Normal breathing is said to vary between 12 and 20 cycles per minute, that is, 3 to 5 seconds per cycle. But breathing may be slowed down during relaxation or sleep to cycles lasting 6 to 8 seconds. Part of the sense of well-being we feel at the seashore undoubtedly has to do with the fact that the relaxed breathing pattern shows surprising correspondence with the rhythms of the breakers, which, while never regular, often produce an average cycle of 8 seconds.

Schafer, Murray R, The Soundscape- Our Sonic E…, loc. 751