What Does a Heart Murmur Sound Like? 

You may have heard the term “heart murmur”, but would you recognize a heart murmur sound if you heard it? Is it a soft whoosh, a sharp click, or something in between? These sounds can reveal more than you might expect—if you know what to listen for. So, what does a heart murmur sound like? The answer might surprise you.

Schedule an appointment for cardiology care to diagnose murmurs.

What Causes a Heart Murmur and How Does It Sound?

While some murmurs are harmless, others may signal serious heart conditions. Heart murmurs can originate for many reasons. Below are the most common causes, grouped by category:

1. Heart Valve Problems

Stenosis	The valves narrow, limiting the normal flow of blood.
Valve insufficiency	The valves don’t close properly, allowing blood to flow backward.

2. Congenital heart defects

Ventricular septal defect (VSD)

An abnormal opening between the heart’s ventricles that allows blood to pass between them.

3. Acquired heart diseases

High blood pressure	Increases pressure on the valves and blood vessels, creating turbulence.
Endocarditis	Infection of the inner lining of the heart that can damage the valves.
Dilated cardiomyopathy	The heart muscle weakens and enlarges, affecting blood flow.
Hypertrophic cardiomyopathy	The heart muscle thickens, making it harder to pump blood efficiently.

4. Physiological (non-pathological) factors

These can cause functional murmurs, meaning murmurs not related to structural heart problems.

• Pregnancy: Increased blood volume can lead to temporary turbulence.
• Fever: Accelerated heart rate and blood flow can produce unusual sounds.
• Anemia: Reduced red blood cells can cause increased flow, resulting in extra sound.

Recognizing the Sound of a Heart Murmur

A heart murmur is an extra sound heard during the heartbeat, such as a soft hiss or whisper, that accompanies or disrupts the normal “lub-dub” rhythm. Murmurs are classified based on when they occur in the heart cycle:

Systolic	During the heart’s contraction	Sounds like a “sshh” between the first and second heart sounds.
Diastolic	During the heart’s relaxation	Occurs after the second sound, like a soft or sharp “whoosh.”
Continuous	Heard throughout the entire heart cycle	Present in both phases without interruption.

Murmur intensity is measured on a scale from 1 to 6:

1/6	Very hard to hear, even for experienced professionals.
2/6	Faint, but audible to trained practitioners.
3/6	Moderately loud; begins to raise concern.
4/6	Loud; may be accompanied by a palpable vibration (thrill).
5/6	Very loud; heard easily with minimal contact.
6/6	Extremely loud; audible without a stethoscope.

Differentiating Between a Normal and Abnormal Murmur

Not all heart murmurs are a sign of disease. Some are completely harmless, while others may point to a more serious condition. Knowing the difference helps guide appropriate evaluation.

Characteristic	Functional Murmur	Pathological Murmur
Intensity	Soft	Moderate to strong
Frequency	Low	High or variable
Symptoms	None	Yes—may include shortness of breath, fatigue
Cause	Fast but normal blood flow	Structural or valve abnormality
Requires treatment	No	Usually yes
Resolves over time	May go away	Tends to persist or worsen

Correctly identifying the murmur type helps determine whether it’s a normal variation in blood flow or a warning sign.

Describing the Sound of a Pathological Heart Murmur

A pathological heart murmur is an extra sound heard between normal heartbeats, usually indicating abnormal blood flow. This turbulence is often caused by structural issues, such as problems with heart valves or areas near the heart.

Whispers or soft hissing

One of the most common types sounds like a soft hiss or prolonged whisper. This occurs when blood flows abnormally through a valve that doesn’t open or close correctly:

• shhhh…
• whoosh…

Harsh or creaky sound

If turbulence is more intense, the murmur may sound harsh or even creaky, suggesting greater resistance or a more serious defect:

• grrrrr…
• creeeek…

These sounds may indicate conditions like valve stenosis (narrowing) or insufficiency (leaking).

Clicking Sound

Sometimes, especially with abnormal or calcified valves, a brief metallic click may be heard before or after the murmur. This can help identify specific valve conditions.

A pathological murmur typically stands out due to its unusual, consistent tone. Hearing a hiss, whisper, harsh sound, or click outside the usual heartbeat pattern warrants further evaluation.

Heart Murmur Sound at Different Stages

In a healthy heart, the typical sound pattern is “lub-dub”, created by the closing of the heart valves.

Additional sounds shouldn’t normally be present. When a murmur is detected, it usually disrupts this natural rhythm.

Murmur sound by stage

Systolic murmur

• When: Between the first and second heart sounds (S1 and S2)
• Example: Lub – sshhh – Dub
• Likely cause: Aortic stenosis, mitral insufficiency
• Sound pattern: May be diamond-shaped if it peaks mid-systole

Diastolic murmur

• When: After the second sound (S2), during the heart’s filling phase
• Example: Lub – Dub – shhhh
• Likely cause: Aortic insufficiency, mitral stenosis
• Sound pattern: Often starts loudly then fades (especially with semilunar valves)

Continuous murmur

• When: Throughout the heart cycle without pause
• Likely cause: Patent ductus arteriosus or other abnormal vessel connections

Recognizing a murmur’s stage, tone, and intensity helps identify its likely origin, such as stenosis, insufficiency, or structural anomalies.

Detecting Heart Murmurs with a Stethoscope

Using a stethoscope is a primary technique for identifying abnormal heart sounds, known as murmurs. The process starts by placing the stethoscope over different chest areas that align with the heart valves, listening for unusual sounds during the heartbeat.

During evaluation, the healthcare professional considers several elements: murmur intensity, timing, location, and changes with breathing or body position. If a murmur is detected, further diagnostic tests like echocardiograms, ECGs, or chest X-rays are often used.

Some murmurs are discovered incidentally during routine check-ups and turn out to be functional, meaning they aren’t tied to any heart disease. Even so, listening with a stethoscope remains an essential way to catch possible changes in heart structure or function early.

Sources:

• Ware, W. A., Bonagura, J. D., & Scansen, B. A. (2021). Murmurs and abnormal heart sounds. In Cardiovascular Disease in Companion Animals (pp. 225-236). CRC Press.
• Costandache, M. A., Cioată, M. A., & Iftene, A. (2023). Automated heart murmur detection using sound processing techniques. Procedia Computer Science, 225, 2961-2970.