In 1953 Captain Jacques Yves Cousteau, just a wisp of a former French naval lieutenant, and underwater enthusiast who was part of a group which had recently quasi-developed an underwater breathing device, penned the book “The Silent World”. Scuba diving had been brought to the masses, and in what was the beginning of a family tradition of blatant perpetual self-promotion, the good Captain brought the newly found underwater wonders to spellbound readers, and then to viewers in 1956 with his film bearing the same title, “The Silent World”.
Jacques Yves Cousteau has become legendary as the father of Scuba Diving. Millions of the boomer generation grew up discovering the wonders of scuba diving through his films presented on the television specials; “The Undersea World of Jacques Cousteau”. He was a naval officer, explorer, conservationist, filmmaker - “The Silent World”, innovator, scientist, photographer, author of “The Silent World”, and researcher who studied the sea and all forms of life therein. He co-developed the Aqua-lung, pioneered marine conservation, and was a member of the Académie française. Did we mention his book/film, “The Silent World”?
Far be it from me who wasn’t even born when Messrs. Cousteau and Dumas developed the Aqua Lung, to disparage the knowledge and publications of such a learned and respected individual. But, where is this “Silent World” we are hearing about?
There is nothing really silent about Scuba Diving, or being underwater. Cousteau’s film “The Silent World “opens with the pop of an underwater magnesium flare going off, and the descent of a group of divers into the brilliant sun lit Mediterranean Sea accompanied by the roar of bubbles rising to the surface from five divers and torches all in pre Dolby monaural audio.
“Sound”, as we are used to it is actually our brain’s interpretation of signals sent to it by the eardrum as it reacts to pressure waves in the air. These pressure waves radiate from their sources at about 750 miles an hour, and allow us to be aware of things like train wrecks, should they occur behind our backs. Over distance these waves expand and dissipate and eventually become inaudible (give yourself about three miles for the standard Spinal Tap concert).
However, underwater things are a bit different. Water is 800 times denser than air, allowing the pressure waves (sound) to travel much faster and farther. Sound underwater travels at about 3500 miles per hour, and for distance it is claimed that whales can hear each other and communicate over thousands of miles of ocean, although I am not at all sure how that is ascertained. Underwater our perception of these pressure waves no longer comes from the eardrum, because it is compromised by the water against it, which keeps it from vibrating. Instead our brain receives “sound” pressure wave signals via the mastoid bone, that hard bit just in back of your ear. It is reported that humans can hear higher pitches of sound underwater better than in air.
Sound underwater is five times faster, travels hundreds of times further than we are used to, and is hard wired to a bone in our head. When you first experience Scuba Diving, and being underwater you will quickly learn that this is hardly “The Silent World”. As divers we generate a bit of noise ourselves. With every breath there is the hiss of air through our regulators and the roar of bubbles rising past your head as you exhale. This very necessary noise is enough to warn and scare some of the reef fish away from you.
The denizens of the seas contribute a lot of noise. We are all familiar with the sounds made by whales, orcas, seals, and dolphins with their songs and yakking, via videos if not in person. We watch Humpback whales breaching crashing into the ocean like arctic icebergs and Hawaiian lava, and these sound waves can travel countless miles and miles.
Smaller fish along the reef contribute to the local underwater noise. Parrot fishes break off coral with their beak like mouths making a background of clicking sounds. Grunts, snappers, and toad fish make grunting, snapping, and toad-like sounds along with the constant popping sounds of shrimp. It is said that a healthy reef sounds like popcorn, or bacon sizzling from the sounds of shrimp and other reef cleaners.
Last, and never least, there is man and his sonic contributions to this auditory pie. Who knows what level of noise comes from the combined efforts of construction, mining, drilling, shipping, and commerce? Add to this the military and their penchant for quiet and demure projects ballistic and otherwise, it can be noted that we contribute our fair share of underwater sound.
Regardless of this rant, do not let the fear of sonic overload keep you from entering the water. Scuba diving is an incredibly relaxing and peaceful activity, partly because there are no conversations, but the sounds are part of the fun. As examples; I have spent a grand bit of time looking for Toadfish that are so easy to hear yet hard to find, and we still marvel at the sounds of earthquake aftershocks underwater here seven years ago. It is all part of the great underwater adventure!
But I wonder, Monsieur Cousteau, where were you diving?