In speech science, the term 'source spectrum' refers to what?

The term 'source spectrum' specifically pertains to the distribution of frequencies generated by a sound source, which in the context of speech science often refers to the frequencies produced by vocal fold vibration during phonation. This spectrum represents how much energy is present at each frequency, which contributes to the unique tonal qualities of a person's voice, known as the timbre.

Understanding the source spectrum is critical because it provides insights into how different frequencies interact when the sound waves travel through the vocal tract, ultimately shaping the resulting speech sounds. The concept of a source spectrum allows researchers and clinicians to analyze and interpret the characteristics of voice and speech disorders or to improve voice quality in therapy.

In contrast, the other options refer to different concepts in speech science, such as the observable characteristics of sound waves or the temporal fluctuations of pitch, which do not specifically describe the frequency distribution related to the sound source.