Of the two examples you've provided, one 'Yeh-hoo-ahh' is from Greg Stafford, and one 'I_Eh_ou_Ah' is from Gérard Gertoux? Is that right? In all honesty neither sound anything like Jehovah - which in itself is still a hybrid word.
If there was a correct pronunciation of the Divine Name we'd know it by now. The WT has it wrong. And that is important as they claim to be God's sole channel of communication.
By the way there is an review on Amazon of the book that maybe of interest to you:
Linguists recognise that in the evolution of a language, the vowels change more noticably than the consonents. For example, The short vowels of British Recieved Pronunciation are manifested as dipthongs or even tripthongs in many accents of the Southern United States. In 1940s Britain, the present [æ] phoneme was pronounced more like [e], and this is a time difference of only 60 years!!!
Anglo-Saxon words of 900 years ago, are recognised by etymologists as antecendents of Modern English primarily by their consonents, because vowels, semi-vowels, and glides change even from generation to generation. The Anglo-Saxon language of 900 years ago is a "foreign language" in that it has changed beyond recognition due to linguistic factors such as ablaut, semi-vocalisation, palatisation.
The fact that the name YHWH is made up entirely of slippery semi-vowels, and possibly aspirants, renders it very difficult for linguists to extrapolate an original form.
palatal [j] --- semi-vowel [y] --- vowel[i]
labiodental[v] --- biablial[β] --- semi-vowel[w] --- vowel[u]
(This demonstrates semi-vocalisation, palatisation and the forming of approximants)
Ablaut is shown in the gradual vowel changes of the Proto-Indo-European *[pod] to the Latin *[ped] to the authors own language French: 'pied' [pye] ('d' not reflected in modern pronunciation)
To be objective though, the change from PIE *[pod] to the Anglo-Saxon [fo:t] to our present pronunciation of 'foot' [fut] is less striking with regard to consonent preservation, but we still notice a general trend of vowel "slipperyness".
Ablaut (or apophony) is also demonstrated by the the pluralisation of 'man' to 'men' or that of 'goose' to 'geese'. This is common in Amharic, ANOTHER SEMITIC LANGUAGE.
ASSUMING that the Hebrew language underwent linguistic changes similar to Amharic, in the 1070 years between the first and last books of the Old Testanment (compared to the 900 years between Beowulf and the present literature), it is quite possible that many pronunciations of The Name came in and went out of use, especially in view of the Jewish prohibition of pronouncing the name.
Due to the ablaut of the unwritten and "un-pin-downable" vowels in Hebrew, the name Y.eH.oW.aH (Jehovah/Yehowah), could easily have been Y.aH.oW.eH (Yahweh/Yahoweh) or even hypothetical Y.iH.uW.H (Jihuβh) or iY.H.uW.H (Ihuh).
I appreciate the depth of research and reasoning that Gertoux has undertaken but i still believe from a linguistic point of view that is impossible to determine the original pronunciation of The Name and therefore any dogmatic attempts to support ANY of the varients are futile, even with the support of personal names such as Yehoshuah/Yahushuah/Yeshua.