Return-Path: Received: from out014.verizon.net ([206.46.170.46] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 552116 for flyrotary@lancaironline.net; Tue, 30 Nov 2004 23:43:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=206.46.170.46; envelope-from=finn.lassen@verizon.net Received: from verizon.net ([4.12.145.173]) by out014.verizon.net (InterMail vM.5.01.06.06 201-253-122-130-106-20030910) with ESMTP id <20041201044234.IBCE1339.out014.verizon.net@verizon.net> for ; Tue, 30 Nov 2004 22:42:34 -0600 Message-ID: <41AD4BB4.3090600@verizon.net> Date: Tue, 30 Nov 2004 23:42:28 -0500 From: Finn Lassen User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax; PROMO) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: New Muffler Design (Noise reduction) References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH at out014.verizon.net from [4.12.145.173] at Tue, 30 Nov 2004 22:42:32 -0600 jbker@juno.com wrote: >Ed A wrote: > >For you sound experts, I presume if a 3DB increase represents a perceived doubling of loudness does that mean a 10 DB decrease represents an approx 3 fold decrease in perceived loudness?? > >---______________________________________________________ > >Do not claim to be a noise expert, but did some measurements on the P&W jets over the years. If you cut the noise 10 Db, I think that is 1/8 the perceived noise (1/2X1/2X1/2= 1/8) > >Bernie > 1/8 would be -9dB. 1/10 would be -10dB. dB = 10 * log(ratio) 10 * log(1/10) = 10 * -0,1 = -10dB. Had enough? Finn (need to do the airplane annual before I can fly it again)