IOE - Faculty of Education and Society


UCL Institute of Education launches world's first comprehensibility scale

18 May 2017

Students speaking, pronunciation

Dr Talia Isaacs from the IOE's Centre for Applied Linguistics has launched the world's first English comprehensibility scale, together with Canadian collaborators. The data-driven scale will help teachers more effectively target the most important linguistic factors for understanding second language English speakers.

Drawing on Dr Isaacs' extensive research in the field, the scale, which is intended for use in academic settings, explicitly states that it is not necessary to sound like a native speaker to achieve the highest level of comprehensibility. This differs from other scales, which often confound the strength of someone's accent with their level of comprehensibility.

As Dr Isaacs explains, "It is possible to have a detectable foreign accent and still be perfectly understandable, but someone who is genuinely difficult to understand is almost always judged to be heavily accented. Our scale takes accent out of the equation."

Dr Isaacs argues that few resources of this kind take stock of the research evidence: "Many current rating scales, such as IELTS, are so general when referring to 'comprehensibility' that it is difficult to pinpoint the factors that make someone easier or harder to understand at different scale levels."

"Universities in English speaking countries that welcome large numbers of international students, such as the UK and Canada, will find the scale useful for targeting spoken academic English as part of wider efforts to provide their students with greater support. Although many international students meet the English language entrance requirements for their programme, this does not guarantee that they are equipped with the language skills they need to succeed.

"The scale, which is intended for pedagogical purposes, including for use with pre-sessional students who hope to achieve a high enough score on the exit-exam to be admitted, could raise international students' awareness about their strengths and weaknesses and track their progress over time. It will also provide teachers with guidance on an instructional focus, based on the latest research evidence."

The scale is a product of an ongoing collaboration on what it takes to be understandable in a second language. It aims to reduce language barriers and promote skill-appropriate language learning behaviours. 

The scale, together with instructions for using it, is freely downloadable on IRIS.



  • UCL students in pronunciation class (courtesy of Jack Latimer via University College London).