Nearly all the dialogue in the series is in an invented grammelot "penguin language" referred to as 'Penguinese', consisting of babbling, muttering, and the titular character's characteristic sporadic loud honking noise, which can be popularly recognized as "Noot noot!" or other variants, stated to be "Noo, Noo!" by the defunct Pingu website's trivia page, accompanied by turning his beak into a megaphone-like shape. Within the first 4 series, all the characters were performed by Italian voice actor Carlo Bonomi, using a language of noises that he had already developed and used for the earlier Osvaldo Cavandoli's series "La Linea". In series 5 and 6, the Pingu cast was jointly voiced by David Sant and Marcello Magni.