Grown dogs face stress and frustration at being confined and isolated for long hours. The dog may bark excessively or chew on any object it can get hold of. To overcome this separation anxiety, you need time to train it to expect you to return after every separation. Bring your dog out for regular exercise to release its pent up energy. You can also enroll it in an obedience school to overcome separation anxiety.
Dogs are frightened of loud noises and start chewing because of their fears.
You can train your dog desensitization to the noises. Gradually expose it to the fears with you around and it will eventually accept and overcome its fears. When a dog is socially isolated or bored without play things, it starts to chew for its own recreation and entertainment. Some dogs deliberately seek attention with negative behaviors. You need to reinforce your dog for the good behaviors and ignore it for the bad ones.