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Experimental validation of the tuneable diaphragm effect in modern acoustic stethoscopes
  1. Karolina M Nowak1,2,
  2. Lukasz J Nowak2
  1. 1 Department of Endocrinology, Centre of Postgraduate Medical Education, Warsaw, Poland
  2. 2 Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
  1. Correspondence to Karolina M Nowak, Department of Endocrinology, Centre of Postgraduate Medical Education, Ceglowska 80, Warsaw 01-809, Poland, knowak{at}


Purpose The force with which the diaphragm chestpiece of a stethoscope is pressed against the body of a patient during an auscultation examination introduces the initial stress and deformation to the diaphragm and the underlying tissues, thus altering the acoustic parameters of the sound transmission path. If the examination is performed by an experienced physician, he will intuitively adjust the amount of the force in order to achieve the optimal sound quality. However, in case of becoming increasingly popular auto-diagnosis and telemedicine auscultation devices with no such feedback mechanisms, the question arises regarding the influence of the possible force mismatch on the parameters of the recorded signal.

Design The present study describes the results of the experimental investigations on the relation between pressure applied to the chestpiece of a stethoscope and parameters of the transmitted bioacoustic signals. The experiments were carried out using various stethoscopes connected to a force measurement system, which allowed to maintain fixed pressure during auscultation examinations. The signals were recorded during examinations of different volunteers, at various auscultation sites.

Results The obtained results reveal strong individual and auscultation-site variability.

Conclusions It is concluded that the underlying tissue deformation is the primary factor that alters the parameters of the recorded signals.

  • stethoscope
  • auscultation
  • tunable diaphragm
  • chestpiece

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  • This paper has previously been published as conference Proceedings of the 22nd International Congress on Acoustics. Buenos Aires, 5-9 Sep 2016. Biomedical Acoustics: Paper ICA2016-405.

  • Contributors KMN planned and conducted the study and drafted and revised the paper. KMN is the guarantor. LJN conducted the study, analysed the data and revised the paper.

  • Funding The Polish National Centre for Research and Development (NCBiR), grant no. LIDER/034/037/L-5/13/NCBR/2014.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval The Ethics Committee of the Centre of Postgraduate Medical Education.

  • Provenance and peer review Not commissioned; internally peer reviewed.