Despite ongoing research, many aspects of dogs' vocal communication are not yet fully understood, including how they convey information about items. The aim of the present exploratory study was to determine whether dogs vocalize differently toward their owner and food in an unsolvable task where food is inaccessible and to characterize the acoustic composition of canine vocalizations. In Savalli et al. (2014; 2016), food was placed in an inaccessible location with the dog present. Next, with the owner present, the communicative modalities of the dogs were recorded, including their vocalizations. Only 21.6 % of the fifty-one dogs vocalized (11 dogs out of 51; 189 vocalizations); 32.27% of the vocalizations were whines and whine-related, and 67.72% were barks and bark-related. Vocalizations may thus be a secondary modality of communication or, more likely, most of the dogs had previously learned from their owners not to vocalize in food-request situations by lack of reinforcement. We characterized four types of whines and five types of barks, respectively making up 1/3 and 2/3 of the vocalizations recorded. No other type of vocalization was found. We found firstly that the majority of the vocalizations (67.7%) were directed at the owner. Secondly, whines were rarely directed at food. Thirdly, though fundamental frequency (F0) and duration did not statistically differ for each type of vocalization, whether directed at the target or at the owner, we found a tendency of specific sub-unit of a bark to have a higher F0 and lower duration when dogs gazed at the target compared when the gazed at the owner. This type of vocalizations was thus not used similarly according to the target viewed, indicating that dogs employ different types of vocal coding to call for attention. Given the small number of dogs who vocalized in this study, future studies will involve a larger group of dogs who will be tested outdoors with an inaccessible toy to enable more vocalizations. This exploratory study opens perspectives in understanding needs expressed by dogs.