What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Sounds levels in an RV cockpit

Dean Pichon

Well Known Member
Hi All,

Today, for fun, I used a sound meter app (Decibel 10th by SkyPaw) on my iPhone to measure the sound level in my -4. Much to my surprise, the sound level averaged 96dB with a peak of 99dB. I had expected a value in the 80's... (Thank God for Lightspeed headsets) Has anyone else measured sound levels in their cockpits?

For comparison purposes, my -4 has an IO-360, 4-pipe Vetterman exhaust, and no sound proofing. I was running 23-squared while I held the meter (phone) at chest height during the measurement.

Thanks,
 
Hi All,

Today, for fun, I used a sound meter app (Decibel 10th by SkyPaw) on my iPhone to measure the sound level in my -4. Much to my surprise, the sound level averaged 96dB with a peak of 99dB. I had expected a value in the 80's... (Thank God for Lightspeed headsets) Has anyone else measured sound levels in their cockpits?

For comparison purposes, my -4 has an IO-360, 4-pipe Vetterman exhaust, and no sound proofing. I was running 23-squared while I held the meter (phone) at chest height during the measurement.

Thanks,

I didn't measure the decibels but I flew recently for several hours without my comfy carpet/leather interior. It's is so much noisier without the interior.
 
Cool app. I will try and report back. Do you think airspeed plays a big factor or more so the motor ? Sometimes when I get above 190mph it keys my mic so maybe for consistency airspeed and MP/ rpm should all be considered.
 
Some of those phone app sound meters can't read above 90 Db or so.
I bought a hand held Db meter off epay that reads to 130 Db, and my RV-8 is pretty loud inside.
I measured 114 DbC at about face height. I have a loud Turbocharged Mazda Rotary engine, but this was taken after I installed a muffler, which really toned it down.
I have no interior upholstery, save for Oregon Aero seats and stick boots.
At the time, I had not installed any weather stripping around the back of my canopy skirt.
The sound readings I've taken were initially DbA, until someone said I should be using the C scale, which reads a higher number.
At a medium cruise power I had a 119 DbA reading before the muffler was installed.
Dean, perhaps your Skypaw does not read above 99 Db? It might actually be louder in there.
 
I suspect that it is not keying your mic. It is probably opening the squelch circuit in your inter com. Tighten the squelch circuit up or try it in pilot isolate mode only and see if that fixes it.
 
I would question any of the smartphone apps. I've tested a few and none of them would report above 96-98 dB.

I tested my airplane, lawn mower, chainsaw, and my large belt sander (I wear hearing protection with all of these). No matter how close I measured, they all reported a peak that carried between 96-98 dB.
 
We got given vouchers for noise cancelling headsets at work for some touchy feely human remains edict. Not that an Airbus needs them !

I tried them in the RV.

....... When you buy a Ferrari, one of the attractions is that when you launch, it makes a glorious noise - when you drive through a tunnel you down shift just to hear it howl.

When I open up the RV - nice and slow - it just sounds most excellent.

Why would I spoil that with noise cancelling headsets ?

They went on eBay :D
 
Hearing

Mike,
Your response is unbelievable!

Let me tell you why you should use noise cancelling. After years of building fying aircraft, riding bikes etc, I started to get tinnitus about 15 years ago. My hearing started to deteriorate about this time. I have now lost the top range of my hearing.

Hearing conversations in crowded rooms is almost impossible, When watching TV I miss most of the dialogue. Telephone conversations are very difficult. Do I regret not protecting my hearing more......you know the answer.

I suspect at some stage it will be hearing that prevents me flying. If you do not want to be like me with two hearing aids [costing2k] protect your hearing.....especially in an RV....they are very noisy and will damage your hearing!
 
I wear foam ear plugs under my david clarks. I find it reduces the noise level very well, and the radio can still cut through and be heard.
 
Hearing loss; take care of your pet

One of the moderators in these forums indicated his family dog lost its hearing from one trip in his RV.

I have a set of Mutt Muffs, but quite frankly they have to fit a dog's head just right to be effective. Others have reported stuffing foam or cotton into the dog's ears. I would have to practice that before my dog would like it.

My dog has flown in my Cessna with Mutt Muffs, but my RV isn't flying yet. I hope I finish my RV before he gets too old to fly in it!
 
Cell phones

The reason cell phone apps are worthless in these noise ranges is that the sensitivity of the mic on phones are limited. They aren't designed to operate in this kind of environment.
 
I wear foam ear plugs under my david clarks. I find it reduces the noise level very well, and the radio can still cut through and be heard.

I did this for years - pretty much from my PPL training forward. Now, I fly with one of the popular in-ear headsets with the same end results. :)
 
Hearing Loss

Steve,
Excellent response. Thank you for pointing out what happens when we do not protect our hearing...over the long haul.
 
As an instructor I had an ENT as a student and we had a discussion about ANR. At the time, my lightspeeds were back at the manufacturer for a warranty issue and I was flying with my old DC's which are not ANR.

Long story short, he did not believe that ANR provided any actual protection from noise. Why? Most of the noise that's damaging your ears comes through your skull. Also, ANR doesn't provide any additional protection because it's adding more noise to cancel out the other stuff. He actually sold his Bose X and went to a DC ANR after his battery died one day.

His take: While it does help with fatigue, it may not help with noise protection. The best thing you can do is be vigilant, and make sure you have a headset with a good passive reduction level above all else. I don't know if there's any truth to it, but he's much more an expert on the topic than I and the result is I've done my best through years on the ramp, and flying, to make sure I have ear protection at all times when it gets noisy.
 
Bad physics

As an instructor I had an ENT as a student ...

Also, ANR doesn't provide any additional protection because it's adding more noise to cancel out the other stuff.

A half truth. ANR adds noise in the direction going away from the speaker, outward. The headset must either absorb, or transmit, this noise, not reflect it. Anr decreases noise in the direction going from the speaker towards the ear.
 
So it's a quality issue, some ANR sets make my ears feel better than using a non-ANR headset for the equivalent flight, one ANR headset I tried, my ears actually felt more tired. (cheap consumer grade stereo ANR set advertised for use in airliners etc)
 
Noise booths at the shows

I got similar 98-99 db from my iPhone in my rv7 and on my lawn mower. So maybe they are under reading. The interest point however is that I tested the noise booths at the shows and they were in the 89-90 db range. I bought a head set that worked really well in a booth at OSH and hated it in my RV. My advice is try a head set in flight before you buy.
 
Was that ent as in ear nose throat md. Or did you mean emt?
Credibility gap if you know what I mean.

Ear Nose and Throat Specialist.

As I said, I don't know if there's truth to it, I haven't done much research myself and don't claim to understand how it works (as explained above, I didn't). His point of emphasis was most noise comes in through places not protected by the headphones. I guess your skull isn't as good at noise cancelling.

With that said, the fatigue benefits I see with an ANR headset (even in a jet) have proven to me that they're worth the investment.
 
Ok, an MD. I am not sure of the physics. Vibration would be transmitted through the skull on both sides of the eardrum. That is called noise cancelling as I understand it.
 
Vibrations are coupled mechanically, lean your head against the window or sidewall to experience that effect (Hey, I get bored on airliners..). In the cockpit the sound we are trying to block is transmitted by pressure waves. In our RVs it is mostly prop pulses and exhaust pulses. ANR simply(!) measures these waves and creates an equivalent wave of opposite polarity inside the earcup, thus canceling the unwanted noise. Done correctly it does not add any noise to the result your eardrum experiences.

Your head is pretty well isolated from the airframe vibrations unless you rest it against the airframe, or cheap out on the seats...
 
Back
Top