Biblical Hebrew had a typical Semitic consonant inventory, with pharyngeal /ʕ ħ/, a series of “emphatic” consonants (possibly ejective, but this is debated), lateral fricative /ɬ/, and in its older stages also uvular /χ ʁ/. /χ ʁ/ merged into /ħ ʕ/ in later Biblical Hebrew, and /b ɡ d k p t/ underwent allophonic spirantization to [v ɣ ð x f θ] (known as begadkefat spirantization). The earliest Biblical Hebrew vowel system contained the Proto-Semitic vowels /a aː i iː u uː/ as well as /oː/, but this system changed dramatically over time.
By the early Middle Ages, /ɬ/ had shifted to /s/ in the Jewish traditions, though for the Samaritans it merged with /ʃ/ instead. The Tiberian reading tradition of the Middle Ages had the vowel system /a ɛ e i ɔ o u ă ɔ̆ ɛ̆/, though other Medieval reading traditions had fewer vowels.
A number of reading traditions have been preserved in liturgical use. In Oriental (Sephardi and Mizrahi) Jewish reading traditions, the emphatic consonants are realized as pharyngealized, while the Ashkenazi (eastern European) traditions have lost emphatics and pharyngeals, and show the shift of /w/ to /v/. The Samaritan tradition has a complex vowel system which does not correspond closely to the Tiberian systems.
Modern Hebrew pronunciation developed from a mixture of the different Jewish reading traditions, generally tending towards simplification. Emphatic consonants have shifted to their ordinary counterparts, /w/ to /v/, and [ɣ ð θ] are not present. Many Israelis merge /ʕ ħ/ with /ʔ χ/, do not have contrastive gemination, and pronounce /r/ as a uvular trill [ʀ] rather than an alveolar trill, as in many varieties of Ashkenazi Hebrew. The consonants /tʃ dʒ/ have become phonemic due to loan words, and /w/ has similarly been re-introduced.