You are going to hear the water draining regardless of dishwasher brand. However, you can ensure there is no low spot in the line to the air gap (so water doesn't gurgle through the line).

Install the dishwasher drain hose over the top of the sink cabinet and get rid of the air gap. I won't tell inspection.

Bosch dishwashers have a rubber flap inside the drain line to prevent water from re-entering the unit.

From the service manual:

You're probably going to have noises coming from the drain/disposer even without an air gap involved ... but setting the drain stoppers in place may have more of an effect without the air gap also being a source.

I’m also hearing some increased drain pump motor hum compared to when the dishwasher was new which probably means it’s time for a new pump. However, the noise of air and water gurgling dwarfs that noise, so I want a solution for that problem before replacing the pump or switching to Miele.

Did you look at the line to your air gap?

The drain hose goes straight up from the bottom of the dishwasher to the air gap on the counter.

Kind of depends on what your jurisdiction requires on why it is there. If it is super annoying you can do a high water loop and get rid of the air gap. There will still be gurgling drain noise coming from the sink drain. I guess if your air gap is excessively loud for some reason then maybe worth removing but I am not sure.

The high loop or air gap is there so sink drain water doesnt end up in the dishwasher.

Thinking outside of the box, I guess you would need a nonconventional installation if you want no noise. Something similar to a washing machine standpipe setup with its own separate trap but under the sink.

Put the dishwasher drain on the outlet end of the s bend.

The following idea, which I adopted, was likely revealed on the Kitchen Forum about 2008 or so.

The idea is to use a stand pipe, like washing machines use, mounted inside the sink cabinet where there is room to bring it near to the underside of the counter. Tilt the pipe slightly so the water runs along the side. Use a trap at the bottom. Meet all the IPC regulations for this approach. See §802.1.6 to start. No other air gap is needed, as there is one at the top of the stand pipe. Mine is quite silent with a Miele Optima.

Does the dishwasher drain thru a knockout into the Garbage Disposal?

Answering Stax question above, I have same problem and, yes, empties into disposal.

just had dishwasher replaced today, previous dishwasher never made this much noise. 😞😞

I just had my Bosch dishwasher replaced with another and it drains (into the sink) so much louder than the last. I'm disappointed.

Close the drain stoppers when running it.

If possible have another drain pipe and p-trap installed just for the dishwasher and have it tied in to the sink drain below the cabinet or in the basement or crawl space. Then you won’t hear a thing. I have this set up but that drain got clogged and was error coding the DW so I tried to save money and tapped it into the sink drain under the cabinet myself and now I wish I hadn’t because the draining is very loud in the sink. I’m going to switch it back once my plumber is free to come and snake the DW drain. Lessons learned.