Breath sounds are classified as bronchial, vesicular, or bronchovesicular. Bronchial sounds (also called tubular sounds) normally arise from the tracheobronchial tree and vesicular sounds normally heard over lung parenchyma. Loud, harsh, and high pitched bronchial sounds are typically heard over the trachea or at the right apex. If heard in other areas of the lung, bronchial sounds are abnormal. In contrast, vesicular breath sounds are soft, low pitched, predominantly inspiratory, and appreciated especially well at the posterior lung bases. Bronchovesicular sounds can be heard during inspiration and expiration and have a mid-range pitch and intensity. They are commonly heard over the upper third of the anterior chest. Terms high and low pitch are defined by the American Thoracic Society Committee as 400hz or greater and 200hz or less, respectively.

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