Allophones Allophones are speech sounds which are non-contrastive in a language. Their occurrences are predictable from their environment, whereas the distribution of phonemes is not predictable. Affricates Affricates are known as contour segments. The IPA transcription of affricates reflects this dual nature. The air pressure required to create the former is much greater than the air pressure required for the latter.
Vowels are also approximants.
A fundamental division among the Indo-European languages is between the centum and satem groups which are named after the Latin and Avestan words for 'hundred' respectively. Although this division seemed to distinguish the western IE languages from the eastern ones, the discovery of Tocharian, a centum language near the western Chinese border, showed that the satem languages belonged to a central, innovating area, while the centum languages belonged to a periphery where this change did not occur. The insertion of a segment to correct aberrations in syllable structure and articulation. There are no direct records for it with the language being reconstructed from extant IE languages. The language was spoken about 5000 years ago somewhere in a range from western Russia into eastern Europe.