Self-sustained musical instruments are complex nonlinear dynamical systems that are known to produce a wealth of dynamical regimes. This includes different kinds of non-periodic sounds, which are either played on purpose or avoided depending on the cultural and musical context. We investigate non-periodic sounds produced by two types of flute-like instruments, namely, an alto recorder and traditional pan-like flutes from Central Chile. We adopt a nonlinear dynamics point of view to characterize the multiphonics produced by the alto recorder and the sonidos rajados produced by the Chilean flutes. Our results unveil the common quasiperiodic nature of the two types of sound regimes and suggest that they result from a similar physical sound production mechanism. This paves the way for a better control of non-periodic sound regimes by the instrument makers.