Volcanos, Rock Bands & Jets

An essay by James A Graves, Jr.

I recently saw an internet video that claims the loudest sound ever heard by humans was the eruption of the Krakatoa Volcano, located on an island in what is now Indonesia, in 1883.

In fact, the Krakatoa Volcano was the island, which was gone after the eruption.

The sound level of the eruption was supposedly 310dB. Which is a seriously loud boom. Sailors’ eardrums were reportedly ruptured 40 miles away, and a sound level of 180dB was reportedly measured 100 miles away, which would have supposedly still rupture eardrums. That’s possible, 180dB is also a really loud boom.

I found that report interesting. Although, it makes me wonder about the effects of the Mount Saint Helens eruption. Although minuscule compared to Krakatoa, many people were geographically much closer to Mount Saint Helens and I don’t recall any reports of eardrums being ruptured. I wonder, was no eardrums ruptured by the Mount Saint Helens eruption, or were eardrums ruptured and no one reported it?

Having been a Rock musician, as well as a technician in military and civilian aviation, I’m familiar with loud sound. I thought that Deep Purple held the Rock concert record as the loudest Rock band: “…recognized by The Guinness Book of World Records as the "globe's loudest band" when in a 1972 concert at the London Rainbow Theatre their sound reached 117 dB. Three of their audience members were rendered unconscious.”

But Deep Purple isn’t even close. Several other Rock groups are much louder, including Manowar, who reached 139dB during a sound check before a concert in 2008.

My reward for being a Rock musician, and working around military fighters and commercial jets, is tinnitus. But on a strange side note, my tinnitus isn’t really all that bad, relatively speaking, because it actually sounds like the cacophony generated by all of the cicadas, crickets and frogs competing to be the loudest critter on a summer night when I was growing up at Morrison Spring in the Choctawhatchee River swamp of Northwest Florida.

With no air conditioning in our tin-box house trailer, those countless numbers of swamp critters provided a nightly summer concert just outside my bedroom window. These days, when it’s very quiet, it just sounds like I’m back home at Morrison Spring.

Oddly enough, despite being second lead in a professional, kickass Southern Rock band, the loudest concert I’ve attended was ZZ Top in Tucson on their Recycler Tour in the 1990’s. After that concert my ears didn’t just ring, they actually ached, which was a new, and somewhat unpleasant, experience for me.

But the loudest sound I’ve ever heard, by far, was my first and last encounter with a jet running beyond Mach 1 at tree top level. It happened early one peaceful, quiet summer morning in the mid 1960’s at Morrison Spring. I was 15 or 16, busily doing my chores, which included repainting each and every one of our rental boats, every summer. What fun that was.

I glanced up from concentrating on my joyous painting chore just in time to see a totally silent, silver, delta wing shape flash directly over me, just above the treetops. Being an airplane nut, I’m certain it was either an F-102 Delta Dart, or an F-106 Delta Dagger, most likely one of the fighter-interceptors based at Eglin AFB in Niceville, FL, or Tyndall AFB in Panama City, FL, both bases about fifty miles distant.

The only other supersonic delta wing jet at that time was the B-58 Hustler, and not assigned to Eglin, which only had B-52’s. Besides, the silhouette wasn’t large enough to be the big, four engine B-58.

Many different aircraft, including jet fighters, often flew low over our area, so I was accustomed to seeing them, and hearing sonic booms, but never up close and personal. Since most of the cypress and sweetgum trees around Morrison Spring were around 50 to 70 feet tall, I estimate the jet was about 100 to 150 feet above me. The silver, delta winged image literally filled most of my field of vision, but just for the blink of an eye.

Even before my mind could generate the complete thought of, hey, that was a jet, but where’s the sound?! the shockwave hit. It was literally, hey, that was a…WHAM!!

The sound was incredible, and almost indescribable. Not the characteristic “double boom” of the sonic booms that I heard constantly in those days, and not the ear shattering boom of the cherry bombs & M-80s that I used for my adolescent demolition projects, nor the sound of a shotgun, rifle, or pistol that I shot regularly. Those pale in comparison.

This “wham” was mechanical in nature, a metallic blast from the full audio spectrum, mixed into a vicious, crushing volume level that I not only heard, but felt. It left me dazed, my ears ringing and my lungs almost breathless.

And there was no time to react. Afterward, I stood there in blank, mindless shock, my heart pounding, with the familiar quiet of the Morrison Spring swamp all around me. Then some unknown number of seconds later I regained conscious thought and shouted, “Holy shit!!”

Unfortunately, I wasn’t facing the water so I don’t know if the supersonic pressure wave produced ripples or not. I’d bet that it did because the pressure wave was probably what affected me the most; “Feeling sound” was something fairly alien to me. I had felt the air moving while standing in front of my bass player’s amp, but I never imagined sound could literally pound me into the ground.

I was reminded of that supersonic shockwave in later years while standing beside (instead of behind, where I should have been) a .357 magnum pistol being fired, and again when my son fired his .357 magnum rifle. The rifle seemed even louder, but I think that was because we were on a lake, shooting at a gator, however, those booms were nothing compared to that jet.

I came to the conclusion that the rifle shot on the lake seemed louder because water reflects sound. As a kid, my buddies and I would throw cherry bombs and try to time it so they would detonate just above the surface of the water at the spring. Not only was the sound louder, but it echoed down the spring run. We thought that was too cool.

Dangerous fireworks and adolescent boys – not a good combination.

These days, fifty years hence, I hear, and then look up to see air carriers, just out of Phoenix Sky Harbor, already at cruising altitude, flying over Payson, heading northward, and I wonder how many people realize just how damn loud those jet aircraft really are. And modern air carrier aircraft are almost quiet when compared to a military fighter jet.

Although ear protection is the logical solution for working around jet aircraft, the USAF Avionics Maintenance Squadron that I worked for never issued earplugs. I’m not sure why, maybe it was due to concerns about foreign object damage (FOD) to jet engines.

No hats or other loose personal items were allowed on the ramp (flight line), except for a little neon bulb soldered to a copper gator clip that the radar techs clipped onto a pocket flap of their fatigue shirt while working on the RF-4’s terrain following radar. The neon bulb would glow when hit with a high level of microwave radiation, like that emitted from the radar antenna, which can be fatal, making the neon bulb sort of a “you’re screwed” indicator.

I joked with my trainees and co-workers that the radar techs only used the gator clips for roach clips, otherwise they were essentially useless. Those neon bulbs only glowed when being bombarded with lethal microwave radiation, which meant the wearer was also being bombarded with lethal microwave radiation, so, if a “you’re screwed” indicator illuminated, it was already too late to do anything about it.

For ear protection we had audio headsets (with the microphone shell that covers your mouth) to plug into the aircraft intercom system. The nosepickers & tire kickers (crew chiefs) used those, too. Everyone else had common headset ear protectors, but they weren’t widely used.

I remember a staff sergeant from one of the maintenance shops, using no ear protection and bitching at me because I kept my headsets on as he was talking to me beneath the tail of an F-4 with a dash 60 power cart running a few feet away and two F-4s with engines running nearby preparing to taxi. I’ll bet he’s nearly deaf today.

And me? Oh, I can hear just fine – as long as the cicadas, crickets and frogs keep it down to a low roar.

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