Double downstep in Northern Toussian: Implications on tonal representation

Abstract This article describes and analyzes double downstep in Northern Toussian (Niger Congo; Burkina Faso), a phenomenon whereby downstep occurs twice at the same position in the utterance, leading to a precipitous drop in pitch. I argue that this is caused by two separate effects: 1) a prosodically conditioned boundary effect, as well as 2) an instance of grammatical tone. Each of these processes cause downstep, and when both of them target the same syllable, their effects are cumulative. I show that the mechanisms by which double downstep arises in Northern Toussian are distinct from those in other languages with double downstep, such as several Eastern Grassfields languages (Voorhoeve 1971; Hyman and Tadadjeu 1976) and two Western Nilotic languages (Hieda 2010, 2011). I argue that Northern Toussian double downstep cannot effectively be accounted for using tonal primitives, and instead I analyze it with a model of tonal representation based on Register Tier Theory (Snider 1990, 2020). Like Register Tier Theory, the model employs the tonal features L and H as well as the register features l and h. It differs in that, rather than modeling downstep in terms of spreading and delinking of register features, multiple register features can stack onto a single tone without delinking the existing register feature, and downstep occurs for each register feature associated with a tone beyond what is lexically specified. I show that this model is well equipped to straightforwardly account for basic tonal processes like automatic and nonautomatic downstep, as well as rarely attested phenomena like double downstep.