In this article, Gibson traces the relationship between stress placement and vowel quality/quantity through the history of Hebrew. He begins by dividing Hebrew into three main stages: proto-Hebrew (PH), Biblical Hebrew (BH), and Masoretic Hebrew dealing primarily with Tiberian Hebrew (TH). Jakobson and Halle have argued that vowel quantity and stress tend not to both have phonemic status at the same time in a language. Gibson’s thesis is that it was vowel quantity that was phonemic in PH, but that the situation was reversed by BH with stress becoming phonemic instead. This results in quality replacing quantity as the more distinctive feature of vowels.
Gibson draws evidence for Biblical Hebrew from the first millennium until the first few centuries of the Christian era. This includes the consonantal text of the Hebrew Bible, the Dead Sea Scrolls, and the various Hebrew transcriptions in Greek and Latin. Masoretic Hebrew is represented by the vocalized manuscripts from the medieval period. These texts preserve the consonantal structure of the biblical text, but reflect a pronunciation maintained in the academy centuries after Hebrew has ceased to be spoken. Proto-Hebrew must be reconstructed on the basis of common Northwest Semitic from the second millennium as represented by Ugaritic, Amorite, and Amarna Canaanite. Gibson assumes that NWS was a relative unity during this period and that the division of Canaanite and Aramaic cannot be traced back beyond 1000 BCE.
The consonantal phonemes of BH and TH were identical, though gemination must have had phonemic status in BH as shown by the minimal pair kabed (Qal pf 3ms) : kabbed (Piel pf 3ms). PH can be reconstructed with six vowel qualities: /a/, /i/, /u/, /e/, /o/, and a second long a-vowel /a2/. This a2 seems to be somewhere in between an open back and open front a. The /e/ and /o/ vowels merge with the reduced diphthongs from /ay/ and /aw/ respectively, and /o/ also merges with the result of the Canaanite shift /ā/ > /ō/. BH seems to have the same inventory of vowels. However, in TH there are nine vowel qualities. The seven full vowels are /a/, /ε/, /i/, /ɔ/, /o/, and /u/. Thus TH has added /ε/, and /a2/ has opened to /ɔ/. TH also adds the shewa /ə/ and the hateph-qamets. the other reduced vowels seem to be allophonic.
A general stress shift seems to have occurred in the transition period c1300-1000 BCE. This seems to have been a time of great phonological and grammatical change in NWS, most notably the loss of final short vowels. In PH stress seems to have followed Arabic pattern with vowel length being an important factor in determining stress placement. A long vowel attracted the stress when in the penultimate or some previous syllable. If there are only short vowels, then stress moves to the beginning of the word. For example, the change of PH *ˤa2lamu > TH ˤolam indicates that stress must have been on the first syllable during the Canaanite shift. In contrast *ˀata2 ‘you’ > ˀatɔ, suggesting that unstressed /a2/ did not participate in the Canaanite shift.
With the drop of final short vowels and the resulting changes, the main stress was freed from vowel quantity. It now fell on the ultimate or penultimate syllable without regard for the vowel length or the type of syllable. The separation of stress from vowel quantity began the process of switching stress to a phonemic status instead of vowel quality. This also began a process of changes in vowel qualities as the prosody changed.
There seem to be two systems of vowel changes. In both /i/ > /e/ and /u/ > /o/. The difference is whether /a/ > /a2/ or not. In nouns like *dabaru, the loss of the final vowel closes the final syllable and the stress shifts to the ultimate so that /a/ > /a2/, *dábaru > dabá2r. However, in nouns like ˀiṣbaˤu where the first syllable is closed or contains a long vowel, generally /a/ does not shift even though the stress shifts to the ultimate, *ˀíṣbaˤu > ˀiṣbáˤ ‘finger’.
In closed syllables, stressed short vowels seem to have been retained in BH, at least in the dialect underlying the Secunda: PH gabru > BH gabr (Sec γαβρ). However, Qumran orthography suggests a change in quality of /u/ and perhaps /i/ had already begun, as in שוחוד ‘bribe’ (1QIsaa 38:20) which suggests *šuḥdu > šuḥd > šəḥod or šoḥəd.
Forms that ended with a geminate consonant lost the gemination when the final vowel elided. Here also /a/ does not shift to /a2/, thus PH *libbu > BH leb, but PH *rabbu > BH rab. Based on Ugaritic, final /w/ or /y/ had already assimilated to the following short vowel at the PH stage. Again, /a/ does not shift, thus PH pírī > BH péri > TH pərí, while PH gádī > BH gádi > TH gədí.
Short vowels in open syllables preceding the newly shifted stress underwent no change from PH to BH. However, in TH /a/ and /i/ followed the normal path of development, /a/ > /a2/ > /ɔ/ and /i/ > /e/. Short vowels in propretonic positions reduced to zero in BH and thus /ə/ in TH. A /u/ in these positions is extremely rare, but seems to have gone unchanged.
The verbal system is also quite complicated. Gibson reconstructs six verbal forms in PH: yiqáttal, yáqtulu, yáqtula, yáqtul, qtúl, and qátala. The first form, yiqáttal, seems to have merged with yáqtulu during the PH stage (note that scholars now generally reject a yiqáttal form for common NWS, see Terry Fenton, “The Absence of a Verbal Formation *yaqattal from Ugaritic and North-west Semitic,” JSS 15 (1970): 31-41).
When the short vowels dropped, yáqtulu and yáqtula merged with yáqtul. The resulting verb had the semantic range of present-future (imperfect) indicative, past indicative, subjunctive, and jussive. The qátala form also has a bivalence between past indicative and future indicative in certain contexts. This seems like unbelievable multivalence for single verb forms, but fortunately, in BH and TH, stress often helps differentiate between the past and future meanings. Gibson suggests that this is some of the strongest evidence that stress has indeed become phonemic in BH and TH.
In the regular verb, the inflected forms had stress on the penultimate syllable when it was closed, and it remained there in BH and TH. One would expect the following short vowels to drop when in an open syllable, but in the majority of cases they did not. For instance PH *qátalta (2ms) > TH qɔ´taltɔ (orthographically קטלת). But in BH we have forms in the Secunda such as αφαχθ suggesting qátalt while from Qumran we have אמרתה suggesting qátalta2. Gibson suggests that this reflects dialectal differences from PH, thus there was a PH qátalta and a qátalta2 form. Similarly he suggests a qátalti and a qátaltī (2fs), etc. The forms with short vowels dropped, while the other vowels shifted /a/ > /a2/ and /ī/ > /i/, etc.
In the other forms, stress shifted to the penultimate syllable accompanied by the loss of final short vowels. Thus PH *qátala > BH qatál and PH *qátalat > BH qatála2. In TH, stress shifts to the ultimate for forms with final vowels, and the previously stressed vowels reduce to shewa, thus BH qatála2 > TH qɔtəlɔ´.
Returning to the bi-valence of PH yaqtul(u) and qatala, the past value of yiqtol and future value of qɔtal is only maintained in the so-called waw consecutive constructions. Note that the wa-yiqtól form already disrupts the stress pattern by maintaining the full vowel on the copula, which the Masoretes also note by adding a dagesh to the following consonant. This should be considered a case of internal juncture. With the weqɔtál form, however, the waw is joined as usual.
In the weqɔtál form, stress is distinguished in only two cases, the 2ms weqɔtaltɔ´, and the 1cs weqɔtaltí. The movement of stress has not left any perceptible changes in the vowel quality, and thus it seems that this movement of stress to the final syllable is a late innovation of the Masoretic period. In the wa-yiqtól form stress distinguishes I-y verbs as well as those of the form sɔbab (> sab) and qɔm. Thus PH yéšib(u) > BH/TH yéšeb, but PH wa-yéšib(u) > BH wa-yéšib > TH wa-yéšεb. Also PH yáqum > BH yáqom > TH yɔ´qom, but PH wáyaqum > BH wa-yá2qum > TH wa-yɔ´qɔm.