We have an electric forktruck that is extremely quiet and can be difficult to hear approaching even when in close proximity. In addition to lighting and frequent use of the horn, are there any types of devices that will increase the noise of the truck (whether it's mechanical or an artificial noise) so a worker can hear it approaching more easily? I've seen things like newer white noise backup alarms, but I'm not sure these would work or are designed to be going at all times. We'd also be concerned about the noise being an annoyance or distraction to the operator.