- removal of an obstacle between the sense-faculty and its object
- an improvement (saṃskāra) of the sense-faculty grasping the object
- an improvement (saṃskāra) of the object
The first option is easily ruled out: since śabda is said by Vaiśeṣikas to be a quality of ether, it must inhere in it. Hence, there cannot ever be an obstacle between them.
The rebuttals of the second and of the third option seem less straightforward. An improvement of the sense-faculty, the Vaiśeṣika says, can occur either through the hearing-sense's being filled with the air pushed forwards by the speaker, or through its contact with it. Both cases, he continues, would suit also the thesis that śabda is produced, ``because śabda is a characteristic of ether and the hearing organ is made of ether". This short explanation does not seem to explain very much. Possibly, the Vaiśeṣika means that it is difficult to explain how could the all-pervading ether be `improved' by air in the ear, since ether has no parts. In the parallel Nyāyaśuddhi text, Śālikanātha drives a parallel with the case of sight, where the improvement of the sense-faculty consists in ``the eyes' ray's being filled with light" (ālokena […] āpyāyanaṃ cākṣuṣasya raśmeḥ). This is not possible in the case of ether and air coming from the speaker's abdomen, since ether has no parts which could be connected with it. Moreover, if it were possible, then the hearing organ would be improved once for all possible śabdas. Śālikanātha (a 9th c. Prābhākara philosopher) explains that the improvement of the sense-faculty could be twofold:
- either through removal of an hindrance, such as when one opens one's eye (and this cannot be the case, since the possibility of an obstacle to inherence has already been ruled out),
- or through the sense-faculty's being filled by something, as in the example discussed above.
Rāmānujācārya further adds, possibly for the sake of exhaustiveness, the option of the object's being improved. He has then the Vaiśeṣika rule it out as follows: ``[this would amount to] a quality of the content (viṣaya), and this cannot be. There is as a matter of fact no relationship of the internal air with a quality of ether. Even if it would be possible in some way, it would be shared also by the point of view of production (utpatti). Because it has been seen that also a relation can be, indirectly (paraṃparā), produced". This explanation points to the oddity of the relation between air and a quality of ether. However, if one juxtaposes it to the one read above, about the oddity of the relation of the partless ether with air, one is struck by the fact that no rationale explanation seems to be left to the Vaiśeṣika himself to explain how can an effort push forth air and by means of that produce a quality of ether. Does the Vaiśeṣika mean that the effort produces a quality of ether, namely śabda and, beside that, it pushes forth air?
Not exactly, since the Vaiśeṣika claims rather that the effort produces the movement of the air and that this movement produces a quality of ether, sound.