Does Size Matter? March 26 2015

Does Size Matter? 

Huh? What we mean is, does the length of your stethoscope tubing affect the sound quality of your Stethoscope? The answer is not as clear as one would think. Littmann offers a short tube option to many of their stethoscopes including the Littmann Cardiology III Stethoscope and the Littmann Master Cardiology Stethoscope. We guess a better way of asking that questions is “What is the advantage of having a short tube stethoscope?” 

The best way to answer this is in the form of a comparison. Compare the length of a stethoscope tube to a garden hose. The longer the length of a garden hose, the less pressure at the end of the hose. This is due to frictional and other internal forces and the same idea can go for the tube of a stethoscope. The sound from the bell has to travel the entire length of the tube to reach the ears, which bounces many times, slowing down after each time. For a stethoscope, the difference in acoustic pressure is not noticeable by the human ear. The difference is so small, you will never notice and it will not affect your ability to diagnose. That being said, there is an advantage since resonant frequency decreases as tubing length increases. This provides a better response to the lower frequency sounds as it has been shown that the human ear is not as sensitive to low frequency sounds. Thus any improvement to those frequencies can be a big advantage. Again, these differences are so small, the human ear cannot distinguish a difference.

So, when choosing a stethoscope, size DOES matter (WE KNEW IT!!!) but not in regards to the sound quality. Look at it this way, if you purchase a Littmann Cardiology III Stethoscope in a 22” Tube, it will put you 5” closer to the patient then the standard 27” tube. Many professionals appreciate the additional 5” when dealing with sick patients especially. The longer tube also allows less bending which causes stress on the lower back.