A graphical display of air pressure changes over time is known as what?

• A. Waveform
• B. Sonogram
• C. Oscilloscope
• D. Harmonic chart

Answer: (A)

A graphical display of air pressure changes over time is best described as a waveform. In speech science and acoustics, a waveform illustrates how an acoustic signal varies over time, typically showing the amplitude of sound waves as they fluctuate. This representation allows for the analysis of various characteristics of sound, including pitch, loudness, and duration, which are essential for understanding speech and other auditory phenomena.

Although sonograms can also display sound data, they specifically show frequency content over time, providing a more detailed view of the different frequencies in a sound signal, which differentiates them from waveforms that focus strictly on amplitude changes. An oscilloscope is a device used to visualize waveforms, but it is not itself a type of graph; rather, it's the tool that may be used to create such graphical displays. Harmonic charts, on the other hand, represent specific frequency components of a signal, not the air pressure changes of the waveform over time. Therefore, the choice of waveform most accurately reflects the definition provided in the question.