Are there any true effective ways to reduce the noise of a Mooney?

[Schllc]

Aside from a tight door seal, are there any real ways to reduce the decibel level in the Mooney?  
The only complaint I have with the plane is the noise.  I don’t know that any other single is that much better.  I mean the reality is that we are sitting on a big no power engine with nothing more than a thin aluminum body with pretty thin insulation, so it is a challenge.  
I would think thicker glass and denser insulation would make a difference, but not sure if it would make an attributable difference. 
And yes, I know about ANR headsets, but I have a problem with my ears that they only make worse.  
I would gladly give up 20 or 30# of UL to make it measurably quieter. 
Has anyone successfully done this?  If so, how and what was the decibel reduction?

[201er]

21 minutes ago, Schllc said:

Aside from a tight door seal, are there any real ways to reduce the decibel level in the Mooney?  
The only complaint I have with the plane is the noise.  I don’t know that any other single is that much better.  I mean the reality is that we are sitting on a big no power engine with nothing more than a thin aluminum body with pretty thin insulation, so it is a challenge.  
I would think thicker glass and denser insulation would make a difference, but not sure if it would make an attributable difference. 
And yes, I know about ANR headsets, but I have a problem with my ears that they only make worse.  
I would gladly give up 20 or 30# of UL to make it measurably quieter. 
Has anyone successfully done this?  If so, how and what was the decibel reduction?

By far the simplest/cheapest way is to power back in cruise. And cruise at higher altitude. I don’t think any amount of mods makes as big of a difference in volume.

You can also try double bagging. Halo under a passive set of ear muffs or ear plugs under a passive headset.

[Utah20Gflyer]

14 minutes ago, 201er said:

By far the simplest/cheapest way is to power back in cruise. And cruise at higher altitude. I don’t think any amount of mods makes as big of a difference in volume.

I agree.  There is a big difference between WOT at 2500 rpm vs 2300 rpm.   I generally cruise in the 2300-2400 rpm range.  You also save fuel which is a nice bonus.   You’d have to do a lot of work to get that same decibel drop via insulation, etc. 

[aviatoreb]

My rocket is loud - louder than most Mooneys, but it was much louder when I got it.  An expensive fix: when I switched from the McCauley 3 blade prop which was 76'' to my current MT four blade which is 74'' the sound went down significantly.  There were other important changes and reasons I did it but on the topic of sound it was notable.  It's not just the shorter prop or the four blades but a compliant prop like a MT (carbon wrapped wood) bends and scoops the air more than a metal prop that beats the air. People who stand outside my airplane while on the ground almost all say it sounds different and milder than most piston airplanes.

[Schllc]

I have no experience with mooney’s that don’t have the 550. I have a decibel meter and the difference between 2300 and 2500 was almost imperceptible. 
I was shocked how with the lycoming 540 in the Aerostar it drops significantly when you go from. 2500 to 2200. Enough to take off your headset without discomfort. 
it’s a pressurized twin so I’m not comparing overall, just the difference in the lycoming and continental. 

[Schllc]

45 minutes ago, 201er said:

By far the simplest/cheapest way is to power back in cruise. And cruise at higher altitude. I don’t think any amount of mods makes as big of a difference in volume.

You can also try double bagging. Halo under a passive set of ear muffs or ear plugs under a passive headset.

I have only had ovations and acclaims, and I can tell you power reductions just don’t reduce the sound all that much. I mean if you draw it down to approach speed with 16.5” yes, but anything less drastic just doesn’t make that much of a difference. 
 

There is a free sound app called decibel x you can download for the phone. 
see if the reduction is significant as you perceive. 
 

I think my auditory issues may make me more sensitive than other so my problem is somewhat unique. If I wear the Bose or light speed headset for a three hour flight my ears will ring for days after. I use the clarity aloft in ear headset which in addition to being more comfortable, do not hurt my ears after I land. 
headset comfort and efficacy are a very personal thing, so I’m not trying to say they are anything other than my preference. 

[Crawfish]

In my 231 it makes a large difference going from 2500 to 2300 and then even more to 2100. The plane already had the thicker glass STC installed when we bought it so I can't give you a before and after. But with RPM pulled back the plane is fairly quite. 

 

I imagine you can use the adhesive backed sound deading like Soundex to help as well if you don't already have it.

 

Before I had the money for ANR I used DC's and ear plugs underneath and that made the piston singles I was flying at the time very quite.

[Andy95W]

With regard to insulation-

I’ve owned 2 Mooneys, a 1967 M20C with the original fiberglass insulation and my current 1964 M20C that had been modified with 1” thick closed cell foam insulation. A previous owner had installed that stuff everywhere, even the firewall.

I don’t think there is any appreciable difference in noise level.  If there is, it’s 2 decibels or less.

Over the past 10 years, I’ve been replacing the 1” thick with 1/2” thick, because that foam breaks down over time and makes a mess.  Still no appreciable difference.

On my first M20C, the original fiberglass was changed for the SB 208b insulation.  If any sound reduction occurred, it was due to that exchange.

[exM20K]

44 minutes ago, Schllc said:

I have no experience with mooney’s that don’t have the 550. I have a decibel meter and the difference between 2300 and 2500 was almost imperceptible. 
I was shocked how with the lycoming 540 in the Aerostar it drops significantly when you go from. 2500 to 2200. Enough to take off your headset without discomfort. 
it’s a pressurized twin so I’m not comparing overall, just the difference in the lycoming and continental. 

In the A*, your head is pretty close to and aligned with the plane of the left prop, but you have that sturdy cabin to offset noise. So it doesn’t surprise me the difference is noticeable in that plane.  The 310 I used to fly was about the loudest plane I have ever flown for the same reason, and it didn’t have the structure of the A* to help.

Have you had the prop dynamically balanced? It’s not exactly noise that a well balanced prop reduces, but it kinda is.

-dan

[Shadrach]

16 minutes ago, exM20K said:

In the A*, your head is pretty close to and aligned with the plane of the left prop, but you have that sturdy cabin to offset noise. So it doesn’t surprise me the difference is noticeable in that plane.  The 310 I used to fly was about the loudest plane I have ever flown for the same reason, and it didn’t have the structure of the A* to help.

Have you had the prop dynamically balanced? It’s not exactly noise that a well balanced prop reduces, but it kinda is.

-dan

Indeed removing the vibration and harshness leaves just the noise. Which is a major improvement.

[Ragsf15e]

I think trying a good comfortable earplug under a comfortable passive headset is worth a try. That was the standard way we all flew in military jets because they are ridiculously loud.  It works and you can get real comfortable with it.

[Shadrach]

2 hours ago, Schllc said:

Aside from a tight door seal, are there any real ways to reduce the decibel level in the Mooney?  
The only complaint I have with the plane is the noise.  I don’t know that any other single is that much better.  I mean the reality is that we are sitting on a big no power engine with nothing more than a thin aluminum body with pretty thin insulation, so it is a challenge.  
I would think thicker glass and denser insulation would make a difference, but not sure if it would make an attributable difference. 
And yes, I know about ANR headsets, but I have a problem with my ears that they only make worse.  
I would gladly give up 20 or 30# of UL to make it measurably quieter. 
Has anyone successfully done this?  If so, how and what was the decibel reduction?

Insulated my cabin from top to bottom with half-inch closed cell foam save for the firewall, which has a blanket.  I did do the top of the instrument panel. The difference as measured with an iPhone decibel was trivial. To the naked ear it seemed marginally quieter.  I attribute this to the dampening effect of the foam. There is no background rattling or buzzing in the background. I believe the noise in Mooney is mostly generated by the prop. The tube and fabric Decathlon that I fly is far quieter than my Mooney. Some of that has to do with the fact that it won’t pull much over 2500 RPM but not all of it. It’s much quieter and idol as well… so I have to believe it has something to do with windshield proximity to prop airflow. The build quality and materials of the Decathlon are not nearly as substantial as the Mooney, yet it’s quieter. 

[dkkim73]

2 hours ago, Ragsf15e said:

I think trying a good comfortable earplug under a comfortable passive headset is worth a try. That was the standard way we all flew in military jets because they are ridiculously loud.  It works and you can get real comfortable with it.

This is a good suggestion. Certainly from a hearing protection standpoint it is a good idea. For maintaining occupational fitness (young pilots, military, etc) this is a very good idea. I'm personally skeptical modern ANR really decreases exposure; more so improves intelligibility in certain ranges. At the very least one layer of good passive attenuation seems like a no-brainer to me. 

Above idea is to double-cover with passive attenuation (so background noise further decreased), with the desired signal relatively higher as it goes through only one set of protection. You can modify this idea by using ear plugs with small channels (like shooting plugs which can pass higher frequencies for speech), or even in-ear speaker units, further boosting SNR. I believe a lot of piston-plane noise is lower to mid-range vs. turbine. 

To @Ragsf15e's example, I started with the exact same solution but saw the transition to in-ear plugs in the F-15. Those were the Westone ACCESS plugs, which aren't necessarily even the quietest, but the improvement in comms intelligibility was huge. There are a lot of civilian options on the market; I haven't tried any yet to comment. 

@Schllc , you mention a more specific issue with hearing. There are some pretty specific otologic conditions involving noise, speech discrimination, etc. Replying here in general, which might helps others,  it occurs to me that you might:

- do some experimentation with the above (affecting absolute vs. relative noise levels, frequency characteristics etc). 

- if relevant, try the Lightspeed Delta Zulu (which as I understand it allows building a specific frequency response curve). Physically great headset too, though others have reported quirks with all the fancy electronics. 

- find a thoughtful audiologist with a knowledge of some of these occupational-type issues and get a more individualized opinion, and see if there are any custom solutions

HTH

David

[Schllc]

Been to an audiologist, several actually as well as some ENT’s.  I have lost a significant amount of hearing in one ear at certain high octave levels, and overall hearing in both ears. I’m certain it’s from poor protection and the first 40 years of my life around a lot of very load noises. Guns, explosions, tools, aircraft, music, etc….

They all agreed on one thing, it isn’t getting better.  It is what it is….
The in ear type headphones really make the radio more understandable and are easier on my ears. 
I have tried the Zulu’s (actually have a pair I was considering selling), Bose a20’s, a30’s, DC, DC Pro, and a few other brands. Nothing worked as well for me as the clarity aloft. 
I did try putting a set of noise canceling on top a few times,  I didn’t notice a big difference in sound, but it sure was uncomfortable. 
I also tried earplugs under the Bose, light speed, but I missed too much of the radio for that to work. 
I’m resigned to the damage and just want to do what I can to mitigate moving forward.  
it was one of the main reasons for the Aerostar. It is the quietest piston I’ve ever flown.

[Echo]

Airplanes are noisy. Sorry you have issues that do not allow you to enjoy benefits of ANR headsets. With them flying and listening to music is a joy. I really disliked clamping force of David Clarks over a two hour flight. Non issue with Bose ANR for me. A literal game changer along with a good PS Engineering Intercom. Good luck with a workable solution. 

[FoxMike]

Noise and vibration became a big problem for me as I have gotten older. I could only manage 3 hour legs without a break. I replaced the McCauley with a four blade MT.  Cabin is quieter so that I can empty the fuel tanks without a stop.  Used to wear Bose ANRs but now use a Halo.  Very happy with the MT.  

[dkkim73]

6 hours ago, Schllc said:

.Nothing worked as well for me as the clarity aloft. 

I did try putting a set of noise canceling on top a few times,  I didn’t notice a big difference in sound, but it sure was uncomfortable. 

Good data point on Clarity Aloft. Maybe I'll try that as a first experiment with civilian in ear rigs. 

I wonder if putting passive muffs on top would work well for you...? Or amplified shooting muffs like Peltor if you're not flying solo and want to hear in cabin sounds. 

IIUC a big advantage of pressurized cabins is noise reduction. I'll bet the noise reduction strategies are different. 

[dkkim73]

Just now, dkkim73 said:

 

IIUC a big advantage of pressurized cabins is noise reduction. I'll bet the noise reduction strategies are different. 

BTW I watched American Made a few weeks ago. Makes me want an Aerostar...

[Schllc]

She flys like a big Mooney. It’s firm on the controls, loves to go rolling downhill. 
Biggest difference is how easily and quickly I can slow down. A little different sight perspective because it’s a lot higher.  But, like the Mooney, it is 100% a pilots plane. 
it’s fairly efficient as well for the capability, and just fun to fly.   

[ArtVandelay]

I used an app for my iPhone which tells me the decibel level is about 100, you may try doing that and see if there’s any hot spots where sound is coming from. I would think air vents and windshield would be the loudest.

[Andy95W]

A lot of guys here really like the QT Halo in-the-ear headsets. Less expensive than the Clarity Aloft, and in some ways better.

Plus, the founder/owner of the company is an actual audiologist and Mooney owner.

[midlifeflyer]

27 minutes ago, Andy95W said:

A lot of guys here really like the QT Halo in-the-ear headsets. Less expensive than the Clarity Aloft, and in some ways better.

Plus, the founder/owner of the company is an actual audiologist and Mooney owner.

For me, the Axis combines the qualities of both the Clarity and the Halo. Choice of Comply foam (Clarity) or 3m (Halo). The replaceable audio tubes of the Halo. And the mic actually stays in place (Clarity: the reason I rejected Halo).

BTW, if you think Mooneys are noisy, you should try a DA40 with the air vents open.

[Schllc]

1 hour ago, midlifeflyer said:

For me, the Axis combines the qualities of both the Clarity and the Halo. Choice of Comply foam (Clarity) or 3m (Halo). The replaceable audio tubes of the Halo. And the mic actually stays in place (Clarity: the reason I rejected Halo).

BTW, if you think Mooneys are noisy, you should try a DA40 with the air vents open.

Thanks, I had not heard of this headset.  I’m pretty happy with the clarity but may give this one a try. 
the da40 is the most unpleasant plane I’ve ever been in. The seats are uncomfortable with no adjustability, the rudder pedals don’t move out far enough, and it’s hot like flying inside a giant magnifying glass. It is NOT a plane for south Florida. And yes, it is really loud, with or without the vents open. 
 

[midlifeflyer]

47 minutes ago, Schllc said:

Thanks, I had not heard of this headset.  I’m pretty happy wi5 the darling bu may give this one a try. 
the da40 is the most unpleasant plane I’ve ever been in. The seats are uncomfortable with no adjustability, the rudder pedals don’t move out far enough, and it’s hot like flying inside a giant magnifying glass. It is NOT a plane for south Florida. And yes, it is really loud, with or without the vents open. 
 

My flying club has two so I spend a lot of time in them. You get used to the seats (and the ones in the newer Diesel models have adjustable backs). The horrendous noise is mostly the way the air vents are routed. I've flown an air conditioned model and it was much much quieter.  The bubble canopy and sauna effect is the main reason I bought in-ear headsets. In-ear allows for a wider variety of headgear and a the extra shade provided by a bucket or sun hat makes a huge difference. Being quieter than my Lightspeed was a bonus for me. My friends laughing at how I look in a bucket is a bonus for them. 

BTW, he doesn't advertise them but if you watch Martin Pauly on YouTube, he flies with an Axis.

[LANCECASPER]

Whichever of the in-ear models allow you to use molds to get earplugs for your own ears (perhaps made through an audiologist's office) might be the best way to reduce noise where it counts - the noise which is allowed to enter into your ears.