2004 OPEN FORUM Abstracts
A COMPARISON OF EIGHT CARDIOLOGY STETHOSCOPES.
Jonathan B. Waugh, PhD; Dale W.
Callahan, PhD; Wesley M. Granger, PhD; George A. Mathew, MS.
University of Alabama at Birmingham, Birmingham, AL.
BACKGROUND: There are
many brands of stethoscopes currently marketed. Little data exists
to guide clinicians on the differences between models that often vary
greatly in price. We tested eight high-quality stethoscopes to
determine if there was a difference in average frequency response.
METHODS: Eight
different models (Littmann Master Cardiology, Advanced Diagnostics Corp. Adscope
601, Heine Optotechnik Gamma20,
Allen Medical Instruments Gemini 23”, Welch Allyn Harvey DLX
and Elite, Philips Rappaport-Sprague, Doctor’s Research Group
Puretone Cardiology) of adult “cardiology” stethoscopes
(8 had diaphragm chest pieces, only 7 had bell chest pieces) were
measured using a pure tone (sine wave) sweep input from 50-3000
Hertz. Four copies of each model were tested and the data averaged
for comparison by ANOVA. The average relative change in decibels
(dB) (difference of stethoscope output signal from reference input
signal) for each model over the measured frequency range was
compared.
RESULTS: The ANOVA indicated a difference among models
for the bell and diaphragm chest pieces (p<0.001). The stethoscope
bell chest piece with the least negative average dB value (closer to
zero dB the better) was the Welch Allyn DLX (post hoc analysis by
Tukey-Kramer Test showed this model was significantly different
[p<0.05] from all other models). The dB means for the bell
measurements ranged from –7.80 to –14.20. The diaphragm
chest piece with the least negative value was the Philips
Rappaport-Sprague (post hoc analysis showed this model was
significantly different from all other models except the Allen
Medical Instruments Gemini 23”). The dB means for the
diaphragm measurements ranged from –11.10 to –13.73.
DISCUSSION: The
results show that the best bell and diaphragm values did not occur with the
same model of stethoscope. There was a
greater range of values for the bell chest pieces than with the
diaphragms chest pieces.
CONCLUSION: Bench testing using
computerized signal processing methods shows statistical differences
between the models tested. These results need to be compared to
testing done with experienced human auscultators to see if these
statistical differences have clinical significance.