomes were then triangulated with the IELTS examiners’ focus group data on their use of the IELTS Pronunciation scale levels and the criteria most relevant to their scoring decisions.

Results suggest the need for greater precision in the terminology used in the IELTS Pronunciation subscale to foster more consistent interpretation among raters. In particular, descriptors that were solely distinguished from adjacent bands by stating that the test-taker has achieved all pronunciation features of the lower band but not all those specified in the higher band had poor prediction value and were cumbersome for examiners to use, revealing the need for specific pronunciation features to be delineated at those levels of the scale.