Last summer I was talking with a friend who plays taiko (a Japanese type of drum, which was often used in the past for communication during battles or to call the villagers to a gathering): they were telling me that they were in a remote farm to practice, hoping to not bother anybody. Well, not even after 10 minutes of practice, the farmer from the neighboring farm, on the other side of a small hill, came asking if they could stop because they were scaring their horses.
Considering also the effect which New Year fireworks have on dogs, cats and other domestic animals, it corroborates the idea that loud and sudden sounds are effective at scaring animals, in particular those with a sensitive hearing.
So, you can go for a drum, which can be made by simply carving a tree trunk, and maybe tensioning a skin on one end.
However, mind that it can turn against you: an animal can easily associate the noise with food, and then it would act as a call. For example crows in my garden have learned that the door opening around lunch time means crumbles on the tiles and are not scared any more. Therefore you would need to avoid creating a pattern.