There is significant phonological variation among the various Yiddish dialects. The description that follows is of a modern Standard Yiddish that was devised during the early 20th century and is frequently encountered in pedagogical contexts.
Contents
Consonants
As in the Slavic languages with which Yiddish was long in contact (Russian, Belarusian, Polish, and Ukrainian), but unlike German, voiceless stops have little to no aspiration; unlike many such languages, voiced stops are not devoiced in final position. Moreover, Yiddish has regressive voicing assimilation, so that, for example, זאָגט /zɔɡt/ ('says') is pronounced [zɔkt] and הקדמה /hakˈdɔmɜ/ ('foreword') is pronounced [haɡˈdɔmɜ].
Vowels
The vowel phonemes of Standard Yiddish are:
In addition, the sonorants /l/ and /n/ can function as syllable nuclei:
[m] and [ŋ] appear as syllable nuclei as well, but only as allophones of /n/, after bilabial consonants and dorsal consonants, respectively.
The syllabic sonorants are always unstressed.
Comparison with German
In vocabulary of Germanic origin, the differences between Standard German and Standard Yiddish pronunciation are mainly in the vowels and diphthongs. Examples are the German long /aː/ as in Vater ('father'), which corresponds to /ɔ/ in Yiddish פֿאָטער /ˈfɔtɛr/, and the German long /eː/ and long /oː/, which correspond to diphthongs in Yiddish (/ɛɪ/ and /ɔɪ/). As in many Germanic languages, Yiddish lacks the German front rounded vowels /œ, øː/ and /ʏ, yː/. They are replaced in Yiddish by /ɛ/ (in case of the short /œ/), /ɛɪ/ (in case of the long /øː/) and /ɪ/ (in case of /ʏ, yː/), respectively.
Diphthongs have also undergone divergent developments in German and Yiddish. Where Standard German has merged the Middle High German diphthong ei and long vowel ī to ei (pronounced /aɪ/), Standard Yiddish has maintained the distinction between them as /ɛɪ/ and /aɪ/, respectively. The German /aʊ/ (as in kaufen, 'buy') corresponds to the Yiddish /ɔɪ/ (in קױפֿן /kɔɪfn/); lastly, the German /ɔʏ/, as in Deutsch 'German') corresponds to /aɪ/ in Yiddish (in דײַטש /daɪtʃ/). Another difference is that the vowel length distinctions of German do not exist in Standard Yiddish.
There are consonantal differences between German and Yiddish. Yiddish deaffricates the Middle High German voiceless labiodental affricate /pf/ to /f/ initially (as in פֿונט funt; though this pronunciation is also quasi-standard throughout northern and central Germany); /pf/ surfaces as an unshifted /p/ medially or finally (as in עפּל /ɛpl/ and קאָפּ /kɔp/). Additionally, final voiced stops appear in Standard Yiddish but not Northern Standard German.