*3.2. Auralization*

While many researchers and communities have improved accessibility for the visually impaired by using sound in digital games, in the field of board games, they have designed accessible games mainly by using tactile feedback. Although some sound-based board games allow players to play against each other without relying on visual information by manipulating sound components, the idea of electronically generating sound from simple components such as cards and pieces made of paper or plastic is novel. The auditory card game system proposed in this study provides a new solution to board game accessibility by electronically generating sound from simple components. Figure 2 shows an overview of the auditory card game system. This system assumes a game with a game master. It comprises several "audible cards" and master device that is wireless connected to them. Small tablet devices, such as the iPod touch, can emit sound from individually mounted speakers. In addition, they are the same size as cards used in board games, making it easy for players to intuitively imagine them as cards. With this consideration, iPod touch devices were used for the audible cards. The audible cards correspond to the components used in the board game. The master device is a terminal operated by the game master to advance the game and make each audible card emit its sound. The audible cards hold the sound data used in the game and in our experiment. The master device operated by the game master and the multiple audible cards have a "one-to-many" type Bluetooth

communication. When a device ID and sound data are specified by the master device, the specified audible card will start playing a specified sound from its own sound set. The application was developed in Swift with "Multipeer Connectivity" frameworks. Each audible card emits its own unique sound stimulus, much like how playing cards correspond to pictures and symbols. The role of an audible card as a component of the board game is the presentation of public information. The aim of this system is to place these audible cards on the board as the game's components, as well as to make the players recognize what each card represents and the position of the card through auditory stimuli.

**Figure 2.** System overview: (**a**) a small tablet device regarded as a card: an audible card. (**b**) The game master plays an audio signal from the audible card by wireless connected device. (**c**) Players recognize the information of the card through acoustic sensation.

Auralization has been used in many solutions for improving accessibility problems for the visually impaired [27–29]. The auditory card game system works by presenting the contents of the cards through sound rather than visual information. This is a process of making audible the components of a board game that originally relied on visual and tactile modalities.
