Sound has been around for a long time in the world of railway modelling, but the advent of DCC made it a realistic goal for even the beginner to the hobby.

On the McKinley Railway, sound plays a key part in recreating the feel of British railways as they moved through the years between the mid-1950s and the mid-1970s.

It wasn’t only the types, liveries and look of the rolling stock which changed out of all recognition in those two decades; their sounds changed dramatically too, with steam giving way to diesel being the most obvious example. And so capturing and reproducing these changes became a high priority for the McKinley team.

Putting cost considerations aside, it would be fairly straightforward to buy a fleet of factory sound-equipped locos and set them to work on the railway without making any adjustments at all.

But that isn’t especially realistic (and can actually be pretty annoying, to be honest). You could take things to the next stage and make any number of adjustments to each loco, perhaps by using a throttle or making more subtle tweaks via computer software. JMRI’s Decoder Pro is a good tool for this.

However, that can only take you so far, and especially so when you consider that commercial sound files were designed for use with a person operating a throttle, not a computer. In effect that means that the response of the sound file to a computer handing out the instructions doesn’t always appear realistic.

Here’s an example. A throttle controlling a steam loco is increased. You get a powered 'chuffing' sound. Decrease the throttle, and you get the 'clank clank' sound of coasting.

But that won’t necessarily happen when a computer takes charge. The computer, using Train Controller software, may send a train into a pre-determined block of track which carries a speed restriction. As the computer throttle is decreased the 'clank clank' sound comes on and stays on. This wouldn’t be right if the train was meant to be under normal power.

So that was the challenge. What then, was the solution?

We examined the structure of the sound files themselves using Loksound software (our preferred sound chip is the LokSound 4). The structure is a flow diagram which can cause different sounds to be emitted at different times with different inputs. This structure and thus its capability were adapted to suit our specific requirements which were to optimise the output of the sound files for computer, rather than human, control.

Consider this development example. Drain cocks are blown as a locomotive pulls away. A commercial file just won’t do it. So we created two artificial modes: ‘Normal’ and ‘Alternate’. Normal is the regular powered 'chuffing' sound. Alternate has the drain cocks blowing at the same time as the chuffing.

A condition (or timer) runs; under this condition if the locomotive has been stationary for a certain period of time the alternate mode will become operational. The engine pulls away with its drain cocks hissing, and they continue to hiss until the locomotive reaches a pre-determined speed step, at which point the sound file switches from alternate mode back to normal, which effectively switches off the drain cocks.

ESU Loksound File Editor

If the locomotive has been stationary for less time that the specified limit the sound file will stay in normal mode, and the noise of the drain cocks will not be heard because, back in the real world, they wouldn’t have been used.

On a broader level, McKinley locomotives have their default sounds set at different levels. This is also true of the range of sounds any specific loco will emit. For example, we often lower the ‘idle’ and ‘random sounds’ volume levels to around a third of ‘running’ volume.

Having developed and established the changes, we established a standard which set the assignment of sounds to the function buttons on the layout’s throttles.

Examples of this include: button one turns on sound, two gives as sustained horn, three is a short horn, nine is the uncoupling function, and so on.

One other point to consider when thinking about a consistent output of sound across the railway is that the computer system which drives mainline traffic is extremely dependable when it comes to issuing functions at specific locations. It is much better than any throttle-touting human could be, especially as its tasks have to be executed quickly and precisely.