What would happen if someone flew a brand new Cessna Skylane/Caravan or a Robinson R22 without using earplugs or headphones? Would they get hearing damage or it would be just a little bit loud where communication with co-pilot need constant yelling? How serious ear damage is?
This study on cabin noise with experiments in a Cessna 172s and a Piper PA-44 got the following results (noise comparisons are mine):
- Without headset: 101.3 dBA = rock concert (not front row though)
- With headset: ~88 dBA* = vacuum cleaner (old bag-style ones, not Dyson...)
- Without headset: 86.26 dBA = heavy traffic (by the side of the road)
- With headset: ~73 dBA* = cloth dryer
Those value are not terrible per-se but on the long term ear damage is very likely.
*The study found that a headset reduces the loudness by 13 dBA in average. The reduction should be even higher with a noise cancelling headset.
To supplement Quentin's answer, the effects are accumulative and depend on the level of exposure.
Most of the noise in a cockpit is low frequency sound of 75 to 100 hz with a 4 cyl engine/2 blade prop or 100 to 150 hz with a 6 cyl and 3 blade prop. Then there is the usual wide spectrum machinery noise and the white noise from the airflow.
Long term exposure above about 84 dB will create hearing loss. Short term exposure above 105-110 dB will create hearing loss of some amount after one shortish exposure, maybe only a couple percent, but repeat it a number of times and you start to notice. If something makes your ears ring temporarily after, that's bad.
84 dB is about the level of driving a convertible with the top down at 70 mph (that came from research done in Britain on hearing loss from driving). A rock concert is above 100 dB. Once reason concert sound levels are so high (besides the fact they are catering to foolish young people) is the sound guys themselves are half deaf (One of my children is a performer and musicians and sound techs in the last decade or so have finally started to take steps to protect their hearing).
Airplane noise levels vary a lot. The quietest aircraft are wooden ones, and composite ones, and ones with thick windshields and windows.
I'm in my early 60s with pretty good hearing below about 12 kHz, which is actually really good for my age, but with tinnitus that is a steady 10-12 kHz tone that never goes away, that I've had for many years but slowly gets louder as I age. I've worn earplugs and/or headsets since I learned to fly in 1975 and I'm sure I'd be pretty much nearly deaf if I hadn't. Tinnitus can come from things other than loud noise, so it may just be bad luck.
Today, I wear an passive noise reduction headset, with ANR added, AND earplugs, having become obsessive about avoiding more hearing loss and making my tinnitus worse.
Anyway, a one-time flight with no hearing protection for an hour, in anything that doesn't leave your ears ringing after, probably won't have any more effect than all the other loud noises you will be exposed to over the years. It's repeated exposure.
So if you have no choice in the matter, I wouldn't be concerned about a one-time ride, but don't make a habit of it. But you really should take earplugs with you, and if you are offered a headset and/or earplugs, you are crazy to turn them down.
I measured levels in the cockpit area of a twin Cessna where the propellers were inline with the pilot to the left and right and levels were 110dBA where I would be sitting. Levels were 100 in the back in the cabin. Without headsets, it would be impossible to communicate with crew/passengers and I'm sure hearing loss would result.
If you're crew, you probably want to be wearing a headset for communication purposes.
For passengers, these airplanes were flown for many decades before headsets became common (even for crew, using the handheld mic and overhead speaker) and long-time instructors had slight hearing loss, but for the random person taking a scenic flight to look at leaves or property on an occasional basis, I think you'd be fine without hearing protection.
Comm's would be very difficult, and hearing would be damaged eventually (ringing in ears, like being at loud rock concert). 180 horsepower engine in R22 makes a lot of noise, then add in noise from props and blades, and radio over an overhead speaker is about impossible to hear.
Skyline has even more horsepower with its bigger engine. I think 6 cylinder.
Caravan, is that piston engine or a turboprop?
Noise cancelling headsets take out a lot of the low frequency noise, and make things so much more comfortable. Mine are from headsetsinc.com, are not ridiculously expensive, and work great behind my 180HP engine, no mental fatigue from noise after a 3 hour flight with ATC chattering away the whole time (lots of comm's going on in the northeast with Boston, New York, Albany).