The PneumoSim is a most unusual teaching instrument. It contains both simulated and real breath sounds. The underlying theory is that the student can learn the sounds more easily using simulated sounds, then listen to the same sound under study from a real patient.

When using the simulated sounds, the instructor (or student) can control many of the aspects of how the sounds are presented. They can be played just as they are or they can be altered. Because of the great variety of sounds produced by patients, it is difficult to produce a single sound of a particular condition that fits everyone.

Therefore, the simulator allows the user to make a number of changes to the existing sounds. These changes can be saved, if desired, and recalled at will. The changes that can be made to any sound are:

• respiration rate (from 10 to 100 breaths per minute),
• the display of the sound can be changed from one to seven cycles,
• the I:E ratio can be changed,
• adventitious sounds can be added to any normal sound,
• the position of the adventitious sounds can be changed (first 1/3, second 1/3, third 1/3, any combination of the foregoing, or full. The sounds can be changed from inspiration to expiration or vice versa,
• The length of the expiration can be controlled,
• The pause at the end expiration can be altered or eliminated,
• Another pause at the end of inspiration may be added,
• The display can be shown as an upward ramp for inspiration and downward for expiration or changed to a flat display. The breath sounds are superimposed on the display so the user will know exactly where in the cycle they appear.

The library of sounds covers all normal and practically all abnormal sounds. Egophony is also included as spoken voice (1,2,3 - normal and abnormal), whispered voice (1,2,3 - normal and abnormal) and spoken voice (99 - normal and abnormal).

The PneumoSim also contains a built-in patient auscultation unit that allows the instructor or student to listen to their own or patient sounds from their institution. These sounds can be digitally recorded, if desired, and played back at will. After recording, they can be filtered to reduce background noise.

The PneumoSim can be added to the CardioSim Digital Heart Sound Simulator. In this mode, the total system will present breath sounds, heart sounds, bowel sounds, arrhythmia recognition, echocardiograms, chest X-rays, and 12 lead electrocardiograms.