Are you ready to learn about breath sounds? I sure hope so because that is what this study guide is all about.

As a Respiratory Therapist (or student), it goes without saying that you must fully know and understand auscultation and listening to lungs sounds. The good news is — we created this study guide to help you do just that.

So if you’re ready, let’s go ahead and dive right in!

What are Breath Sounds?

Breath sounds are the noises that come from your lungs when you inhale and exhale. Any abnormality in breath sounds indicates a problem in the lungs such as:
  • Accumulation of fluid
  • Asthma
  • Chronic obstructive pulmonary disease (COPD)
  • Foreign body in the lungs or airways
  • Heart failure
  • Infection
  • Inflammation of the airways
  • Obstruction
  • Pneumonia

By listening to the quality, duration, and intensity of breath sounds, healthcare providers can come up with a proper diagnosis and medical management.

What is Auscultation?

Auscultation is a simple, non-invasive procedure that involves the use of a stethoscope to listen to the sounds produced by your body. This device can amplify the sounds within your body so that your healthcare provider can have an idea of what’s going on inside.

When performing lung auscultation, your healthcare provider places the bell or diaphragm of the stethoscope on your back and compares one side with the other. Your healthcare provider also compares the sound on the front of your chest with your back.

Types of Breath Sounds:

If your healthcare provider thinks that you might have a lung problem or an issue in your airways, the type and location of breathing sounds can give him a cue. The following are the breath sounds which can be heard using a stethoscope:

1. Vesicular (Normal)

Vesicular or normal breath sounds are usually soft and low-pitched and are heard during auscultation of the chest and lung surface of a healthy person. The sound has a rustling quality during inspiration. This is generated by turbulent airflow within the lobes of the lungs.

During expiration, the sound becomes softer as air flows within the larger airways. The inhalation process is normally 2-3 times the length of the exhalation process.

2. Crackles (Rales)

Crackles, also known as rales, are short, explosive, nonmusical sound and are audible in a lung field that has fluid in the small airways. Crackles can occur either when you inhale or exhale but are more common during the inspiratory phase. It can be classified as fine and coarse. The difference between the two is that fine crackles have a higher frequency and a shorter duration and are caused by sudden opening of a narrowed or closed airway. The sound of fine crackles can be compared to that of salt heated on a frying pan.

Coarse crackles, on the other hand, are louder, lower in pitch and last longer, and are caused by secretions. The sound of course crackles is like pouring water out of a bottle. Crackles are often associated with lung inflammation or infection. If they do not clear after a cough, this may indicate fluid in the alveoli, acute respiratory distress syndrome, or pulmonary fibrosis.

3. Wheezes

Wheezes are defined as continuous musical tones that commonly occur at the end of the inspiratory phase or early expiratory phase as a result of the gradual opening or closing of a collapsed airway. Wheezes are either high-pitched or low-pitched. They sound like a whistle when you breathe and are most audible during the expiratory phase.

Aside from narrowed airways, wheezes can also be caused by inflammation secondary to asthma and bronchitis.

4. Rhonchi

Rhonchi are now called a sonorous wheeze because their sound can be compared to snoring or gurgling. These lung sounds are often low-pitched and are audible during the expiratory phase. The main difference between rhonchi and wheezes is that rhonchi are low and dull while wheezes are high and squeaky. Rhonchi are mainly caused by airway obstruction including accumulation of mucus secretions, lesions, or foreign bodies.

Certain medical conditions such as pneumonia, chronic bronchitis, and cystic fibrosis can also cause rhonchi.

5. Stridor

Stridor, also known as “noisy breathing”, is a high-pitched sound caused by airway obstruction. This sound is commonly heard during the inspiratory phase but can also be present during the expiratory phase. If heard during inhalation, the airway obstruction is typically at the level of the vocal cords or just below the windpipe. If heard during exhalation, the airway obstruction might be in the lower trachea or the bronchi.

Several medical conditions can cause stridor including vocal cord abnormality, narrowing of the larynx (voice box), abnormal growth of blood vessels, lesions, infection, and foreign bodies.

6. Pleural friction rubs

Pleural friction rubs are creaking or grating sounds. Because these sounds occur whenever the chest wall moves, they are generally heard throughout inhalation and exhalation. This lung sound is almost always associated with inflammation of serous membrane lining in the thorax known as pleurae.

As the name implies, pleural friction rubs sound like two objects rubbing against each other or walking on fresh snow. Other medical conditions such as pneumonia and pulmonary embolism can also cause pleural friction rubs.

What are Vesicular Breath Sounds?

Vesicular breath sounds are normal breath sounds that are low-pitched with a rustling quality. They can be heard as a soft noise during inhalation and slowly gets softer as you exhale. These sounds are normally audible throughout most of the lung fields. The inspiratory component predominates and is 2-3 times longer than the expiratory phase.  

What are Adventitious Breath Sounds?

Adventitious breath sounds are abnormal sounds that occur over the lungs and airways. The term “adventitious” breath sounds describe the additional audible lung sounds during auscultation.  These include abnormal lung sounds such as crackles (rales), wheezes, rhonchi, stridor, and pleural friction rubs.

Adventitious breath sounds are commonly associated with a wide array of heart and lung conditions. The type, duration, location, and intensity of each adventitious breath sounds can help the healthcare provider determine the root cause of the medical condition.

Causes of Abnormal Breath Sounds:

There are several causes of abnormal breath sounds. Each of which are specific to the type of breath sounds a patient is experiencing:

  • Air moving through narrowed airways due to swelling or obstruction causes wheezes.
  • Airway obstruction due to the accumulation of mucus secretions, lesions, or foreign bodies causes rhonchi.
  • Fluid accumulation in the small airways or atelectasis (lung collapse) causes crackles.
  • Obstruction of the upper airway causes stridor.
    Rubbing of inflamed pleural surfaces against each other during respiration causes pleural friction rub.

In addition to this, certain lung and heart problems can also cause abnormal breath sounds.

Treatment for Abnormal Breath Sounds

If you are experiencing continuous abnormal breathing sounds, you should consult with your doctor for proper diagnosis and medical management. Abnormal breath sounds are often associated with common and treatable medical conditions. However, these sounds can also indicate an underlying disease.

The following are the common therapeutic strategies for abnormal breath sounds:

1. Metered-Dose Inhaler (MDI)

This is a pressurized inhaler that delivers a bronchodilator (dilates the airways), corticosteroid (suppresses inflammation) or a combination of both. By opening the airways and suppressing the inflammatory process, it can help restore breath sounds to normal.

2. Nebulizer

This delivers aerosolized form of medications into the alveoli via inhalation. This treatment adds moisture to the respiratory system, which in turn improves clearance of pulmonary secretions. Nebulizers also help improve breath sounds by dilating the airways.

3. Incentive spirometry

This is a simple, inexpensive and effective tool for achieving a normal lung function. This device mimics natural sighing or yawning, which in turn improves lung expansion and gas exchange. To use the device, you need to place the mouthpiece spirometer in your mouth and do deep breathing exercises.

4. Chest physiotherapy (CPT)

This is also considered a simple and effective method of achieving normal breath sound. CPT includes various techniques in order to naturally clear lung secretions through the use of vibration or shaking, proper positioning, breathing exercises, and coughing techniques.

5. Antibiotics

Antibiotic therapy is designed to fight infection and destroy microorganisms that affect lung function. This treatment strategy can also help clear airway inflammation and mucus secretions.

What are Bronchial Breath Sounds?

Bronchial breath sounds are tubular, hollow sounds produced during the inspiratory and expiratory phase as a result of abnormal increase in the transmission of airway sounds to the chest surface. The sound is very similar to the sound produced by blowing to a hollow tube. They are audible upon auscultation of the large airways and have a higher pitch compared to vesicular breath sounds.

The expiratory phase of bronchial breath sounds is shorter and there is no pause between inhalation and exhalation.

What are Bronchovesicular Breath Sounds?

Bronchovesicular breath sounds are normal sounds heard in the mid-chest area or over the shoulder blade (scapula). Unlike other normal breath sounds, bronchovesicular breath sounds have tubular quality. These sounds are the combination of bronchial breath sounds heard near the trachea and vesicular sound in the alveoli.

Bronchovesicular breath sounds have equal periods of inhalation and exhalation (ratio is 1:1). However, the differences in pitch and intensity are often audible during the expiratory phase.

What are Diminished Breath Sounds?

Diminished breath sounds, also known as diminished vesicular sounds, are soft, distant lung sounds of lower intensity. These sounds are normally heard in patients with decreased air volume, such as in critically ill and obese patients, and those with increased muscle mass, air or fluid around the lungs, increased chest wall thickness, and lung hyperinflation. The ratio of the inspiratory phase to the expiratory phase is 3:1.

When are Coarse Breath Sounds Heard?

Coarse breath sounds are actually a type of crackles/rales. These sounds are clicking, bubbling, or rattling sounds that occur during the inspiratory process when air opens closed spaces in the lungs. Coarse breath sounds are louder, low-pitched and have longer duration.

Most patients with copious amounts of secretions exhibit coarse breath sounds during auscultation of the affected lung area.  

When are Pneumonia Breath Sounds Heard?

Pneumonia is a respiratory infection caused by harmful microorganisms and is characterized by a productive cough, often with greenish to yellowish mucus secretions. If you have pneumonia, your healthcare provider may hear crackling, bubbling, or rumbling sounds as well as wheezing in some areas of your chest during auscultation.

Crackles in patients with pneumonia are often heard only on one side of the chest or when lying down. In addition to crackles and wheezes, low-pitch lung sounds called rhonchi are also audible during the expiratory phase in patients with pneumonia.

What are Stridor Breath Sounds?

Stridor is a high-pitched lung sound created by airway obstruction and is mostly audible during inhalation but can also be heard during exhalation in patients with deteriorating condition. These sounds commonly occur in extubated patients as a complication of endotracheal intubation.[i] In children, stridor is very audible when lying on the back (supine position).

Common causes of stridor are croup, pertussis, aspirations, epiglottis, choking, severe shock (anaphylactic shock), tonsillitis, laryngitis, lung cancer, deviated septum, and blood transfusion reactions.

How to Perform Auscultation?

In order to assess breath sounds, your healthcare provider performs auscultation using a stethoscope. This technique is commonly used to examine the heart and lungs but can also be used in the abdomen and body areas with major blood vessels.

The following are the steps in performing a proper auscultation:

  1. Explain the procedure to the patient to establish trust and rapport.
  2. Stand close to the patient to gain access to the target body part.
  3. Place the eartips of the stethoscope in your ears and adjust them as desired.
  4. Use the diaphragm (flat part at the end of the tubing which has a thin plastic) to check for high-pitched sounds.
  5. Use the bell (smaller, round device attached to the diaphragm) to check for low-pitched sounds.
  6. Hold the diaphragm or bell firmly against the patient’s skin with enough pressure (must have a round mark on the skin after placement to ensure high quality sounds).
  7. Listen to the sounds and try to identify their intensity, location, strength, pattern, and duration.
  8. Locate normal and abnormal sounds by gliding the diaphragm or bell over the body area.
  9. Compare one side with the other (e.g. compare the sound on the front of the patient’s chest with his or her back).
  10. Document the findings.

Practice Questions about Breath Sounds for Respiratory Therapy Students:

1. What are fine crackles?
They are high-pitched, discrete, discontinuous crackling sounds heard during the end of respiration; not cleared by a cough.

2. What are medium crackles?
They are lower, moist sound heard during the mid-stage of inspiration; not cleared by a cough.

3. What is rhonchi (sonorous wheezing)?
They are loud, low, coarse sounds like a snore most often heard continuously during inspiration or expiration; coughing may clear sound (usually means mucus accumulation in trachea or large bronchi).

4. What are coarse crackles?
They are loud, bubbly noise heard during inspiration; not cleared by a cough

5. What are wheezes?
They make a musical noise sounding like a squeak; most often heard continuously during inspiration or expiration; usually louder during expiration.

6. What is a pleural friction rub?
It is a dry, rubbing, or grating sound, usually caused by inflammation of pleural surfaces; heard during inspiration or expiration; loudest over the lower lateral anterior surface.

7. What is stridor?
Harsh or high-pitched respiratory sound, caused by an obstruction of the air passages.

8. What are vesicular breath sounds?
They are heard over most lung fields; low pitch; soft and short expirations; more prominent in a thin person or a child, diminished in the overweight or very muscular patient.

9. What are bronchovesicular breath sounds?
They are heard over the main bronchus area and over upper right posterior lung field; medium pitch; expiration equals inspiration.

10. What are bronchial breath sounds?
They are heard only over the trachea; they have a high pitch; loud and long expirations, sometimes a bit longer than inspiration.

11. What is auscultation?
Listening to sounds of the body with the aid of a stethoscope.

12. Where will bronchovesicular breath sounds be heard?
Around the sternum or center of the chest.

13. What sound would you hear with a pleural effusion?
Decreased or absent breath sounds.

14. What do fine crackles sound like?
The make a popping sounds; they are higher pitched.

15. What do coarse crackles sound like?
Bubbling/rumbling, discontinuous, not as sharp as fine crackles.

16. What should be noted when listening to crackles?
The location of sound, duration, pitch, and when the sound occurs (inspiration or expiration).

17. What is the mechanical main cause of crackles?
The small airways open during inspiration and they collapse during expiration; or, air bubbles going through secretions or incompletely closed airways during expiration.

18. What does a wheeze sound like?
Continuous, high pitched, hissing sound; they tend to be longer than crackles and they occur on expiration.

19. What does rhonchi sound like?
It has a much lower pitch than a wheeze. It tends to be longer than crackles.

20. What does rhonchi normally imply?
That there is an obstruction of a larger airway by secretions.

21. What makes stridor sound different than others sounds?
It can usually be heard without a stethoscope.

22. If stridor does exist, what does it mean?
It means that there is a medical emergency that requires immediate attention.

23. What does a pleural rub sound like?
Brushing, similar to coarse crackles (The patient will be in pain, and be able to localize it to where the sound can be heard).

24. What is the mechanical main cause of a pleural rub?
The pleural surfaces are inflamed or roughened and are rubbing each other.

25. How should a patient be positioned before auscultation?
They should preferably be sitting up. Ensure they are not leaning against anything.

26. What are the normal breath sounds?
Tracheal, Vesicular, Bronchial, and Bronchovesicular.

27. Breath sounds can be classified into what three categories?
Normal, Abnormal, and Adventitious

28. What are bronchovesicular breath sounds?
Heard over the main bronchus are and upper right posterior lung fields. Intermediate in intensity and pitch, expiration equals inspirations. Normally heard in the 1st and 2nd intercostal spaces.

29. What are vesicular breath sounds?
Vesicular breath sounds are soft and low pitched, consist of a quiet, wispy inspiratory phase followed by a short, almost silent expiratory phase. They are heard over most of the lung fields. More prominent in children and thin adults.

30. What are the abnormal breath sounds?
Rales, Crackles, Rhonchi, Wheezes, and Absent.

31. What are the adventitious (abnormal) breath sounds?
Crackles, Rales, Rhonchi, Wheeze, Pleural friction rub.

32. What are fine crackles?
Crackles are discontinuous explosive, popping sounds that originate in the airways. Crackles are heard more commonly during inspiration than expiration. They are not cleared with a cough.

33. What are wheezes?
Wheezes are commonly heard at the end of inspiration and beginning of expiration. They result as a collapsed airway lumen gradually opens during inspiration or gradually closes during expiration. Wheezes are significant since they imply decreased airway lumen diameter either due to thickening of reactive airway walls or collapse of airways due to surrounding pulmonary disease.

34. What is stridor?
Stridor is intense continuous monophonic wheezes heard loudest over extrathoracic airways. These are typically heard over the trachea and are considers significant and indicate an upper airway obstruction

35. What is stertor?
Is a poorly defined and inconsistently used term to describe harsh discontinuous crackling sounds over the larynx or trachea. It may be sonorous snoring sound heard over extra-thoracic airways.

36. What is a pleural friction rub?
Dry rubbing or grating sound, usually caused by inflammation of the pleural surfaces, heard during inspiration and expiration. Loudest over lower lateral anterior surface

37. What are the 3 types of NORMAL breath sounds?
Vesicular, Bronchovesicular, and Bronchial.

38. What are bronchial breath sounds?
Heard only over the trachea, loud and high pitched, with long expiration, sometimes a bit longer than inspiration.

39. What is the sequence of steps in the examination of the chest and lungs?
Inspection, Palpation, Percussion, then Auscultation.

40. What is the difference in medium crackles and coarse crackles?
Medium crackles are lower, more moist, and are heard during the mid-stage of inspiration; they are not cleared with a cough. Coarse crackles are loud, bubbly noise heard during inspiration; also, they are not cleared with a cough.

Final Thoughts

So there you have it. That wraps up our massive study guide on breath sounds and auscultation. I hope that this information was helpful for you. Again, knowing the ins and outs of everything the do with breath sounds is (obviously) very important for Respiratory Therapists and RT students. And I hope this guide can help you gain the knowledge that you need.

Thank you so much for reading and as always, breathe easy my friend.