The song is unmistakable: an uninterrupted, insect-like buzzing "zrrrrrr" that can continue for several minutes on end without a break. The pitch is even and monotonous, similar to the River Warbler but slightly lower and softer. The character of the song resembles the hum of an electric motor running at low speed. The male sings readily at night and during the morning and evening hours, hidden among the reed stems.