Which respiratory condition is characterized by a wheezing sound?

A wheezing sound is typically indicative of narrowed airways, which is a hallmark of asthma. In asthma, the muscles around the airways tighten, leading to inflammation and increased mucus production. This results in a high-pitched whistling or wheezing sound as air passes through the constricted passages during breathing, particularly on expiration.

While bronchitis can cause wheezing due to inflammation and mucus buildup, it primarily presents with a cough and can have a different sound pattern, often involving more of a rattling quality than the definitive wheezing associated with asthma. Pneumonia, on the other hand, is characterized by fluid in the lungs leading to symptoms like cough, fever, and difficulty breathing, but not specifically wheezing. Emphysema, a type of COPD, can feature wheezing as well, yet it is more associated with a prolonged exhalation phase and less reactive airway constriction compared to asthma.

Thus, the clear association of wheezing with bronchoconstriction and airway spasms makes asthma the correct condition related to the wheezing sound.