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 Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope. Auscultation is performed for the purposes of examining the circulatory and respiratory systems (hea ...

of the

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

through the lung fields with a

stethoscope The stethoscope is a medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, and one or two tubes connected to two earpieces. ...

as well as from the spectral characteristics of lung sounds. These include normal breath sounds and adventitious or "added" sounds such as

crackles Crackles are the clicking, rattling, or crackling noises that may be made by one or both lungs of a human with a respiratory disease during inhalation. They are usually heard only with a stethoscope ("on auscultation"). Pulmonary crackles a ...

wheeze A wheeze is a continuous, coarse, whistling sound produced in the respiratory airways during breathing. For wheezes to occur, some part of the respiratory tree must be narrowed or obstructed (for example narrowing of the lower respiratory tract ...

pleural friction rub A pleural friction rub, or simply pleural rub, is an audible medical sign present in some patients with pleurisy and other conditions affecting the chest cavity. It is noted by listening to the internal sounds of the body, usually using a stethosco ...

s, stertor, and

stridor Stridor (Latin for "creaking or grating noise") is a high-pitched extra-thoracic breath sound resulting from turbulent air flow in the larynx or lower in the bronchial tree. It is different from a stertor which is a noise originating in the pha ...

. Description and classification of the sounds usually involve

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

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:

Abnormal breath sounds

Common types of abnormal breath sounds include the following:

Continued

*Rales: Small clicking, bubbling, or rattling sounds in the lungs. They are heard when a person breathes 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.

Other tests of auscultation

Pectoriloquy Pectoriloquy is the increased resonance of the voice through the lung structures, so that it is clearly comprehensible using a stethoscope on the chest. It usually indicates consolidation of the underlying lung parenchyma. Types include egophony ...

egophony Egophony (British English, aegophony) is an increased resonance of voice sounds heard when auscultating the lungs, often caused by lung consolidation and fibrosis. It is due to enhanced transmission of high-frequency sound across fluid, such as in ...

and

bronchophony Bronchophony is the abnormal transmission of sounds from the lungs or bronchi. Bronchophony is a type of pectoriloquy. It is a general medical sign detected by auscultation. Technique The patient is requested to repeat a word several times while ...

are tests of

that utilize the phenomenon of

vocal resonance Vocal resonance may be defined as "the process by which the basic product of phonation is enhanced in timbre and/or intensity by the air-filled cavities through which it passes on its way to the outside air." Throughout the vocal literature, various ...

. Clinicians can utilize these tests during a physical exam to screen for pathological lung disease. For example, in

whispered pectoriloquy Whispered pectoriloquy refers to an increased loudness of whispering noted during auscultation with a stethoscope on the lung fields on a patient's torso. Usually spoken sounds of a whispered volume by the patient would not be heard by the clini ...

, the person being examined whispers a two syllable number as the clinician listens over the lung fields. The whisper is not normally heard over the lungs, but if heard may be indicative of

pulmonary consolidation A pulmonary consolidation is a region of normally compressible lung tissue that has filled with liquid instead of air. The condition is marked by induration (swelling or hardening of normally soft tissue) of a normally aerated lung. It is conside ...

in that area. This is because sound travels differently through denser (fluid or solid) media than the air that should normally be predominant in lung tissue. In egophony, the person being examined continually speaks the English long-sound "E" ( /i/). The lungs are usually air filled, but if there is an abnormal solid component due to infection, fluid, or tumor, the higher frequencies of the "E" sound will be diminished. This changes the sound produced, from a long "E" sound to a long "A" sound ( /eɪ/).

History

In 1957, Robertson and Coope proposed the two main categories of adventitious (added) lung sounds. Those categories were "Continuous" and "Interrupted" (or non-continuous). In 1976, the International Lung Sound Association simplified the sub-categories as follows: :Continuous ::Wheezes (>400 Hz) ::Rhonchi (<200 Hz) :Discontinuous ::Fine crackles ::Coarse crackles Several sources will also refer to "medium" crackles, as a crackling sound that seems to fall between the coarse and fine crackles. Crackles are defined as discrete sounds that last less than 250 ms, while the continuous sounds (rhonchi and wheezes) last approximately 250 ms. Rhonchi are usually caused by a stricture or blockage in the upper airway. These are different from

References

External links

Audio Breath Sounds
- Multiple case studies with audio files of lung sounds.

- sound files of breath sounds

- Respiratory auscultation with audio examples * * Lehrer, Steven. Understanding Lung Sounds. Elsevier 2002.
Lung Sounds
- 20 recordings and waveforms {{Physical exam Symptoms and signs: Respiratory system Pulmonology