Is there a "shock collar" that doesn't actually shock the pet, but instead just makes loud noises?

You bet there is! PetSafe has a ton of products that will help you, I sold a lot of their products back in the day and people were really happy with the results.

1) In ground cat fence, this one has shock however you can change it to beep only. What this product normally does is beep first as a warning then shock if they continue to go out of bounds. They do learn quickly, so when they hear the beep they back off.

2) Wireless fence - same concept as above however no wires required and you can bring it anywhere.

3) Vibration remote trainer - this one is tone and vibration, only downfall is that you can only control 1 cat where as the two above you can buy additional collars. The weight indicated for this product is mainly for the size of the box on the collar, they can be a bit big.

Other than that there's the option of building a Catio, now it doesn't need to be as glorious as the one below but it's by far my top choice for outdoor cats.

Catiospaces.com has a ton of blueprints for sale so you can make your own. Or you can kind of figure it out yourself just by looking at the photos.

Here's a smaller version of the Catio I posted above (you can find the blueprint on the website above):

I love these as it prevents cats from killing native wildlife, being a pest to our neighbors (pooping and destroying gardens), getting into poisons (rat/mouse poison is common), being struck by vehicles or getting killed by a larger predator such as foxes, coyotes or large birds of prey.

I live in New Zealand and have had Labrador Retrievers for the past thirty odd years. We lived in a rural area with a golf course surrounding the hill we lived on with 15 other homes. No fences other than hedges were permitted which made it difficult to contain dogs. We considered the collar type system which was not ideal because it didn't keep dogs from coming on to our property. What worked beautifully was an electric fence as used by farmers to contain sheep/cattle etc.. It is inexpensive once you have purchased the unit which from memory was around US$300-$400 dollars. Boss only got 'shocked' once. ( you need to be cruel to be kind) He avoided the fence like the plague after that, so much so, that for his last 8 years we had no power running through it. The beauty of the portable electric fence is that it is easily moved, you can have a small area, or you can have a big area, all run off the same unit. and can be run on batteries or normal power supply. It won't contain cats however!