The phonological system of the Polish language is similar in many ways to those of other Slavic languages, although there are some characteristic features found in only a few other languages of the family, such as contrasting postalveolar and alveolo-palatal fricatives and affricates. The vowel system is relatively simple, with just six oral monophthongs and arguably two nasals in traditional speech, while the consonant system is much more complex. Vowels The Polish vowel system consists of six oral sounds. Traditionally, it was also said to include two nasal monophthongs, with Polish considered the last Slavic language that had preserved nasal sounds that existed in Proto-Slavic. However, recent sources present for modern Polish a vowel system without nasal vowel phonemes, including only the aforementioned six oral vowels. Oral Close is close front unrounded . It is somewhat more open than cardinal . ranges from almost close-mid near-front to (advanced) close-mid central or alternatively from near-close near-front unrounded to close-mid central unrounded . These descriptions are essentially equivalent. Traditionally, is used in narrow transcriptions (as if close central unrounded). Older sources describe this vowel as follows: According to , it is intermediate between cardinal and , but closer to the latter one. Alternatively, it is intermediate between cardinal and , but closer to the former. He places it on a vowel chart closer to . According to it is articulated with the centre of the tongue raised up and moved somewhat forward; the pharynx also widens. She places it on a vowel chart closer to . According to , it is near-close central unrounded , with a close-mid central unrounded allophone being optional before and in some unstressed positions. A realization close to near-close near front unrounded is present in northeastern dialects. is close back rounded . It is somewhat more open than cardinal , and intermediate between them in terms of labialization. There is no complete agreement about the realization of between soft consonants: According to , it is close back somewhat fronted . According to , it is close central . According to , it is close centralized . Mid is open-mid front unrounded . It is somewhat more open than cardinal . There is no complete agreement about the realization of between soft consonants: According to , and , it is close-mid front unrounded . According to , it is either mid front unrounded or mid retracted front unrounded