Tuinman, A., Mitterer, H., & Cutler, A.
(2011). Perception of intrusive /r/ in English by native, cross-language and cross-dialect listeners. Journal of the Acoustical Society of America, 130, 1643-1652. doi:10.1121/1.3619793.
In sequences such as law and order, speakers of British English often insert /r/ between law and and.
Acoustic analyses revealed such “intrusive” /r/ to be significantly shorter than canonical /r/. In a
2AFC experiment, native listeners heard British English sentences in which /r/ duration was manipulated
across a word boundary [e.g., saw (r)ice], and orthographic and semantic factors were varied.
These listeners responded categorically on the basis of acoustic evidence for /r/ alone, reporting ice after short /r/s, rice after long /r/s; orthographic and semantic factors had no effect. Dutch listeners proficient in English who heard the same materials relied less on durational cues than the native listeners,
and were affected by both orthography and semantic bias. American English listeners produced
intermediate responses to the same materials, being sensitive to duration (less so than native,
more so than Dutch listeners), and to orthography (less so than the Dutch), but insensitive to the
semantic manipulation. Listeners from language communities without common use of intrusive /r/
may thus interpret intrusive /r/ as canonical /r/, with a language difference increasing this propensity more than a dialect difference. Native listeners, however, efficiently distinguish intrusive from canonical
/r/ by exploiting the relevant acoustic variation.