studies have found that the acoustic structure of a bark "[varies] considerably with context." These studies suggest that barks are more than just random sounds, and indeed hold some sort of communicative purpose. As nuisance Bark control Nuisance-barking dogs sound off for no particular reason. "Many dogs bark when they hear other dogs barking," says Katherine A. Houpt, V.M.D., PhD, director of the Cornell Animal Behavior Clinic. Nuisance, inappropriate, or excessive barking comprises between 13 and 35 percent of behavior-problem complaints by dog owners, Houpt noted. The electric collars deliver an irritating shock of adjustable intensity when a vibration sensor in the collar detects barking. The citronella collar releases a spray of citronella when a microphone in the collar senses barking. For the eight dogs that wore both types of collars (one shepherd mix did not complete the study), all owners found the citronella collar to be effective in reducing or stopping nuisance barking and most preferred the fragrance spray. Four out of eight owners said electric shocks had no effect on their dogs—they kept on barking. The citronella collars had problems, Juarbe-D'az noted. One dog owner complained that citronella oil stained the upholstery when the dog, fond of lying about on upholstery, barked. "One owner thought the scent was preferable to her dog's body odor." Dog barking can be a nuisance and is a common problem that dog owners or their neighbors may face. Different kinds of barking often require different kinds of approach to reduction. Common approaches are: Attempting to understand, and if possible eliminate, the causes of barking. Using positive training methods to correct the behavior. Dogs may bark from anxiety or stress, so punishment can often cause problems by reinforcing a cycle of bad behavior. Positive approaches can include: Repeated exposure to stimuli whilst calming the dog and persuading it to remain quiet. Distraction as the stimulus happens, through treats, praise, or similar. Reshaping via clicker training (a form of operant conditioning) or other means to obtain barking behavior on command, and then shaping the control to gain command over silence. In her 2008 book Barking: The Sound of a Language, Turid Rugaas explains that barking is a way a dog communicates. She suggests signalling back to show the dog that the dog's attempts to communicate have been acknowledge and to calm a dog down. She suggests the use of a hand signal and a Calming