Hi,
I continue trying to work on my N gauge layout and this topic reminded me of having seen the SMALL SCALE, BIG SOUND article in Model Rail 168/Spring 2012, the notion of adding this form of sound more than the other aspects of DCC to the layout appealed given my perceived limitations in the on-board quality of sound in the scale even with more recent improved products, the space available just doesn't allow the sound I hope for.
I had a look at the website which includes the description and a video, then emailed a couple of queries to Paul Lawton who very kindly responded in timely fashion with reassurances regarding those uncertainties.
I've only run a small test track with a single loco at a time, further testing will continue when I am able.
Regards, Gerry.