DIYAPASON-L Digest #878 - Friday, September 12, 2003
 
Re: Room response to certain organ notes
  by "F. Eugene (Gene) Dunnam" <dunnam@phys.ufl.edu>
Re: [Residence Organs]  Re: Room response to certain organ notes
  by <Kzimmer0817@aol.com>
Wyvern Organs
  by "Rev. Tony Newnham" <organist@tsnp.fsnet.co.uk>
 

(back) Subject: Re: Room response to certain organ notes From: "F. Eugene (Gene) Dunnam" <dunnam@phys.ufl.edu> Date: Fri, 12 Sep 2003 12:14:19 -0400   Greetings-   Here's a slightly edited version of the email I sent Gary on Wednesday:   ***** Hi- Interesting! No, you're not at all bonkers...I'd say that this note (D) is setting up a 'standing wave' [resonance] in the room, similar to the "singing in the shower stall' effect.   Check it out: the 16' D is 36.7 Hz. The wavelength at room temp is 1100/36.7 =3D 29.97 ft. The standing wave is probably between two large-area, sound-reflecting surfaces that are 1/2 a wavelength apart =3D close to 15 ft.   So I'm betting that your room has at least two opposite-facing, hard-surface walls that are about 15' apart, or else you have an uncarpeted floor & a 15' hard ceiling [unusual but not impossible!].   Does any of this work? Let me know!   Gene **   and his reply:   HI Gene, Wow, am I impressed. The organ chamber (my old t.v room) is exactly 15 wide and 18 feet long, 10'4"ceiling and hard plaster in my 1897 victorian. When I get this monster fully playing, it will be the largest organ in my small county in Illinois consisting of 15 ranks. Thanks for your help. Let's stay in touch. Gary   ***   Hey, physics works.   "Make a joyful noise, preferably in tune"   Gene   **************************************************** * F. Eugene (Gene) Dunnam * * Professor of Physics <dunnam@phys.ufl.edu> * * University of Florida (352) 392-1444 * * P. O. Box 118440 * * Gainesville, FL 32611-8440 * * <http://www.phys.ufl.edu/~dunnam/Welcome.html> * ****************************************************  
(back) Subject: Re: [Residence Organs] Re: Room response to certain organ notes From: <Kzimmer0817@aol.com> Date: Fri, 12 Sep 2003 12:28:18 EDT   List,   I finally decided to add a little to this discussion. It is nice to have people like physicists, doctors, dentists, etc. on lists like this because = it makes discussions more interesting.   Isn't this standing wave phenomenon the same thing as a resonant = frequency? or is that something different? We often notice that, while accelerating gradually in our car, something will start to rattle, then it will stop = after we pass thru a certain speed. I tho't that's what happens when certain = sounds on the stereo at home make things rattle.   A certain low C (8' C) would cause an A/C vent to rattle at a church in = town.   From my flying lessons, i remember reading that airplane propellers are actually tuned. Propeller blades actually move forwards and backwards as = the prop turns. It also vibrates at certain frequencies. Supposedly a prop is = tuned in a way that its resonant frequency at the usual cruising rpm is not the = same as that of stuff in the plane because that would cause all kinds of = problems.   Have a great weekend. Keith    
(back) Subject: Wyvern Organs From: "Rev. Tony Newnham" <organist@tsnp.fsnet.co.uk> Date: Fri, 12 Sep 2003 17:58:14 +0100   Hi   Does anyone know which flavour of sound generation Wyvern are using? I = heard - briefly - their temporary instrument in Arundel R.C. Cathedral, = and it sounded pretty good - just a slight "artificiallness" to give the = game away.   I'll look at their web site when I get back from holiday!!   TIA   Every Blessing   Tony