Design, construction, and evaluation of a bioacoustic transducer testing (BATT) system for respiratory sounds.
Many different transducers are employed for recording respiratory sounds including accelerometers and microphones in couplers. However, there is no standard lung sound transducer or any device to compare transducers so that measurements from different laboratories can be determined to be of physiologic origin rather than technical artifacts of the transducers. To address this problem, we designed and constructed a prototype of a device that can be used to compare accelerometers, microphones enclosed in couplers, and stethoscopes. The prototype device consists of a rigid chamber containing a loudspeaker that opens to an antechamber covered by a viscoelastic material with mechanical properties similar to human skin and subcutaneous tissue. When driven by a white noise source, we found the sound output at the surface to be useful to comparatively evaluate sensors between 100 and 1200 Hz where lung sounds have most of their spectral energy. We compared the viscoelastic layer to similar thicknesses of fresh meat and fat and found them to produce similar acoustic spectra. This device allows air-coupled transducers, accelerometers, and stethoscopes used in respiratory sounds measurements to be compared under physical conditions similar to their intended use.
Kraman
Steve S
SS
Department of Internal Medicine, the University of Kentucky, Lexington 40536, USA. sskram01@uky.edu
Pressler
Gary A
GA
Pasterkamp
Hans
H
Wodicka
George R
GR
D000162:Acoustics / Q000295:instrumentation*; D001314:Auscultation / Q000295:instrumentation* / Q000379:methods; D040761:Biomimetic Materials; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008168:Lung / Q000502:physiology*; D015203:Reproducibility of Results; D012135:Respiratory Sounds / Q000502:physiology*; D012680:Sensitivity and Specificity; D014159:Transducers