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[166.147.100.204]) by mx.google.com with ESMTPSA id gd5sm31305479igd.5.2014.02.17.05.07.50 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 17 Feb 2014 05:07:51 -0800 (PST) Subject: Re: [FlyRotary] Re: Sound Level Testing References: From: Dustin Lobner Content-Type: multipart/alternative; boundary=Apple-Mail-A05712EB-C227-43C3-BD4D-5DE49711D015 X-Mailer: iPhone Mail (11B511) In-Reply-To: Message-Id: Date: Mon, 17 Feb 2014 07:07:47 -0600 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-A05712EB-C227-43C3-BD4D-5DE49711D015 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Pretty sure the iPhone can't go over 90. I had an app on mine and I was in a= situation where I KNOW we were over 90 (I'm a former sound board technician= ) and it just stayed pegged at 90. Dustin Lobner > On Feb 17, 2014, at 5:43 AM, Chris Barber wrot= e: >=20 > =46rom how far away are these numbers? On my unmuffled pusher, IIRC, I wa= s getting around 90db at about 20 feet. That being said, and I could be way o= ff on distance, I will try to remember to retest, but I am using an iPhone a= pp.=20 >=20 > Chris.=20 >=20 > Sent from my iPhone 5 >=20 > On Feb 16, 2014, at 19:56, "shipchief@aol.com" wrote: >=20 >> Charlie; >> You are so correct! And I re-read that several times before I hit "send".= >> 119.7 >> 116.8 >> 114.6 >> I'm using the first scale that the devise defaults to when started. 30-13= 0 DBa. I think it has a 80-130 scale, and I can select DBc too, so I'll do t= hat. >> Sorry, but I'm glad you caught it and added the detail on A & C scale. >> Of course, those readings are averages, they were varying a bit and I had= to pick a number. I hold it so the video cam can pick it up and I can revie= w it. >> -----Original Message----- >> From: Charlie England >> To: Rotary motors in aircraft >> Sent: Sun, Feb 16, 2014 5:39 pm >> Subject: [FlyRotary] Re: Sound Level Testing >>=20 >>> On 2/16/2014 4:09 PM, shipchief@aol.com wrote: >>> I bought a Wensn 30-130 Decibel sound meter off fleabay. I use it to rec= ord sound levels in front of my face in flight. >>> I first tested my RV-8 after installing a turn down tip, but was also e= xperiencing severe exhaust leaks from my turbo: 19.7 DBa=20 >>> After fixing the leak, I recorded 16.8 DBa >>> Then I squeezed the turn down tip to a flattened rectangle opening, and r= eplaced the lost area with 1/4" holes, which I bent to face backwards with a= Philips screwdriver. a Piccolo Pipe, as it's known. Kind of a cheese grater= for sound waves. Next reading: 14.6 DBa >>> This is still to loud for my worn out ears, so I bought an Aeroturbine 2= 525 muffler, as described on this forum. I've been collecting 304 stainless p= ipe bend, ball joints clamps and hangers. I hope to get something cobbled to= gether this weekend. >> I, too, am looking forward to your report on how well it works.=20 >>=20 >> Suggest checking what's going on with your dB readings, though. 16 dB is q= uieter than a bedroom at night, & likely inaudible to those of us who have b= een flying for a decade or two. Realistic levels expected in the cockpit of a= homebuilt will be between 85 dB (pretty good, but still loud) & 120 dB (lou= d rock concert levels and painful to most of us). >>=20 >> I'd also suggest using the C scale instead of the A scale. The A scale is= very commonly used, but it presents a very distorted view of the actual sou= nd level. It radically filters the low end of the spectrum, and to a lesser e= xtent, the high frequencies, as well. It will mask the level of your actual n= oise exposure, especially at the low end of the noise spectrum. >>=20 >> Charlie --Apple-Mail-A05712EB-C227-43C3-BD4D-5DE49711D015 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit
Pretty sure the iPhone can't go over 90.  I had an app on mine and I was in a situation where I KNOW we were over 90 (I'm a former sound board technician) and it just stayed pegged at 90.

Dustin Lobner


On Feb 17, 2014, at 5:43 AM, Chris Barber <cbarber@texasattorney.net> wrote:

From how far away are these numbers?  On my unmuffled pusher, IIRC, I was getting around 90db at about 20 feet. That being said, and I could be way off on distance, I will try to remember to retest, but I am using an iPhone app. 

Chris. 

Sent from my iPhone 5

On Feb 16, 2014, at 19:56, "shipchief@aol.com" <shipchief@aol.com> wrote:

Charlie;
You are so correct! And I re-read that several times before I hit "send".
119.7
116.8
114.6
I'm using the first scale that the devise defaults to when started. 30-130 DBa. I think it has a 80-130 scale, and I can select DBc too, so I'll do that.
Sorry, but I'm glad you caught it and added the detail on A & C scale.
Of course, those readings are averages, they were varying a bit and I had to pick a number. I hold it so the video cam can pick it up and I can review it.
-----Original Message-----
From: Charlie England <ceengland7@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, Feb 16, 2014 5:39 pm
Subject: [FlyRotary] Re: Sound Level Testing

On 2/16/2014 4:09 PM, shipchief@aol.com wrote:
I bought a Wensn 30-130 Decibel sound meter off fleabay. I use it to record sound levels in front of my face in flight.
 I first tested my RV-8 after installing a turn down tip, but was also experiencing  severe exhaust leaks from my turbo: 19.7 DBa 
After fixing the leak, I recorded 16.8 DBa
Then I squeezed the turn down tip to a flattened rectangle opening, and replaced the lost area with 1/4" holes, which I bent to face backwards with a Philips screwdriver. a Piccolo Pipe, as it's known. Kind of a cheese grater for sound waves. Next reading: 14.6 DBa
This is still to loud for my worn out ears, so I bought an Aeroturbine 2525 muffler, as described on this forum. I've been collecting 304 stainless pipe bend, ball joints clamps and hangers. I hope to get something cobbled together this weekend.
I, too, am looking forward to your report on how well it works.

Suggest checking what's going on with your dB readings, though. 16 dB is quieter than a bedroom at night, & likely inaudible to those of us who have been flying for a decade or two. Realistic levels expected in the cockpit of a homebuilt will be between 85 dB (pretty good, but still loud) & 120 dB (loud rock concert levels and painful to most of us).

I'd also suggest using the C scale instead of the A scale. The A scale is very commonly used, but it presents a very distorted view of the actual sound level. It radically filters the low end of the spectrum, and to a lesser extent, the high frequencies, as well. It will mask the level of your actual noise exposure, especially at the low end of the noise spectrum.

Charlie
--Apple-Mail-A05712EB-C227-43C3-BD4D-5DE49711D015--