We are using a Piezo buzzer for geneating sound from electrical signals mainly because the sine wave generator of ExpEYES cannot drive a low impedance load like a loudspeaker ($ 8\Omega $). The Piezo buzzer does not have a uniform frequency response. The amplitude of sound is maximum at the resonant frequency, decided by the dimensions and the mechanical properties of the buzzer and the cabinet housing it.
We can span the frequency and plot the intensity of sound against it. The experiment setup is shown below along with the result.