that location, hence the sound will be loudest and radiate outwardly. The pitch of a wheeze does not reliably predict the degree of narrowing in the affected airway. Stridor A special type of wheeze is stridor. Stridor — the word is from the Latin, strīdor — is a harsh, high-pitched, vibrating sound that is heard in respiratory tract obstruction. Stridor heard solely in the inspiratory phase of respiration usually indicates an upper respiratory tract obstruction, "as with aspiration of a foreign body (such as the fabled pediatric peanut)." Stridor in the inspiratory phase is usually heard with obstruction in the upper airways, such as the trachea, epiglottis, or larynx; because a block here means that no air may reach either lung, this condition is a medical emergency. Biphasic stridor (occurring during both the inspiratory and expiratory phases) indicates narrowing at the level of the glottis or subglottis, the point between the upper and lower airways. Preschool wheeze Preschool wheezing is a clinical condition that describes wheezing preschool children that do not fulfill the criteria of "asthma" fully as asthma would require a person to demonstrate a history of at least three episodes of exacerbations (worsening of symptoms) or chronic cough or wheeze for the past six months. Besides, a number of wheezing preschool children would have their symptoms resolved after they had grown up, unlike asthma which persists into adulthood. Preschool wheezing can be divided into "viral-induced wheeze" and "multi-trigger wheeze". Viral-induced wheezing accounts for about two-thirds of all preschool wheezes. The wheezing symptom is episodic and the child is completely normal in between wheezing episodes. It has a good prognosis and only supportive treatment is required. Meanwhile, multi-trigger wheezing is associated with allergy and a family history of asthma. Symptoms occur in between wheezing episodes and are likely to persist beyond early childhood. Due to difficulty in differentiating both types of wheeze, the diagnosis of viral-induced versus multi-trigger wheeze may be delayed for a period of time until its clinical course has become clear. See also Crackles (also called "crepitations" or "rales") Rhonchi Squawk (sound) References Further reading External links Audio Breath Sounds - Multiple case studies with audio files of lung sounds. R.A.L.E. Repository - sound files of breath sounds Symptoms and signs: Respiratory system