  A distinguishing feature of active particles is the nature of the
non-equilibrium noise driving their dynamics. Control of these noise properties
is, therefore, of both fundamental and applied interest. We demonstrate
emergent tuning of the active noise of a granular self-propelled particle by
confining it to a quasi one-dimensional channel. We find that this particle,
moving like an active Brownian particle (ABP) in two-dimensions, displays
run-and-tumble (RTP) characteristics in confinement. We show that the dynamics
of the relative orientation co-ordinate of the particle maps to that of a
Brownian particle in a periodic potential subject to a constant force, in
analogy to the dynamics of a molecular motor. This mapping captures the
essential statistical characteristics of the one-dimensional RTP motion.
Specifically, our theoretical analysis is in agreement with the empirical
distributions of the relative orientation co-ordinate and the run-times
(tumble-rates) of the particle. Finally, we explicitly control these emergent
run-and-tumble like noise parameters by external driving. Altogether, our work
illustrates geometry-induced tuning of the active dynamics of self-propelled
units thus suggesting an independent route to harness their internal dynamics.
