Shalom achi,
No. I do not know what you mean by lost sound. What I believe is that certain Hebrew letters had more than one sound, which for one reason or another that is no longer the case. Aleph today, from what I understand, is considered a glottal stop, with no sound of its own. I do not believe it was that way originally. I do not consider the sound lost, but simply no longer used, or used differently than was done originally.

Along with this, I have no evidence from scripture about any of the letters' sounds. I only know, for example, that a ד makes a 'd' sound because of what we are told. It would have been great if the Creator gave us somewhere in scripture an exact phonetic pronunciation of every letter, and what each means, but he chose not to do that.

Ronen

Shalom Ronen,

The creator chose not to provide pronunciations because pronunciation is not the matter of importance from the creator's point of view.

What makes you think that God would want everyone to pronounce every word similar to other people??

I could easily imagine walking through twelve tribes of Israel and find several different pronunciations of single word. Come here, I take you through some 30 provinces and see how one single common Semitic word is pronounced with various nuances of its own throughout the region. Even in one province, you find various nuances for one Semitic word.

Shalom Ronen and Ali!
You both bring up an interesting discussion regarding letter pronunciation.
The way I look at it is that Gen 11 shows that at that time the whole earth was ''...was of one language, and of one speech." Instead of spending a whole lot of research time on this verse, which i know we have all done at some time, I feel it is better to look at Acts 2.
The reasoning is that Acts 2 is the reversal of Gen 11. The important point is that in Act 2:1 '...when the day of Pentecost was fully come, they were all with one accord in one place'.
This, I believe, is the goal...that is, for all men to be in one accord.
This section of scripture has the miraculous phenomenon of speaking in multiple languages in order to achieve this purpose. People of all parts and languages, came to be unified, not by pronunciation, but by the message that that pronunciation gave.
Shalom,
Matt

_________________
Paleo-Hebrew Converter Tool, go here:
https://alittlehebrew.com/paleo/
Hebrew Character Picker, go here:
https://r12a.github.io/pickers/hebrew/
Am ha-Aretz Translit(Heb to Eng Keyboard), go here:
https://bumba.net/~skaya/hebrew/translit/ahtModified.html
To post in Modern Hebrew, go here: https://www.lexilogos.com/keyboard/hebrew.htm
or here, https://www.branah.com/hebrew
For More Root Searches, go here: http://qbible.com/hebrew-old-testament/ or here: https://www.2letterlookup.com/
Gesenius Heb/Chald Lexicon Online: https://www.tyndalearchive.com/tabs/Gesenius/
Brown/Driver/Briggs 1906 Enhanced Lexicon:http://www.ericlevy.com/revel/bdb/bdb/main.htm
Benner: Ancient Hebrew Lexicon of the Biblehttps://www.ancient-hebrew.org/ahlb/aleph.html
Dictionary of Targumim,Talmud Babli,Yerushalmi, Midrashic Literature Online:
https://www.tyndalearchive.com/tabs/jastrow/
Edenics English to Hebrew Word Tracer Tool: https://www.edenics.net/english-to-hebrew.aspx
Comprehensive Aramaic Lexicon: http://cal.huc.edu/
BAG(now BDAG) Greek-English Lexicon:http://lareopage.free.fr/a&g/main.htm
Arabic/English Lexicon:https://www.tyndalearchive.com/tabs/lane/

Shalom Ronen and Ali,
After much contemplation, I have come to the same conclusion. Hebrew always had 22 letters (in all its stages), but that the two sounds Ghayin and Ayin both stem from one letter originally (ע) much like ש which represents 2 sounds: the Shin and a lateral 's' sound, Sin (like שלום shalom and ישראל Yisrael).

I should also mention that ח had two sounds as well as is seen in LXX transliterations: Hheth and Kheth (compare Arabic ح Hhaa and خ Khaa).

Peace and blessings.
Shalom

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"You shall know the Truth, and the Truth shall make you free." -- John 8:32