一种可用于强噪声环境的有源听诊器

介绍了一种不仅可作为传统型无源听诊器使用,更可用于强噪声环境的抗噪声有源听诊器。该听诊器通过切换开关在传统的听诊器和有源听诊器之间切换。在有源模式时收发合置的超声探头向人体内发射2.3 MHz的超声波,并被人体组织反射,人体组织的运动,比如心脏的搏动、肺部的舒张、血管的脉动等引起反射超声的多普勒效应,这些频率变化经计算转换为可听声,则可用于后续的诊断等。经实验室验证,该听诊器在120 dB声压级的强噪声环境下在有源模式时仍可清晰地诊断心音,而传统听诊器可适用的最高环境噪声不超过80~85 dB声压级,电子听诊器则为90~95 dB声压级。

A noise-free active stethoscope for use in noisy environments

A noise-free active stethoscope was introduced, which can be used not only as conventional passive stethoscope, but also as ultrasound-based active stethoscope for use in noisy environments. It allows a physician to switch on and off between passive and active modes during auscultation of a patient. In active mode, a high-frequency (2.3 MHz) sound signal is generated, transmitted from the stethoscope head into the patient's body, and reflections from moving body tissue are picked up by a receiver also located in the stethoscope's head. Since these reflections have a slightly different frequency than the transmitted signal caused by the Doppler effect, a difference-frequency can easily be computed and made into an audible sound. The experimental results show that for conventional stethoscope, the maximum noise level that still allows successful auscultation is between 80 dB and 85 dB Sound Pressure Level (SPL); for modern electronic stethoscopes the maximum noise level is to about 90N95 dB; but even in a noise level of 120 dB SPL, the ultrasound stethoscope's output remains noise-immune.