Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 47

Sanskrit:

नभोगुणविशेषोऽर्थो यस्य तच्छ्रोत्रमुच्यते ।वायोर्गुणविशेषोऽर्थो यस्य तत्स्पर्शनं विदु: ॥ ४७ ॥

ITRANS:

nabho-guṇa-viśeṣo ’rthoyasya tac chrotram ucyatevāyor guṇa-viśeṣo ’rthoyasya tat sparśanaṁ viduḥ

Translation:

The sense whose object of perception is sound is called the auditory sense, and that whose object of perception is touch is called the tactile sense.

Purport:

Sound is one of the qualifications of the sky and is the subject matter for hearing. Similarly, touch is the qualification of the air and is the subject of the touch sensation.