A waveform is a graphical image of a signal such as an acoustic signal or Laryngograph signal. It shows the changes in amplitude of the signal with time. The amplitude is reflected in the height of the signal measured vertically (y-axis), while time is measured on the horizonal axis (x-axis). The amplitude reflects the relative change in loudness of the acoustic signal or the conductance of the tissues in the Laryngograpgh signal. Measuring the time to complete one vibratory cycle (period) allows us to calculate the fundamental frequency (Hertz). Note that the fundamental frequency can be calculated from either the acoustic or Laryngograph signals.