- Wheezing is the hallmark auscultatory finding in asthma due to bronchial smooth muscle constriction, inflammation, and mucus production, causing airway narrowing and turbulent airflow.
- This leads to the characteristic musical, high-pitched sound most prominent during expiration.
- Dyspnoea in asthma correlates with airway obstruction, and wheezing reflects this physiological change, making it the most typical sign.
- Other sounds like coarse crackles or pleural rub are not characteristic of asthma and suggest alternative diagnoses. 
- Bronchial breath sounds indicate lung consolidation, not airway obstruction.

Reference: Davidson’s Principles and Practice of Medicine, 24th Edition, Chapter: Diseases of the Respiratory System, Page 622.