developments of historical long vowels (see previous section); for example, a may be pronounced with in words in which it was historically long. Consonants The Polish consonant system is more complicated; its characteristic features include the series of affricates and palatal consonants that resulted from four Proto-Slavic palatalizations and two further palatalizations that took place in Polish and Belarusian. Phonemes The consonant phonemes of Polish are as follows: The postalveolar sounds (sz, ż, cz, dż) and the corresponding alveolo-palatals (ś, ź, ć, dź) both sound similar to the English palato-alveolar consonants (the sh and ch sounds and their voiced equivalents). The tongue shape of the postalveolar sounds is similar to the shape postalveolar approximant (one of the realizations of the English /r/ phoneme, see also Pronunciation of English /r/). The alveolo-palatals are pronounced with the body of the tongue raised to the hard palate but a greater area of the front of the tongue is raised close to the hard palate compared to the English palato-alveolar sounds. The series are known as "rustling" (szeleszczące) and "humming" (szumiące) respectively; the equivalent alveolar series (s, z, c, dz) is called "hissing" (syczące). Polish contrasts affricates and stop–fricative clusters by the fricative components being consistently longer in clusters than in affricates. Stops in clusters may have either a plosive release accompanied by a weak aspiration or a fricated release (as in an affricate) depending on the rate of speech and individual speech habits. ('clean' fem.) vs. or ('three hundred'). ('jam') with vs. or ('take a nap' imper. sing.). Both realizations of stop-fricative clusters are considered correct and typically respelled as tsz, d-ż and czsz, dżż respectively in normative descriptions of Polish pronunciation. The distinction is lost in colloquial pronunciation in south-eastern Poland both being realized as simple affricates as in some Lesser Polish dialects. According to , , such a simplification is allowed in the standard language variety only before another consonant or before a juncture, e.g. trzmiel or ('bumblebee'), patrz or ('look', imper. sing.). For the possibility of an additional velar fricative for , see § Dialectal variation below. On the same grounds as for gives a phonemic status for speakers who have in their system. Allophones are labial except before where they are palatalized . have a labiodental allophone , which occurs before labiodental consonants (as in symfonia 'symphony' or konfiguracja 'configuration'). Before fricatives, orthographic nasal consonants m, n may be