How do you write the sound an ice cream machine makes?

The sound an ice cream machine makes can be described as a low, humming whirr combined with a rhythmic churning or swirling noise. You might represent it phonetically as "rrrrrrr" for the hum, followed by a soft "whir" or "swirl" as the mix is churned. Occasionally, there might be a slight clinking or clattering sound from the machine's components. Overall, it creates a soothing, mechanical melody that signals deliciousness is on the way.