Quiz time! - What am I playing
 

On Sun, 18 Nov 2007 03:36:11 GMT, "Ian Iveson"
wrote:

Don Pearce wrote:

It was Paul Hogan in Crocodile Dundee, and the instrument
that
intrigued my niece was the bullroarer he used to call his
aborigine
friends from up on the ridge. It is extremely noisy!

Here's the one I made today:

http://81.174.169.10/odds/roarer.jpg

The small purr after each big roar is caused by it
rotating backwards
as it unwinds the string ready for the next yell.

I guess everyone knew but was too embarrassed to say.

What's it made of, and what shape must it be? Is it always
the same frequency and period?

Ian


It was made from a piece of tree wood carefully selected for its fine
acoustic properties. It must be exactly that shape - whatever it was.
It just needs a bit of an aerofoil on each edge to get it spinning.
The D Sharp seems to be pretty much the note of choice.

Mainly though it is the feel of the thing. A very silky, sensuous lump
of wood.

d

--
Pearce Consulting
http://www.pearce.uk.com

Quiz time! - What am I playing
 

In article , Don Pearce
scribeth thus
On Sat, 17 Nov 2007 16:27:15 -0000, "Keith G"
wrote:


"Don Pearce" wrote in message
...
My little niece is staying with me, and for fun I made this for her
today, because she saw it in a film and thought it was really cool.

So here's the question. Who was the star of the film?

And for your supplementary, what is it?

Piccy later, when you've guessed.

http://81.174.169.10/odds/mystery.mp3



A length of hosepipe and whirling it round while blowing through it (or
the vacuum cleaner hose)....???

(Either way, stop ****ing about! :-)


Nope, but warmish.

And what else are you supposed to do on a Saturday afternoon than ****
about?

d


Well I hope your little niece isn't reading these posts then!...
--
Tony Sayer

Quiz time! - What am I playing
 

On Sun, 18 Nov 2007 12:54:16 +0000, tony sayer
wrote:

In article , Don Pearce
scribeth thus
On Sat, 17 Nov 2007 16:27:15 -0000, "Keith G"
wrote:


"Don Pearce" wrote in message
...
My little niece is staying with me, and for fun I made this for her
today, because she saw it in a film and thought it was really cool.

So here's the question. Who was the star of the film?

And for your supplementary, what is it?

Piccy later, when you've guessed.

http://81.174.169.10/odds/mystery.mp3



A length of hosepipe and whirling it round while blowing through it (or
the vacuum cleaner hose)....???

(Either way, stop ****ing about! :-)


Nope, but warmish.

And what else are you supposed to do on a Saturday afternoon than ****
about?

d


Well I hope your little niece isn't reading these posts then!...

She's twelve and her vocabulary has by now extended to the Anglo
Saxon, Middle English isn't far off. But no, she isn't seeing this
stuff, she's very nice and swearing isn't part of her day-to-day
vocabulary. She reserves it for situations that really demand it.

This morning I found her a load of aboriginal patterns so she could
paint the bullroarer, but she has refused; she thinks the wood looks
too nice as it is. There is hope for the younger generation after all,
maybe?

d

--
Pearce Consulting
http://www.pearce.uk.com

Quiz time! - What am I playing
 

Don Pearce wrote:

It was made from a piece of tree wood carefully selected
for its fine
acoustic properties. It must be exactly that shape -
whatever it was.
It just needs a bit of an aerofoil on each edge to get it
spinning.
The D Sharp seems to be pretty much the note of choice.

Mainly though it is the feel of the thing. A very silky,
sensuous lump
of wood.

I particularly wondered from your description why the blade
should favour one direction of rotation. According to this

http://www.didjshop.com/austrAborigi...nstruments.htm

it doesn't. But then the article also says the frequency of
the sound is 1 or 2 Hz, which can't be right. There are 3
frequencies involved, arising from the period of the sound
repetition, the period of the arm-whirling, and the whirling
of the blade.

If you fixed a swivel to its nose...perhaps one procured
from a fishing tackle shop...would the sound be continuous?
Then the frequency could be maintained and controlled by the
speed of arm-whirling.

cheers, Ian

Quiz time! - What am I playing
 

On Sun, 18 Nov 2007 14:59:51 GMT, "Ian Iveson"
wrote:

Don Pearce wrote:

It was made from a piece of tree wood carefully selected
for its fine
acoustic properties. It must be exactly that shape -
whatever it was.
It just needs a bit of an aerofoil on each edge to get it
spinning.
The D Sharp seems to be pretty much the note of choice.

Mainly though it is the feel of the thing. A very silky,
sensuous lump
of wood.

I particularly wondered from your description why the blade
should favour one direction of rotation. According to this

http://www.didjshop.com/austrAborigi...nstruments.htm

it doesn't. But then the article also says the frequency of
the sound is 1 or 2 Hz, which can't be right. There are 3
frequencies involved, arising from the period of the sound
repetition, the period of the arm-whirling, and the whirling
of the blade.


1 to 2Hz is the pulsation - the modulation produced by the rotation
around the body, not the frequency of the sound. As for the preferred
direction of rotation, that was a tweak of my own. I found that if it
was symmetrical it would only fire up periodically, but by introducing
a slight but deliberate bias in one direction it always gets humming
instantly.

If you fixed a swivel to its nose...perhaps one procured
from a fishing tackle shop...would the sound be continuous?
Then the frequency could be maintained and controlled by the
speed of arm-whirling.


I think I'll leave that for another...

d

--
Pearce Consulting
http://www.pearce.uk.com