Ultra Quiet Dishwashers

I just moved in to a house that has an extremely quiet dishwasher. So quiet that when I'm standing within a foot of it, I can't hear it running AT ALL. It's so quiet that it projects a red light on the floor to let you know if it's running or not. But how??? Why can't I hear water spraying around and suds being churned and whatever else normally goes on in there?
Multiple factors—both mechanical and structural—are involved in reducing noise output in today’s dishwashers [1].Insulation: The quality and amount of insulation placed around the exterior of the dishwasher significantly impacts noise output [1].Tub materials: A dishwasher with a stainless steel tub is generally quieter than dishwashers with plastic tubs [1]. Additionally, sound dampening on the outside of the tub helps to decrease noise [1].Disposal feature: Models with food disposals will be noisier than models without [1]. Many dishwashers now use a food trap system instead that is easy to clean and results in quieter dishwasher operation [1].Water Movement: As water is pumped into the dishwasher, cycled through, and pumped out again, it can contribute to much of the sound you hear [1]. Many dishwasher manufacturers have developed solutions that minimize these sounds with innovations to wash cycles, the amount of force and speed used to spray water, and quieter pump systems [1].
The basic construction of your dishwasher, how it was built, and what materials it was made of all play a role in the sound level it reaches when it is running [2]. Dishwashers contain insulation in the sides and front of the machine, and the higher the quality of the insulation, the lower the decibel rating will be [3]. Likewise, the thicker the insulation is also plays a role in lowering the decibel rating [3]. As an extra benefit, better insulation can also increase the energy efficiency of your machine [3]. If you already own an older model dishwasher or a machine that is too loud, you can purchase sound-deadening material, similar to insulation, which is wrapped around the top and sides of the dishwasher, helping to reduce the noise and make a quieter kitchen [3]. Dishwashers with stainless steel interiors are a popular choice, and although they can be more expensive upfront, they are much quieter than models with plastic tubs [3]. Stainless steel tubs are more capable of absorbing sounds from the water spraying around inside the unit [3].