Pronouncing of Hakaaram in Sanskrit

Hakaaram panchamairyuktam anta:sthaabhishca samyutam .

 Aurasyam tam vijaaniiyaat kaNthyamaahurasamyutam ..

 

Paaniniiyashikshaa 16

Panchama = all the fifth consonants of each vargah

Anta:sthah= 'yaN' pratyaaharah ie     ya, va ra, la, 

The rule clearly  states that if 'hakara' is followed by any of the above
alphabets, then it should  NOT be pronounced as 'KANTHYAM" but pronounced as
'AURASYAM'

"akuhavisarjaniiyanaam kanthah".... by this we know that 'hakarah' is
pronounced from the 'kantha'

But how do we pronounce 'aurasya' hakaarah. Is it lost? If any of the readers in this list, know or know any
scholar who knows how to pronounce 'Aurasya hakarah', do inform .

As this method of pronunciation is lost,we have to rely on the Vedic
scholars who learnt it orally from their acharyas.

As per the oral tradition, brahma is pronounced as bramha, pralhadah is
pronounced as prahlada, madhyahne is pronounced as madhyanhe and so on.

But if we apply the same logic, it is impossible to pronounce 'hyah' as
'yhah' which means 'yesterday'.

 

Nothing in the pANinIya shikShA or sUtras suggests that the order of 'h' and the other consonant cn be interchanged. Indeed pANinIya sUtras suggest quite clearly that 'h' is pronounced before.
The sUtras mentioned by shrI suma in reply to you are:
8.3.26 he mapare vA |
8.3.27 napare naH |
In both cases the anusvAra before the 'hm' or 'hn' is modified. If the 'h' was not pronounced before the m, n in these combinations, the anusvAra would be modified
 automatically by "8.4.58 anusvArasya yayi parasavarNaH" and these two sUtras become superfluous. Because we know that pANini does not make superfluous sUtras, we know that the 'h' is pronounced before the 'm' and 'n' respectively.

shrI. suma's teacher is quite right in insisting the correct pronunciation of the -mhm- and -nhn- combinations that are the subject of these sUtras. However, note that both of these sUtras are optional rules signalled by the "vA"
kiM + hmalayati = (Option 1) kiM hmalayati ; (Option 2) kimhmalayati

kiM + hnute = (Option 1) kiM hnute ; (Option 2) kimhnute
(So I hope shrI suma's teacher allows both the anusvAra-h-m and the -m-h-m- pronunciations.)

In any case for the original words 'hmalayati' or 'hnute' the order is that 'h' is pronounced before the nasal consonant.

Now what may be the reason as to why some regional accents of saMskRta switch the order of -hm- may have been reversed. By the time of the use of prAkRta languages such as pAlI, the combination -mh- -Nh- etc., have become common. e.g., the words tumhe, taNhA etc. (These combinations are never seen in saMskRta.) In the spoken standard version of the modern language Marathi, the combination -hm- is always converted to -mh-, etc., (e.g., brammha, Annhik, AvvhAn, etc., instead of the saMskRta words brahma, Ahnika, AhvAna, etc.). This is possibly a further development of this flow of phonetic change from the prAkRta languages. (I think, the same flow is true regarding
 kannaDa, but I am not sure.)

Our native (regional) languages strongly affect our saMskRta accents. Thus with a respectful bow towards our rich and honourable mother-tongues, I suggest that these regional language specialities are the reason why some speakers switch the order of -hm- to -mh-, as you note.