Volume Settings and Psychoacoustics

It is suggested that volume levels be varied when listening to each patient. Body sound characteristics and detail change as the signal is amplified to different volume levels. Sounds also vary with Probe position, diaphragm pressure, age and obesity of patients.

The human auditory system “masks” quieter sounds with louder sounds. This is often a problem when using a conventional stethoscope, where louder heart sounds mask quieter sounds such as murmurs, and there is no way to control volume. By listening to the same sounds at different volume levels, auditory masking can be exploited, rather than being a limitation. At low volumes, masking will help to hear only certain louder sounds and quieter sounds will be masked. At higher volume settings, the ds32a will allow the auditory response to overcome masking effects to hear low-amplitude murmurs “through” the louder sounds. Volume levels from 5-8 are usually optimal.

Some users might prefer to use the pre-set Acoustic mode for most listening, using the Amplify mode when further signal detail is required.

It should also be noted that diaphragm pressure changes the sensitivity of the EmD sensor. Increasing pressure will increase sensitivity, and therefore volume. See page 19 for further details.

Warning - Protect your Hearing: Permanent hearing loss or Tinnitus can result from exposure to high sound pressure levels. Threshold shift (adaptation to high volume) makes loud sounds seem normal. Use caution when listening at high Volume, and limit exposure to loud sounds.