Aumann Herbert M, Emanetoglu Nuri W
Department of Electrical and Computer Engineering, University of Maine, Orono, ME 04420, USA.
Healthc Technol Lett. 2019 Jul 31;6(5):143-146. doi: 10.1049/htl.2019.0011. eCollection 2019 Oct.
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.
通过在不失真的情况下，将低于50赫兹的心声、胸音和肠音转换到200赫兹这个人类耳朵易于察觉的频率范围，可改善声学听诊器的性能。这种频率转换对听力受损的医生将大有裨益，还会在嘈杂环境中提高听诊器的性能。该技术基于单边带抑制载波调制。全数字实现方式避免了通常与模拟频率转换器相关的稳定性和偏置问题。通过用时间延迟近似希尔伯特变换器，实现了实时音频处理。数字频率转换器的性能通过一个16位44.1千样本每秒的音频编解码器和一个32位72兆赫兹的微控制器进行了验证。
