Unlike instruments woven into the melodic texture of kirtan, the nagara's role at a gurdwara is closer to a public bell or a horn: a pair of large kettledrums struck to announce that something is beginning, whether the morning opening of the scripture, a wedding, or a major festival gathering. Its sound is loud, low and carrying by design, meant to reach a community rather than accompany a hymn, and it is typically played in short bursts at the relevant moment rather than continuously through a service.
The instrument itself, a matched pair of hemispherical kettle shells with a stretched hide head, struck with sticks, is shared in form with court and military kettledrums across South Asia, and its adoption into Sikh practice carries that history deliberately rather than by accident, a martial instrument repurposed as a devotional and civic signal rather than one stripped of its original associations. Because that signal function matters more than musical nuance, the instrument tolerates being played by a rotating set of designated seva volunteers rather than requiring a dedicated professional musician, in contrast to the trained accompanists expected for kirtan itself. Gurdwara committees generally schedule its use rather than leave it to spontaneous playing, since an unscheduled drumbeat at full volume can otherwise be mistaken by the wider neighborhood for an alarm rather than an invitation.