Rappaport and Sprague designed a new stethoscope in the 1940s, which became the standard by which other stethoscopes are measured, consisting of two sides, one of which is used for the respiratory system, the other for the cardiovascular system.
Rappaport e Sprague deseñaron un novo estetoscopio na década de 1940, que se converteu no estándar, con dous tubos, un para o sistema respiratoiro e outro para o cardiovascular.