"I can't hear anything!"
The bane of EMS existence at some challenging times, auscultating lung, heart and other body sounds can prove quite difficult dependant on a number of factors, whether related to patient, equipment or other ambient noise.
Sound reaching the practitioner's ears from a patient's body is often quiet enough to warrant using a stethoscope; we’re talking quieter lung sounds, not speech, rumbling belly bowel sounds, the "hear it a mile away APO" or very loud stridor, for example.
A stethoscope has a resonator which is placed close enough to the sound source (eg. on the patient's chest) and creates acoustic pressure waves in response to sound vibration, which travel up hollow tubes to the listener's ears. An advanced stethoscope has inner lumen which further amplifies sound. The further advanced stethoscope has dual lumen which creates two sound paths within one inner tube, instead of dual-tubed stethoscopes which generate a rubbing noise causing sound interference.
Having a good stethoscope is only part of the challenge! Of course other factors influence the ability to auscultate.
Auscultating the right location is important to ensure sound clarity; this is why in school we are taught anatomical locations - to best hear sound in different areas. Refer to your instructional resource for where to auscultate, and perhaps consider keeping a flash card or other handy resource if it is difficult to recall precise locations.
External factors including physical barriers (eg. patient clothing, medical factors such as emphysema and adipose tissue) reduce the ability of sound to conduct. The presence of ambient noise (including other noise occurring in the patient’s body) may also disturb the clarity of and overshadow the sound you are trying to auscultate.