Question

Assalaamu alaikum wa rahmatu Allahi wa barakaatuh.

Alhamdu li Allah for this site and May He reward you with good in this world and the next.

It is clear to me that we must round the mouth when saying a dhamma ( ). And also that we must return the mouth to the "neutral" position for a letter following a dhamma if it has a sukoon on this following letter. For example in the word:  " " we must round the mouth carefully and completely for the dhamma on the kaf and then return to neutral for the Ikhfa of the noon and then again rounding for the dhamma on the ta' and back to neutral for meem.

My question is: in the case of a word like, for example, " " i.e two letters with dhamma following each other, is it preferred to return the mouth to neutral before saying the Ha ()with a dhamma. Thank you for reading my question and jazakum Allahu khair.

 Answer

Wa alaikum assalaam wa rahmatu Allahi wa barakatuh.

May Allah reward you greatly for seeking knowledge and may Allah accept all your righteous deeds.

You are very correct in that our mouth should not be left in a dhammah when we have a saakin letter after a dhammah; if we do leave the mouth in a dhammah position, the sound of the saakin letter is affected and it will not be the correct desired sound. 

When there are two dhammahs in a row, or a lengthened  followed by a letter with a dhammah such as in the word  , we should not return our mouth to a neutral position in between letters since that would affect the preceding dhammah or lengthened .  The lengthened  can only be complete in sound with a complete dhammah, if the next letter has a dhammah, we would stay in the dhammah position so that each vowel can be pronounced fully.    We would only change the position of our mouth if the next letter did not have a dhammah, and this change would take place when starting the new letter.  
In summary, our mouth should be in the shape appropriate for the vowel accompanying the letter that we are pronouncing, if there is a sukoon (other than a medd letter), our mouth should be in a neutral position, if a dhammah we should have a circling of our lips; if a kasrah, we should lower our jaw; and if a fat-h, we should open our jaw in a vertical opening.  The only time our mouth should change position is when the vowel changes from one vowel (or a sukoon) to another.

A note: We changed the way you transliterated the word   from "domma" to "dhammah", to try and reflect the pronunciation of the word a little more.  The letter Dhaad (), as you are aware, is not one that is present in English, but many non-Arabs mistakenly pronounce it as a "d", which is not at all the correct articulation point.  Since the combination "dh" is not one normally found in English, it denotes a different letter than "d" and insha' Allah a student would take note of it and realize that they should not pronounce it as a "d".  The vowel on the letter dhad in the word   is a fat-h. 

Wa iyyakum wa-l-muslimeen.