Fundamentals of Lung Sounds

Using Our Auscultation Lessons

Here we provide an example of lung sounds, a fine crackle.

Playback

Click the playback button on the torso to hear a short recording.

The patient was seated during auscultation.

Waveform

A waveform is a plot of the lung sound's amplitude over time. Click the play button to view this waveform and hear the corresponding lung sound. This video will loop until paused.

Introduction

We have selected eight important lung sounds for this introductory auscultation course. Each lesson, described below, includes a textual description, audio recording, and a waveform video. Optionally, a quiz can be taken to measure comprehension and listening skills.

Vesicular Lung Sounds

Vesicular lung sounds are the most common auscultated sounds, usually heard over most of the chest wall. These sounds are of low to moderate sound intensity (volume) with a low-pitch (200-600 Hz) with a rustling quality. During expiration, the sound intensity can diminish somewhat. The inspiration to expiration (I:E) ratio is typically 3 to 1.

Vesicular Lung Sounds - Lesson, Audio, Waveform

Bronchial Breath Sounds

Bronchial breath sounds are hollow, tubular sounds that are higher-pitched compared to vesicular sounds. They can be auscultated over the trachea and anteriorly along each side of the sternum, from the second to fourth intercostal spaces. Posteriorly, along the vertebral column from the third to sixth intercostal spaces.

The stethoscope's diaphragm should be used for these breath sounds. There is a distinct pause in the sound between inspiration and expiration. I:E ratio is 1:3.

Bronchial Breath Sounds - Lesson, Audio, Waveform

Wheeze

Air flowing through a narrowed bronchus produces wheezes. Accordingly, these sounds will have their highest sound intensity when auscultating over or near the central airways.

Wheezes are adventitious lung sounds associated with secretions, obstructions, tumors, or airway compression. They are continuous sounds with a musical quality. High-pitched wheezes have a squeaking quality, while low-pitched wheezes are similar to snoring or moaning. The proportion of the respiratory cycle occupied by the wheeze roughly corresponds to the degree of airway obstruction.

Wheezes are also classified by when they appear in the respiratory cycle, e.g. inspiratory wheezing or a late expiratory wheeze, and by additional information about the sound quality (monophonic or polyphonic). These characteristics can be found in our Intermediate Lung Sounds module.

Wheeze - Lesson, Audio, Waveform

Rhonchi

Rhonchi are continuous and low-pitched adventitious lung sounds caused by fluids or secretions in the large airways. They often have a snoring, gurgling, or rattle-like quality. They are heard primarily during expiration, but in some patients, rhonchi will also appear during inspiration. Rhonchi will usually clear or alter in sound after coughing.

Fine Crackles

Fine crackles are brief, discontinuous, popping, high-pitched breath sounds. These sounds are also similar to the sound of Velcro fasteners being pulled apart or cellophane being crumpled. Crackles can appear throughout the respiratory cycle.

Fine Crackles - Lesson, Audio, Waveform

Coarse Crackles

Coarse crackles are discontinuous, popping, or bubbling breath sounds. They are louder, lower in pitch, and of longer duration than fine crackles.

Coarse Crackles - Lesson, Audio, Waveform

Pleural Rubs

Pleural rubs are creaking or grating sounds. The sound is similar to leather against leather or walking on fresh snow on a cold day. Coughing will not alter the sound.

Pleural rubs are generated when two inflamed surfaces are sliding by one another, such as in pleurisy. During auscultation, pleural rubs can be localized to a specific point on the chest wall. These sounds occur with movement of the patient's chest and will stop when the patient holds her breath. They appear on inspiration and expiration. Should the sound continue when the patient holds her breath, it may be a pericardial friction rub.

Pleural Rubs - Lesson, Audio, Waveform

Stridor

Stridor is created by air flowing through an upper airway that is narrowed or obstructed. It occurs in 10-20% of extubated patients. Stridor is a loud, high-pitched crowing breath sound heard during inspiration. Stridor may also occur throughout the respiratory cycle, particularly if the condition worsens. Often it can be heard without a stethoscope. Causes of stridor are obstructions, pertussis, croup, epiglottis, aspirations.

Stridor - Lesson, Audio, Waveform