An acoustic study of the RP English LOT and THOUGHT vowels

While there is variation among existing impressionistic accounts where the description of the RP English LOT and THOUGHT vowels is concerned (compare Wells 1982 (vol. I), Collins & Mees 2003, Roach 2004, Cruttenden 2008), not much attention has been paid to this issue in acoustic studies of RP (e.g. Wells 1962, Deterding 1990, Hawkins & Midgley 2005). In the present study, seven female native speakers of RP or near-RP born between 1985 and 1993 (i.e. speakers aged between 18 and 25 years at the time of the study) were recorded saying English words containing monophthongal vowels. In addition, data consisting of read speech from 18 male native speakers of RP or near-RP born between 1983 and 1991 (i.e. speakers aged between 18 and 25 years at the time they were recorded) contained in the DyViS database (Nolan et al. 2009) were analysed. The data were analysed acoustically by measuring F1 and F2 and normalising the measurements according to Lobanov's (1971) formula along with the mean F1 and F2 frequencies reported in Wells (1962), Deterding (1990) and Hawkins & Midgley (2005). Statistical analysis revealed statistically significant differences between the F1 formant measurements of the seven female speakers and the 18 male speakers versus Hawkins & Midgley's speakers born between 1946 and 1951; mean F1 was higher for the speakers born between 1946 and 1951. As for the THOUGHT vowel, the F1 measurements overlapped with the means relating to all different age groups in Hawkins & Midgley's (2005) data. It is suggested that RP LOT is undergoing raising whereas there is no strong evidence of any shift of the THOUGHT vowel.