Re: [Harp-L] School survey help needed

[Vern <jevern@xxxxxxx>]

I haven't seen your designs, but I doubt that any of them will be effective.

You will have great difficulty designing an effective muffler for the harmonica.
The sound level of a tightly hand-cupped diatonic will be about as quiet as you can get with any practical attachment.

The human ear has a logarithmic response.  A 30 db reduction in perceived sound would require reducing the transmitted sound energy to 1/1000 of its normal level.  There is a story (possibly true) about the GE engineer who promised his boss to reduce the sound energy from a jet engine by 50%.  He did it, but the engine didn't sound perceptibly quieter.

Go out to the garage and practice in the car.   

A porous surface like cane board suppresses reflection of sound but mass like masonry is required to suppress transmission.    
A double layer of wallboard (lots of mass) on the door to your practice room might work.  However, it must seal all of the tiny cracks perfectly.  A hole in the door the size of a quarter would be almost like leaving the door open.

Sorry to be an old killjoy but it's not me...it is the acoustical sad facts. 

Vern

> 
>  HeyY'all,
> 
>  My name is Joe Glover, i am currently in Year 12 and doing Design and technology as a subject. For my project i have chosen to design and create a harmonica muffler which makes the harmonica quiet for practicing late at night or whatever. 
> 
>  I have attached a powerpoint with a series of pictures, of the various designs that i have come up with - just the shape and ergonomics really.
> 
>  Please, if you have time could you take a look and tell me:
> 
>  1. Which one you like the most
>  2. Why you like it
>  3. What you like and dislike about each of the designs
>  4. what you would add to or take away from each of the designs.
> 
> 
>  Thankyou for your time, it should be a bit of fun for you guys too.
> 
> 
>  if anyone is interested,
> 
>  the basic design is a hollow chamber in which the re-verberate and are muffled by sound absorption material (quiet wave). I am hoping to cut down the sound by 50%. The player can still hear it perfectly because the noise comes out the holes not being played.
> 
> 
> 
>  thankyou so much,
> 
>  Cheers, Joe Glover
> 
> 
> 
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