In the following plot of respiration during meditation, we see a regular repetition of inhalations and exhalations with a wave-like quality.
My breath recorded on the 7th day of a meditation retreat.
Selecting a range of cycles, we can average the values centered around the peaks to extract a waveform that represents the entire range. Averaging over 12 cycles, we get the following:
Average waveform of the breath for subject S1 (myself) at the end of a 7-day meditation retreat
An interesting aspect of this waveform is that the exhalations are almost twice as long as the inhalations. Here, one complete cycle is 19 seconds long which corresponds to 3.2 breaths/minute. Compare this with the waveform for reading:
Average waveform of the breath for subject S1 quietly reading