Speech Graffiti Habitability: What Do Users Really Say?

The Speech Graffiti interface is designed to be a portable, transparent interface for spoken language interaction with simple machines and information servers. Because it is a subset language, users must learn and adhere to the constraints of the language. We conducted a user study to determine habitability and found that more than 80% of utterances were Speech Graffiti-grammatical, suggesting that the language is acceptably learnable and usable for most users. We also analyzed deviations from grammaticality and found that natural language input accounted for the most deviations from Speech Graffiti. The results will suggest changes to the interface and can also inform design choices in other speech interfaces.