Nyayasutra 167.4

167.4

yadi yasya vināśakāraṇaṃ nopalabhyate tad avatiṣṭhate, avasthānāc ca tasya nityatvaṃ prasajyate; evaṃ yāni khalv imāni śabdaśravaṇāni śabdābhivyaktaya iti matam, na teṣāṃ vināśakāraṇaṃ bhavatopapādyate, anupapādanād avasthānam avasthānāt teṣāṃ nityatvaṃ prasajyata iti/ atha naivam, na tarhi vināśakāraṇānupalabdheḥ śabdasyāvasthānān nityatvam iti//37//

If that whose cause of destruction is not apprehended persists, and from persistence it follows that it is eternal, then, as for these acts of hearing sound which are considered to be manifestations of sound, you cannot establish a cause of their destruction; because it is not established, they persist; and because of their persistence, it would follow that they are eternal. If that is not so, then it does not follow that sound is eternal because of its persistence due to the non-apprehension of a cause of destruction. (37)