Model Railroading > Stationary sound question

I'm in the early planning stages of a switching layout I hope to start building this winter.  Being a switching layout, it will feature some tight curves.  In the interest of helping bring the layout to life, I'd like to replicate the sound of flanges squealing as the trains go around the curves. 

The way I envision it is, having 3-4 optical detectors (hence no need to mess with adding detection blocks in the track itself) spread through the length of the curve, and have the detectors wired to the input on some kind of sound module, with a small speaker hidden inside a nearby structure.

So my question is, how would I go about doing so?  Is there a commerical product that would produce a pre-recorded sound when activated by the detectors?  (I can get the sound file myself, whether it be lifted off a Youtube vid or I just go record it myself at a nearby yard.)

thanks in advance

I think these Iowa Scaled Engineering products might fit the bill:

http://www.iascaled.com/store/ModelRailroad/CKT-SQUEAL
http://www.iascaled.com/store/ModelRailroad/CKT-IRSENSE

I've been using ISE's wireless fast clock system for a couple years now and couldn't be happier.

Joe Atkinson
Council Bluffs, IA
www.iaisrailfans.org/../Sub4WestEnd

This product "Brasshat sound recorder" plays whatever sounds you've recorded into it.  It can be activated by pushbutton or you can attach your detectors to a relay to engage it.
http://bouldercreekengineering.com/brasshat.php