Ever since the spoken usage of Mishnaic Hebrew language ended in the second century AD, Hebrew had not been spoken as a mother tongue. Be that as it may, during the Middle Ages, the language was used by Jews in a wide variety of disciplines. This usage kept alive a substantial portion of the traits characteristic of Hebrew.
First and foremost, Classical Hebrew was preserved in full through well-recognized sources, chiefly the Tanakh (especially those portions used liturgically like the Torah, Haftarot, Megilot, and the Book of Psalms) and the Mishnah. Apart from these, Hebrew was known through hymns, prayers, midrashim, and the like.
During the Middle Ages, Hebrew was used as a written language in Rabbinical literature, including in judgments of Halakhah, Responsa, and books of meditation. In most cases, certainly in the base of Hebrew's revival, 18th and 19th century Europe, the use of Hebrew was not at all natural, but heavy in flowery language and quotations, non-grammatical forms, and mixing-in of other languages, especially Aramaic.
The use of Hebrew was not only in written language. Hebrew was also used as an articulated language, in synagogues and in batei midrash. Thus, Hebrew phonology and the pronunciation of vowels and consonants were preserved. Despite this, in the region the influence of foreign tongues caused many changes, leading to the development of three different forms of pronunciation:
Ashkenazi Hebrew, used by Eastern and Western European Jews, which maintained mostly the structure of vowels but may have lost the stress, and the gemination, although this cannot be known for sure, as there are no recordings of how the language (or its respective dialects) sounded e.g. in Kana'an; it should be noted that Ashkenazi Hebrew pronunciation has a variation of vowels and consonants, which follows closely the variation of the vowel and consonant signs written down by the masoretes around the 7th century CE, indicating that there is a strong link with the language heard by them. E.g. where we see two different vowel signs, or a consonant with resp. without a dogeish (dagesh), a difference is also heard in the various Ashkenazic pronunciations.
Sephardic Hebrew, used by Mizrahi Jews, preserved a structure different than the recognized Tiberian Hebrew niqqud of only five vowels, but did preserve the consonants, the grammatical stress, the dagesh, and the schwa; yet, different ways of writing consonants are not always heard in all Sephardic pronunciations. E.g. the Dutch Sephadic pronunciation does not make a difference between the beth with and without dagesh: both are pronounced as "b". The "taf" is always pronounced as "t", with or without dagesh. There are two possibilities: the difference disappeared over time in the Sephardic pronunciations, or it never was there in the first place: the pronunciation stems from a separate Hebrew dialect, which always was there, and which e.g. the masoretes did not use as reference.
Yemenite Hebrew language, which, though by some believed to preserve almost all the Classical Hebrew pronunciation, was barely known where the revival took place.
Within each of these groups, there also existed different subsets of pronunciation. For example, differences existed between the Hebrew used by Polish Jewry and that of Lithuanian Jewry and of Germany Jewry.
According to evidence discovered by researchers, it appears that in the fifty years preceding the start of the revival process, a version of spoken Hebrew already existed in the markets of Jerusalem. The Sephardic Jews who spoke Ladino or Arabic and the Ashkenazi Jews who spoke Yiddish needed a common language for commercial purposes. The most obvious choice was Hebrew. Though Hebrew was spoken in this case, it must be noted that it was not a native mother tongue, but a common language of limited use, a sort of Jewish lingua franca.
The linguistic situation the background of which the revival process occurred was then a situation of diglossia, when two languages--one of prestige and class and another of the masses--exist within one culture. In all of Europe, this phenomenon has waned, starting with English in the 16th century, but there were still differences between spoken street language and written language. For example, Russians spoke popular Russian to each other, but wrote in more prestigious Russian or French, while Germans spoke in local dialects and wrote in Standard German. The Jews had a similar situation: Yiddish was the spoken language, and the written language was Hebrew for liturgical purposes and the language of the broader culture - be it Russian, German, French, or Czech - for secular purposes
1. European Zionists restored Hebrew but they were not able to successfully restore the proper SYNTAX because of the expanding regions of those who considered themselves Hebrew. Thus we have a plethora of so-called "Hebraic" languages with a small margin for standard in syntax.
2. In fact, many, many common words in today's Hebrew was simply BORROWED from Arabic.
3. The revival of Hebrew came marginally with errors and variations in SYNTAX.
So for example, depending upon what scholar you read.. Elah, and Alah are both used for Strong's Concordance #H426.
Parts of this essay were excerpted from Wikipedia