For monitoring slow rotating, and variable speed and load plant, Schaeffler has introduced acoustic emission monitoring, from Holroyd Instruments, alongside its existing vibration-based products.

On the handheld side, it offers AE-Check – a route mode device that is easy to use and configure, with up to six routes through the plant and 435 measuring points.
Then there is AE-Pro, a semi-portable acoustic emissions system aimed at plant that doesn't warrant a fixed system, but requires more than instantaneous data collection.
This is a portable multi-channel PC Notebook-driven data acquisition and signal analysis system that captures acoustic emission signals generated by machinery and other rotating components and systems.