Acoustic tones generated by turbulent flows and shear‐layer‐instability interactions with side‐branch resonator pipes were investigated experimentally using fast Fourier transform techniques. The experimental values of resonant frequencies and instability frequencies were compared with predictions for two stages of shear‐layer interaction. Relative tonal amplitudes are shown to demonstrate cut‐in and cut‐out phenomena. The qualitative differences between turbulent‐flow‐generated tones and instability‐generated tones are also noted.