Manava Dharmashastra 4.102

4.102

anilo vāyuḥ | vegena vāti vāyau vāyvantarasaṃgharṣāddhvaniḥ śrūyate yatra sa 'karṇaśravo' vāyuḥ | karṇābhyāṃ śrūyate yaḥ sa karṇaśravaḥ | sādhanakṛteti samāsaḥ | avasthāviśeṣopalakṣaṇārthaṃ karṇagrahaṇam | śrūyate karṇābhyāmeva | tena yadaivaṃ vāyuśabdaḥ śrūyate tadā nādhyetavyam |
pāṃsunsamūhati pāṃsunsamāharati pāṃsusamūhanaḥ | pāṃsurdhūliḥ | upalakṣaṇaṃ caitat, tathābhūtasya vāyorvā | yatastataśca vṛṣṭe deve yadi vāyurodṛśo vāti tāvatkālo'nadhyāyaḥ |
adhyāyajñā adhyāpanavidhijñāḥ |

Medhātithi’s commentary (manubhāṣya):
When the wind blows with force, a sound is heard, which is produced by the impact of another (contrary) wind; this is what is called the ‘air audible by the ear.’ That which is heard by the ears is called ‘audible by the ear;’ the compound being between the instrument (ear) and the noun formed by a verbal affix. The term ‘ear’ is added for the purpose of indicating a particular condition, because hearing is always by means of ears. The meaning is that ‘when the sound of wind is heard, study should not be carried on.’

‘Dust-whorl’—that which brings together dust; ‘pāṃsu’ meaning dust; this is mentioned only as indicative of the wind that produces it (i.e., the dust-storm). The meaning is that ‘after it has rained, whenever such a wind blows, that time shall be regarded as unfit for study.’

‘Versed in the rules of teaching,’—who are conversant with the rules regulating the practice of teaching.—(102)