A Robust Multichannel Lung Sound Recording Device

Abstract

This paper presents a robust multichannel lung sound recording device (LSRD) for automatic lung sound classification. Compared to common approaches, we improved the usability and the robustness against body sounds and ambient noise. We developed a novel lung sound transducer (LST) and an appropriate attachment method realized as a foam pad. For analogue prefiltering, preamplification, and digitization of the lung sound signal, we use a composition of low-cost standard audio recording equipment. Furthermore, we developed a suitable recording software. In our experiments, we show the robustness of our LSRD against ambient noise, and we demonstrate the achieved signal quality. The LST's microphone features a signal-to-noise ratio of SNR = 80 dB. Therefore, we obtain a bandwidth of up to a frequency of f ≈ 2500 Hz for vesicular lung sound recordings. Compared to the attachment of the LST with self-adhesive tape, the foam pad achieves an attenuation of ambient noise of up to 50 dB in the relevant frequency range. The result of this work is a multichannel recording device, which enables a fast gathering of valuable lung sounds in noisy clinical environments without impeding the daily routines.

Lung Sound Classification Using Co-tuning and Stochastic Normalization

“…The multi-channel lung sound database [9], [19], [28] has been recorded in a clinical trial. It contains lung sounds of 16 healthy subjects and 7 patients diagnosed with idiopathic pulmonary fibrosis (IPF).…”

“…The systems have been evaluated on non-public datasets such as R.A.L.E. [8] or multi channel lung sound data [9] (ours) and public datasets i.e. the ICBHI 2017 dataset [5] or the Abdullah University Hospital 2020 dataset [10].…”

A Wearable Stethoscope for Long-Term Ambulatory Respiratory Health Monitoring

“…The central element of the sensor module, the acoustic transducer, can either be realized by using an air microphone [ 6 , 7 , 8 ] or a contact microphone [ 9 , 10 , 11 ]. Air microphones (electret condenser microphones and capacitive or piezoelectric MEMS microphones) are commonly inserted into the stethoscope heads [ 8 ] in order to benefit from an optimized mechanical design to guide the pressure waves. The work [ 12 ] provides a detailed analysis on the impact of different mechanical designs.…”

“…Positioning of the transducers on the posterior chest defines which pulmonary diseases are of interest for diagnosis. The works [ 7 , 8 ] employ slightly different patterns for placing the transducers, yet all these systems incorporate more transducers close to the diaphragm than close to the neck as a natural result of the respiratory system geometry. Stabilization of the sensors is critical as it reduces the low-frequency noise stemming from movement artefacts.…”

“…In order to stabilize the transducers on the skin, using adhesive tapes has been preferred due to its simplicity [ 13 ]. However, placing the transducers into a foam pad [ 8 ], [ 14 ] is shown to benefit from both better stabilization and, with proper material selection, ambient noise reduction. The work [ 8 ] reports attenuation superiority of a foam pad compared to adhesive tape approach, which can reach up to 50 dB difference.…”