In the extend range mode (20 – 1000 Hz), the ambient/background noise is higher than that in other modes such as bell mode. There are three reasons:
- At extend range, the sounds picked by the Stemoscope have a wider frequency range, so when the Stemoscope picks up more signals, it also picks up more noise.
- The noise at the higher frequency range (200 – 1000 Hz) is more audible than that at the lower frequency range (20 – 200 Hz) because our ears are more sensitive to the high frequency sounds.
- When the audio signals are amplified, the noise too. If you lower the volume level to the level close to that of a traditional stethoscope, the ambient noise is less audible. Actually the ambient noise level of Stemoscope is similar to that of a traditional stethoscope. However, the digital amplification of the Stemoscope amplifies the noise and make you feel the noise level is higher.