Noise-immune stethoscope helps medics hear vital signs in loud environments
...s within the range of human hearing, from about 20 hertz to 20,000 hertz. Most audible sound, including tha... of the heart and lungs, takes place at around 100 hertz to 200 hertz. The ultrasound models transmit a sound signal at 2.3 megahertz into the patient's body......ched ringing sound ranging between 4,000 and 8,000 hertz in frequency. At first, Zeng thought of treating...scribed as a "calming, pleasant tone" of 40 to 100 hertz of frequency -- which, when applied to the patient through a regular MP3 player, suppressed the high...