Respiratory sounds

Respiratory sounds, also known as lung sounds or breath sounds, refer to the specific sounds generated by the movement of air through the respiratory system. These may be easily audible or identified through auscultation of the respiratory system through the lung fields with a stethoscope as well as from the spectral characteristics of lung sounds. These include normal breath sounds and adventitious or "added" sounds such as crackles, wheezes, pleural friction rubs, stertor, and stridor. Description and classification of the sounds usually involve auscultation of the inspiratory and expiratory phases of the breath cycle, noting both the pitch (typically described as low (≤200 Hz), medium or high (≥400 Hz)) and intensity (soft, medium, loud or very loud) of the sounds heard. Normal breath sounds are classified as vesicular, bronchovesicular, bronchial or tracheal based on the anatomical location of auscultation. Normal breath sounds can also be identified by patterns of sound duration and the quality of the sound as described in the table below: Common types of abnormal breath sounds include the following: Rales: Small clicking, bubbling, or rattling sounds in the lungs. They are heard when a person inhales. They are believed to occur when air opens alveoli. Rales can also be described as moist, dry, fine, and coarse. Rhonchi are coarse rattling respiratory sounds, usually caused by secretions in bronchial airways. The sounds resemble snoring. "Rhonchi" is the plural form of the singular word "rhonchus". Stridor: Wheeze-like sound heard when a person breathes. Usually it is due to a blockage of airflow in the windpipe (trachea) or in the back of the throat. Wheezing: High-pitched sounds produced by narrowed airways. They are most often heard when a person breathes out (exhales). Wheezing and other abnormal sounds can sometimes be heard without a stethoscope. Pectoriloquy, egophony and bronchophony are tests of auscultation that utilize the phenomenon of vocal resonance.