Wheezing: A high-pitched, musical or whistling breath sound caused by airflow through narrowed lower airways, usually more prominent during expiration. It is common in asthma and COPD. Merck Manual definition

Stridor: A harsh, high-pitched sound caused by obstruction or narrowing of the upper airway such as the larynx or trachea. It is usually heard during inspiration, often without a stethoscope. New or severe stridor can indicate an airway emergency. Merck Manual description

Crepitations (crackles/rales): Discontinuous, non-musical popping or crackling sounds, usually heard during inspiration. Fine crepitations are short and high-pitched; coarse crepitations are lower-pitched and longer. They may occur with pneumonia, pulmonary edema/heart failure, atelectasis, or interstitial lung disease. Merck Manual description