The screaming balloon: predicting the sound produced by a hex nut inside a balloon Henrique Ferreira, Matheus Pessoa, Ricardo R. Gitti, André J. Ferreira-Martins, Gustavo de Souza, Andrius Dominiquini, Lucas Coimbra and Lucas Rios Emergent Scientist, 3 (2019) 7 Published online: 12 September 2019 DOI: 10.1051/emsci/2019006