Original
अतोऽतीन्द्रिययैवैते शक्त्या शक्तिमतीन्द्रियाम् ।
इन्द्रियस्यादधाना हि स्फुरन्ति व्यक्तिहेतवः ॥ २१७३ ॥ato’tīndriyayaivaite śaktyā śaktimatīndriyām |
indriyasyādadhānā hi sphuranti vyaktihetavaḥ || 2173 ||“Thus the conclusion is that it is by means of the imperceptible capacity alone that these (articulations) impart an imperceptible capacity to the sense-organ concerned, and thereby appear as causes of the manifestation (of the word-sound).”—[Ślokavārtika—eternality of words, 45].—(2173)
Kamalaśīla
The following Text sums up the position:—[see verse 2173 above]
From all this it follows that these articulations, by means of their imperceptible Capacity, produce, in the Auditory Organ, an imperceptible Capacity, and appear as the causes of manifestation—i.e. ‘of Words and Sounds’, which has to be added.—(2173)