Stethoscope with digital frequency translation for improved audibility

[摘要] The performance of an acoustic stethoscope is improved by translating, without loss of fidelity, heart sounds, chest sounds, and intestinal sounds below 50 Hz into a frequency range of 200 Hz, which is easily detectable by the human ear. Such a frequency translation will be of significant benefit to hearing impaired physicians and it will improve the stethoscope performance in a noisy environment. The technique is based on a single sideband suppressed carrier modulation. Stability and bias problems commonly associated with an analog frequency translator are avoided by an all-digital implementation. Real-time audio processing is made possible by approximating a Hilbert transformer with a time delay. The performance of the digital frequency translator was verified with a 16-bit 44.1 Ks/s audio coder/decoder and a 32-bit 72 MHz microcontroller.

[学科分类] 肠胃与肝脏病学

[关键词] Hilbert transforms;audio coding;analogue-digital conversion;bioacoustics;cardiology;biomedical equipment;medical signal processing;microcontrollers;modulation;intestinal sounds;analog frequency translator;digital frequency translation;acoustic stethoscope;heart sounds;chest sounds;Hilbert transformer;single sideband suppressed carrier modulation;hearing impaired physicians;microcontroller;time delay;audio coder-decoder;frequency 200.0 Hz;frequency 72.0 MHz