The Roar of an estrous female is often preceded by a series of short pulsated growling sounds as she Runs-Away from pursuing males. This Estrous-Running-Rumble typically develops into a pulsating Estrous-Roar. Sometimes the two calls are joined without inhalation in a combination call referred to as an Estrous-Running-Rumble-Roar.
References: Poole 2011. (Full reference list)
This behavior occurs in the following context(s): Advertisement & Attraction, Courtship