When conducting an experiment that involves the human respiratory system, one of the most important pieces of data to collect is the tidal volume of the subject. Tidal volume is defined as the amount of air exchange in normal breathing. In other words, tidal volume is the differential between air inhaled and exhaled by a particular person. Typically, when calculating tidal volume and other respiratory scientific figures, researchers will use a respirometer, which the subject blows into. The respirometer will then produce wavelike graph results, which can then be measured.
Select a particular breath you want to measure. Each breath is displayed on the respirometer graph as a wave with a peak and valley.
Identify the numerical values of the peak and valley of the breath selected by matching them with the number (in ml) on the left of the chart. Record the two numbers.
Subtract the valley number from the peak number obtained for that specific breath. The result will be the tidal volume, in ml, of that particular breath.
Repeat this process to calculate the tidal volume for as many breaths as desired.