A respiratory system and chest symptom that is characterized by a sound of breathing that is not similar to that of the sound of moving air and may include: rhonchi (a low-pitched breath sound), crackles (a high-pitched breath sound), wheezing (a high-pitched whistling sound caused by narrowing of the bronchial tubes), and stridor (a harsh, vibratory sound caused by narrowing of the upper airway). [ url:https://www.healthline.com/health/breath-sounds#types ]