Sapira J D
St. Louis University, Missouri, USA.
Chest. 1995 Sep;108(3):865-7. doi: 10.1378/chest.108.3.865.
Egophony is a change in timbre (Ee to A) but not pitch or volume. It is due to a decrease in the amplitude and an increase in the frequency [corrected] of the second formant, produced by solid (including compressed lung) interposed between the resonator and the stethoscope head. This explains certain difficulties in learning this valuable but currently neglected sign as well as in understanding certain physiologic false-positive occurrences.
羊鸣音是音色的改变（“Ee”变为“A”），但音高和音量不变。它是由于在共鸣器和听诊探头之间存在实性物质（包括肺实变），导致第二共振峰的振幅减小而频率增加[校正后]。这就解释了在学习这个有价值但目前被忽视的体征时存在的某些困难，以及理解某些生理性假阳性出现的原因。
