Acoustic performance of three stethoscope chest pieces

This study compared the spectral response of three different stethoscope chest pieces (Tycos Harvey, Littmann Classic II, Tollot Dual Head) to both pink noise and normal human breath sounds recorded from the chest wall of 12 subjects breathing at an average peak inspiratory flow rate of 1.5 L/s. The sound data was subjected to fast Fourier transform (FFT) algorithm analysis. The pink noise data showed frequency accentuation between 100 and 1250 Hz occurred with all the chest pieces but was most prominent with the Littmann and least with the Tycos Harvey chest piece. Inspiratory breath sound analysis showed that the peak intensity (PI) recorded using the Littmann chest piece was highest and the Tollot lowest, whilst the frequency at maximum power (F_max) recorded using the Tycos Harvey chest piece was highest and the Tollot lowest. There was no difference in the frequency (F₅₀) and band width at half power during inspiration between the three chest pieces. All parameters measured during inspiration were significantly different from that measured during expiration, except for F₅₀. This study demonstrates that the acoustic performance of stethoscope chest pieces is different, with the Littmann displaying the highest gain in intensity at adventitial sound frequencies and appears most suitable for lung sound auscultation in the clinical setting. However, the superior F_max of the Tycos Harvey chest piece suggests superior diaphragmatic auscultation of high frequency sounds such as wheezes