X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-yh0-f52.google.com ([209.85.213.52] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6736020 for flyrotary@lancaironline.net; Mon, 17 Feb 2014 09:46:25 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.213.52; envelope-from=ceengland7@gmail.com Received: by mail-yh0-f52.google.com with SMTP id a41so14052542yho.11 for ; Mon, 17 Feb 2014 06:45:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type; bh=L0Y+kqDvYf0Fhc+XRZkrTI9OVElNpqXuL195foieBWs=; b=ICV+PW/Wx6aAiWeRPpOXtw3bmXq2lutaSDmyDdCgiI3nq/A8gozaXF5tP5i0a+ZPZz hNmuRHsv4E8WCBl5ZbDzE5MBVSzIG34TDpJOOqFTPIQmVFQYuWc2vioqhXBPdvqUqtUW PleUZxnl2EU3K2BwO7ERWJLY3OtK6kjEWF/WJlKokisldbNQrF8melykiVsHyeGf0vSV q7oUCpPB/i0mRE+MFnZqdtrRMQ/Y5iDrL+9OzKGTHkZif1KS5qIvTvZhkFxnMx8eedr1 X9QFvdiNfF25d8vNAK3xrjGkNVEjPOWqH5YJJUA8TSXCJ92+juJCIDm1FHTWaNWBnbGZ TdJg== X-Received: by 10.236.81.237 with SMTP id m73mr23338622yhe.29.1392648349238; Mon, 17 Feb 2014 06:45:49 -0800 (PST) Return-Path: Received: from [192.168.10.36] (adsl-98-95-183-178.jan.bellsouth.net. [98.95.183.178]) by mx.google.com with ESMTPSA id h23sm48388303yhc.0.2014.02.17.06.45.47 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 17 Feb 2014 06:45:48 -0800 (PST) Message-ID: <530220D6.1040403@gmail.com> Date: Mon, 17 Feb 2014 08:46:46 -0600 From: Charlie England User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Sound Level Testing (small world) References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------080501050501020608010401" This is a multi-part message in MIME format. --------------080501050501020608010401 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit What are the odds that two former sound techs would end up on a rotary email list? That's where I picked up my knowledge, two or three careers ago. Chris, I think he said that he's measuring in the cockpit in front of his face. And I agree with Dustin; it's very unlikely that high SPL's can be measured with a phone microphone or its electronics. They're just not designed to handle extremely loud noise, & they are unable to measure above a certain level. Charlie On 2/17/2014 7:07 AM, Dustin Lobner wrote: > 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 > 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 >> " > > 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 >> > >>> To: Rotary motors in aircraft >> > >>> 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 --------------080501050501020608010401 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit
What are the odds that two former sound techs would end up on a rotary email list? That's where I picked up my knowledge, two or three careers ago.

Chris, I think he said that he's measuring in the cockpit in front of his face. And I agree with Dustin; it's very unlikely that high SPL's can be measured with a phone microphone or its electronics. They're just not designed to handle extremely loud noise, & they are unable to measure above a certain level.

Charlie

On 2/17/2014 7:07 AM, Dustin Lobner wrote:
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

--------------080501050501020608010401--