neighbour complain again

Salmon is 9 years old now and she still bark at the cleaning lady every morning. The juristic office send letter again. Second time this month. Mom say we must keep her inside the room when we go out, but Salmon is old and she cannot hold it that long. I feel bad. Leo (my other dog) is not barking, he just sleep. Dachshund never bother anyone. But the neighbour on 5th floor say all dog bark same. Ha. We buy the white noise machine from Lazada and put it near the door. Salmon ignore it. Okay, not really working, but at least it cover some sound. If anyone have tips for old dog that bark in the condo please tell me.