The Invention and Evolution of the Stethoscope
It's two hundred years since French physician René Laennec, in a flash of inspiration, invented and named the stethoscope. He started with a roll of paper and quickly progressed to a hollow wooden tube about 30 cms long. Laennec specialized in treating the scourge of nineteenth-century cities - tuberculosis - and found his new idea to be invaluable.
While not all were convinced that his invention was of much value, medical professionals from across Europe climbed onto their horse or into a carriage and traveled to Paris to learn about his ideas. Over the next thirty years, Laennec’s innovation, the monoaural (having a single earpiece) tubular stethoscope became a feature of many a doctor’s bag.
The Stethoscope Continues to Evolve
While it was a huge step forward in diagnostic technique, the Laennec stethoscope wasn’t very convenient to use. It required the doctor to lean over their patient, which wasn’t always easy, particularly for physicians with their own mobility issues.
In the late 1830s, Doctor John Burne began using a flexible stethoscope in his work at Westminster Hospital and in private practice. While it offered no acoustic benefit over the rigid design, it was easier to use in certain circumstances. Modest young women were more comfortable with the flexible model, as it allowed them to apply the chest piece themselves.
The early flexible stethoscope was still monoaural. In 1840, British doctor Golding Bird published the first design for this form of stethoscope with a flexible tube. Bird suffered from severe rheumatism and preferred to work sitting down, hence his preference.
Two Ears are Better than One
It didn’t take long for medical innovators to explore the idea of having two earpieces. Several developed their own models but they remained a novelty until the early 1850s when George Cammann of New York designed a device that entered manufacture. At a quick glance, the Cammann stethoscope looks similar to instruments in use today, although with a funnel instead of a bell as the chest piece.
One curious variant was the double stethoscope, which is effectively two monoaural models put together into a binaural configuration.
The Modern Stethoscope Arrives
In the 1940s, Rappaport and Sprague developed a reversible bell. One side was designed for the respiratory system and the other for the cardiovascular system. Innovation continued as Dr. David Littmann, a professor at Harvard Medical School, pursued his ambition to create a lighter instrument with better acoustic performance. He built a workshop in his basement where he developed around thirty different designs until he created one that met his exacting standards.
In the days that followed, Littmann made and gave away his new stethoscopes to friends and colleagues. It became clear there was a market for his highly portable design and he began selling a dozen or so each week. Within a few years, the Littmann stethoscope became the gold standard for the modern medical instrument.
The Stethoscope Today and Tomorrow
Two hundred years after René Laennec created the first stethoscope with a roll of paper, the instrument that has become the symbol of medical professionalism continues to be improved. Some of the latest versions include digital amplification and connectivity, making it easier for the user to hear even in difficult situations, and to record and share sound. Newer models of the stethoscope are designed to eliminate potentially distracting sounds made by the device itself, such as any movement between components in the chest piece or in the connecting tubes. Check out the newest model from Littmann, the Littmann CORE Digital, Littmann's most advanced model yet.
Newer technologies, such as ultrasound and echocardiograms, are touted by some as the successors to the traditional stethoscopic examination. However, today’s medical students are still trained in auscultation - the ability to make a diagnosis based on sounds made by the body, as heard through a stethoscope. This simple device has served the profession and its patients well for two hundred years, and it looks set to continue working hard for a good while to come.