Phonemic contrast refers to a minimal phonetic difference, that is, small differences in speech sounds, that makes a difference in how the sound is perceived by listeners, and can therefore lead to different mental lexical entries for words. For example, whether a sound is voiced or unvoiced (consider /b/ and /p/ in English) matters for how a sound is perceived in many languages, such that changing this phonetic feature can yield a different word (consider bat and pat in English); see Phoneme. Another example in English of a phonemic contrast would be the difference between leak and league; the minimal difference of voicing between [k] and [g] does lead to the two utterances being perceived as different words. On the other hand, an example that is not a phonemic contrast in English is the difference between [sit] and [siːt]. In this case the minimal difference of vowel length is not a contrast in English and so those two forms would be perceived as different pronunciations of the same word seat.
Phonemes and allophones Different phonetic realizations of the same phoneme are called allophones. Specific allophonic variations, and the particular correspondences between allophones (realizations of speech sound) and phonemes (underlying perceptions of speech sound) can vary even within languages. For example, speakers of Quebec French often express voiceless alveolar stops (/t/) as an affricate. An affricate is a stop followed by a fricative and in this case sounds like the English 'ch' sound. While this is an allophone of a single phoneme to speakers of Quebec French, to speakers of Belgian French this is heard as a stop followed by a fricative, or in other words as two different phonemes. This was accomplished by asking Belgian French speakers to repeat an utterance containing this affricate backwards, which resulted in the production of two separate sounds. If these speakers understood the affricate as a single sound, an allophone meant to stand in for the standard pronunciation [t], and not as two consecutive sounds, they would have reproduced the affricate exactly as is when they repeated the utterance backwards. It is important not to confuse allophones, which are different manifestations of the same phoneme in speech, with allomorphs, which are morphemes that may sound different in different contexts. An example of allomorphy would be the English plural marker /s/, which can manifest as [s], [z], and [əz] (cats [kæts], dogs [dɒgz], and horses [hoɹsəz]).
Phonological gaps An accidental gap is a phenomenon in which a form that could plausibly be found in a given language according to its rules is not present. In phonology, this is called a phonological gap, and it refers to instances in which a set of related segments containing various contrasts, e.g. between voicing (whether or not the vocal cords vibrate) or aspiration (whether a puff of air is released), is lacking a particular member. A contrast that the language could have had is then not realized within the actual language. For example, Thai has several sets of stop consonants that differ in terms of voicing and aspiration, yet the language has no voiced velar consonant [ɡ], as shown in the table of Thai stop contrasts below.
Acquisition of contrasts
In infants When infants acquire a first language, at first they are sensitive to all phonetic contrasts, including those that constitute phonemic contrasts not found in the language they are presently acquiring. Sensitivity to phonemic contrasts is important for word learning, and so infants will have to figure out which contrasts are important for their language and which are not. Some contrasts will confer a change in meaning between words, and others will not. Over the first year of life, infants become less sensitive to those contrasts not found in their native language. Studies have shown, however, that infants do not necessarily pay attention to phonemic differences when acquiring new lexical entries, e.g., 14-month-olds given the made-up labels "daw" and "taw" for new objects used these labels interchangeably to refer to the same object, even though they were capable of perceiving the phonetic difference between /d/ and /t/ and recognizing these as separate phonemes. In bilingual infants (those acquiring two languages simultaneously), contrasts must be both acquired and kept separate for the two languages, as contrasts present in one language may be allophonic in the other, or some of the phonemes of one language may be absent entirely in the other. The necessity of this separation has implications for the study of language acquisition and in particular simultaneous bilingualism, as it relates to the question of whether infants acquiring multiple languages have separate systems for doing so or whether there is a single system in place to handle multiple languages. (See Crosslinguistic influence.)
… excerpt ends here. Continue reading the full article.
