As you hone in on a sound during auscultation, it’s natural for you to toggle back and forth between hearing low and high frequency sounds with your stethoscope to make sure you’re hearing the sound you want to hear, accurately. Did you know you can hear both low and high frequency sounds without moving the placement of your stethoscope chestpiece? It’s called tunable technology.
Tunable technology was invented by 3M in the mid-1980s to upgrade traditional stethoscopes that had a diaphragm side for high frequency sounds and an open bell for low frequency sounds. If you own a 3M™ Littmann® Stethoscope*, your stethoscope may have one or two tunable diaphragms on the chestpiece, allowing you to switch back and forth between hearing low and high frequency sounds by simply changing the amount of pressure applied to the chestpiece.
The arrival of tunable diaphragms meant clinicians no longer had to flip back and forth between the diaphragm and open bell. This innovation also enabled today’s 3M stethoscopes to have an adult side and a pediatric side that both have tunable technology, adding to the versatility of your stethoscope.
Tunable diaphragms help ensure the full-range of sound frequency is heard. Use light pressure to emphasize low-frequency sounds (e.g. the lub dub of the heart) and firm pressure to emphasize high-frequency sounds (e.g. the whooshing characterized by an ejection murmur). By applying firmer pressure, you can block out the bass. See how it works.
Knowing how to apply the right amount of pressure for the frequency you’re targeting is essential. You need to strike a balance between pushing hard and backing off. It’s intuitive that when you want to hear something deeper, you’re going to press harder. Whereas, low frequency or low pressure is harder to refine. To hear low frequency sounds with a tunable diaphragm, you don’t want to apply any amount of pressure (no indentation on the patient’s skin). The most common mistake clinicians make is to put the chestpiece on the patient and apply too much pressure when trying to hear low frequency sounds. Here’s a general rule of thumb: Make good contact with the patient’s skin, but don’t apply any pressure beyond initial contact.
Clinicians tell us they're leveraging tunable technology during patient auscultation without even realizing it. Once they see a demonstration, there's an aha moment when they realize how to get the most out of their stethoscope. The benefits of tunable technology include:
When combined with advanced auscultation skills, tunable technology can provide clinicians a more convenient, consistent and versatile listening experience.
*3M Littmann Classic II Pediatric and Infant Stethoscopes do not have tunable diaphragms.