What is a tunable diaphragm stethoscope?

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Tunable diaphragms are excellent to easily switch from low and high-frequency sounds without the need of switching from bell to diaphragm modes. 

In this article, we will go through this technology. Still, to better understand this innovation brought by 3M to the stethoscope world, it is critical to understand what the diaphragm is and how it works.

How does a diaphragm work?

The diaphragm is a sealed membrane that vibrates in the same way that your eardrum does. When it occurs, the column of air inside the stethoscope tube travels up and down, causing air to flow in and out of your ear canal and to hear sound. 

Because the surface area of the diaphragm is significantly bigger than the surface area of the column of air that it moves in the tube, the air in the tube must travel further than the diaphragm, causing the pressure waves that exit the ear tip to be magnified. 

Larger pressure waves produce louder sounds in your ear. Sound is amplified in this way using stethoscopes.

A separate bell and diaphragm are standard features of stethoscopes. The bell best conveys low-frequency sounds, whereas the diaphragm is best at transferring high-frequency sounds. 

Some stethoscopes incorporate these capabilities onto a single surface called a tunable diaphragm.

What is a tunable diaphragm?

Tunable diaphragm technology was initially invented and patented by 3M. 

Tunable diaphragm technology improves the efficiency of auscultation. Clinicians can isolate each frequency band to hear small noises by altering the pressure applied to the chest piece.

Low-frequency may be heard by applying light pressure, but firm pressure restricts the movement of the diaphragm membrane, blocks low-frequency sounds, and allows higher-frequency sounds to be heard. 

Furthermore, tunable technology is all about the user’s convenience and simplicity; it eliminates the need to remove, flip over, and adjust the chest piece to hear different frequency ranges.

What are the advantages of tunable diaphragms?

To go from bell to diaphragm mode on a stethoscope with a tunable diaphragm, the operator does not need to remove the chest piece from the patient. Single-sided chest pieces are also contoured to give a more comfortable grip for improved feel and control.

When listening to low-frequency sounds using a tunable diaphragm rather than a bell, the amplitude, or loudness, increases. This is due to the sound being transmitted through a diaphragm with a greater surface area than a smaller hole on a regular bell. Therefore, the sound pressure rises as the patient’s contact area expands.

The three key advantages of a tunable diaphragm are:

  • Save time by not having to set stethoscopes to hear all sound frequencies.
  • Improve diagnostics by isolating low and high frequencies. A tunable diaphragm allows for rigorous comparisons that yield sound judgments.
  • Improve convenience by eliminating the need to worry about putting the diaphragm at the same position where an abnormality was picked up. The only thing to do to hear another frequency is to put pressure on it.

What stethoscopes offer tunable diaphragms?

As a 3M patented invention, almost all 3M Littmann stethoscopes include an adjustable diaphragm. Electronic, pediatric, and baby stethoscopes are the exceptions. 

Their adjustable technology eliminates the need to remove, flip over, and reposition the chest piece to hear different sounds.

The tunable diaphragm is available for 3M™ Littmann® Master Cardiology™, Cardiology S.T.C., Cardiology III, Cardiology II S.E., Master Classic II, Classic II S.E., Select and Lightweight II S.E. stethoscopes.

To wrap up

A tunable diaphragm allows removing the need to switch between the bell and the diaphragm to hear low and high frequencies, respectively. 

With a tunable diaphragm, applying light pressure on the chest piece will isolate low-frequency sounds, while a firmer pressure will detect high frequencies. 

By eliminating the need to reposition the stethoscope, 3M tunable diaphragm technology changed the way stethoscopes can be used.

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