I've always understand conventional Jewish belief is that there are different aspects to the soul, and each one provides different abilities. The נפש is common to all living creatures and it is the source of life. The נשמה is unique to humans, and it's what provides שכל/intelligence as well as the ability to speak (some refer to this as the רוח specifically). What that means then is before Man received the נשמה, there was no ability to speak. Sources which show this are as follows:
The beginning of Bereishis describes the creation of Adam
בראשית ב:ז
וייצר יקוק אלקים את האדם מן האדמה ויפח באפיו נשמת חיים, ויהי האדם לנפש חיה
And G-d formed man from the earth, and blew into his nostrils a נשמה of life, and man became a living being
Targum Onkelos translates the last half of the verse as
ונפח באנפוהי נשמתא דחיי והות באדם לרוח ממללא
And He blew into his nostrils a נשמה of life, and there was in man a talking spirit
Meaning, Man after receiving the נשמה became able to speak.
The Ramban on this verse comments similarly:
י...'וייצר יקוק אלקים את האדם' יצירת תנועה...ואחרי שיצרו בהרגשה, 'נפח באפיו נשמת חיים' מפי עליון, להוסיף הנפש הזאת על היצירה הנזכרת, ויהי האדם כולו לנפש חיה, כי בנשמה הזאת ישכיל וידבר
'And G-d formed man', the formation of the ability to move. And after he formed him with this ability, 'He blew into his nostrils a נשמה of life' from the mouth of the Upper One. This נפש was to increase on the formation previously mentioned. And man became entirely a living being, because with this נשמה he became intelligent and could speak
However, I believe contrary to this is what Rav Dessler writes in מכתב מאליהו חלק א pp. 72
י...כבר היה אדם טרם שנופחה בו נשמתו...ונפשו גדולה מנפשות שאר הברואים, משכלת היא בחכמה, פירוש שיש לו גם שכל וגם כח הדיבור וההסבר מה שאין כן בשאר בעלי חיים. ואחר כך שם בו הקדוש ברוך הוא אל הנשמה הקדושה, היינו כח קדושה עליונה.
...Man existed before the נשמה was blown into him...[Man's] נפש is greater than the נפשות of other creatures, for it is intelligent with wisdom. Meaning, it has both intellect and the ability to speak and to explain. This is not true for other creatures. Afterwards, The Holy One, Blessed is He, placed in [Man] the Holy נשמה, meaning the upper holiness.
Is there a source for what Rav Dessler is saying? It's not what he's focusing on and says it as if it's something that doesn't need explanation. But it is contrary to the sources I'm familiar with.
