hierarchy, namely, that a rhotic is any sound that patterns as being more sonorous than a lateral consonant but less sonorous than a vowel. The potential for variation within the class of rhotics makes them a popular area for research in sociolinguistics. Variable rhoticity English English has rhotic and non-rhotic accents. Rhotic speakers pronounce a historical in all instances, while non-rhotic speakers only pronounce at the beginning of a syllable. Dutch Colloquial Northern Dutch speech of the Randstad region is variably rhotic. In the syllable coda, the sequences may be realized as , which may close to or the same as the vowels or sequences , resulting in a variable merger. For instance, kerk 'church' and cake 'pound cake' may become homophonous as (the diphthongal allophone of is usually transcribed ), whereas maar 'but' can be homophonous with maai '(I) mow' as . and are usually somewhat distinct from and as the former feature vowels that are more central (and features a diphthong in certain dialects, such as Rotterdam Dutch). After , may be dropped altogether, as in kilometer 'kilometer'. This is commonly heard in The Hague. It is not necessarily restricted to the word-final position, as it can also happen in word-final clusters in words such as honderd 'hundred'. After , , , and , may be realized as a centering glide, as in mier 'ant', muur 'wall', moer 'queen bee', meer 'lake' and deur 'door'. As with and , these vowels are more central (and also longer) than in other contexts. Furthermore, both and are raised in this context, so that meer becomes a near-homophone of mier, whereas deur becomes a quasi-rhyme of muur. In citation forms, in the syllable coda is pronounced as a pharyngealized pre-velar bunched approximant (known in Dutch as the Gooise r) that is acoustically similar to : etc. Other realizations (alveolar taps and voiced uvular fricatives) are also possible, depending on the region and individual speaker, so that mier may be also pronounced or . The pre-velar bunched approximant as well as the palatal approximant realization of described above are virtually unknown in southern varieties of Dutch. In the varieties where they do occur, they are restricted to the syllable coda. In other environments, is realized as or . Other Germanic languages The rhotic consonant is vocalized in the syllable coda in other Germanic languages, notably German, Danish, western Norwegian and southern Swedish.