Stridor may be heard in patients with vocal cord dysfunction, epiglottitis, airway edema, anaphylaxis, laryngotracheitis, extrinsic compression of the trachea, or a foreign body.Ĥ) Squawk, also known as “squeak,” is a mixed sound consisting of short wheezes accompanied by crackles that are heard in the middle to the end of inspiration. This sound is caused by large airway narrowing and may indicate obstruction of the larynx or trachea. Of note, localized wheeze may be due to a focal process, including a tumor, foreign body, or mucous plug.ģ) Stridor is a particularly loud, high-pitched, continuous sound, more clearly heard on inspiration over the upper airways or sometimes even without a stethoscope. Expiratory wheeze is mostly caused by narrowing of the airways within the chest, which can occur in the setting of asthma, chronic obstructive pulmonary disease, aspiration of gastric contents, or heart failure. Wheezes (hissing, whistling sounds) are produced by the turbulent flow of air through narrowed airways, while rhonchi are mainly caused by secretions present in the airways. In patients with upper airway obstruction, tracheal sounds may become musical and can present as either stridor or localized wheeze.ġ) Crackles are nonmusical, short (0.25 seconds), which may be high-pitched (wheezes) or low-pitched (rhonchi) and are generally audible during expiration. Pathologic tracheal or “bronchial” sounds are audible over peripheral lung areas and may suggest lung consolidation (due to inflammation, infection, hemorrhage, protein, or malignancy).

Impaired transmission of sounds may be due to the presence of fluid or air in the pleural space, consolidated lung, large bullae in patients with emphysema, or by chest wall deformities or obesity.Ģ) Normal tracheal sounds are hollow nonmusical sounds with a wide spectrum of frequencies that are clearly heard at the suprasternal notch or the lateral neck in both respiratory cycles. Decrease in sound generation may be due to impaired respiratory drive or impaired flow of air to the peripheral airways (foreign body or obstructive airway diseases). In disease states, there may be diminished intensity due to decreased generation of sound energy, impaired sound transmission, or both. They are produced by turbulent air flow through lobar and segmental bronchi. Authors: Wojciech Szczeklik, Miłosz Jankowskiġ) Normal lung or “vesicular” sounds are soft, nonmusical, and audible over almost entire peripheral lung zones during inspiration and early expiration.

Types of lung sounds