deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
The sound called jihvAmUlIyaH जिह्वामूलीयः is a variant of H ः used optionally before k kh क्ख्.
It is a fricative sound made with the back of the tongue very near k क् position.
Listen to the audio of kupvoKkaFpauca for an example. (Actually most of these audios have Kk ⩆क् instead of Hk ःक्, listen to the aKkvipu अ⩆क्विपु at the end of bhrAjabhAsadh....)
I write this sound as Kk Kkh ⩆क्⩆ख् in this website, but only I write it as K. It is usually written as X or as H.
guruK kramati गुरु⩆ क्रमति
guruH kramati गुरुः क्रमति
guruX kramati
You should write it always as H ः. But yu should get into the habit of pronouncing everything that is written with Hk ःक् Hkh ःख् as Kk ⩆क् Kkh ⩆ख्, because that is easier than using a pure hiss.
Excepting, however, HkS ःक्ष्, where you MUST say a hiss —
pazyataH kSetram पश्यतः क्षेत्रम् "both see the field"
In this case saying the hiss is easier because your tongue is already somewhat curled up in anticipation for the S ष्.