Human speech production—respiration, phonation, and articulation relies on forcing air through intricately tuned and positioned vocal folds to produce the fundamental frequency (F0) and corresponding harmonics (H2-H12). This energy creates the formants through filtering or changes in the resonances of the vocal tract during speech, singing, and utterances, especially from the pharyngeal-oral-nasal cavities.
The F0 anchors sound contrast and functions as the carrier frequency for all subsequent related events. These low- frequency events are central to the understanding of speech, particularly in background noise. Verification tests to qualify the low-frequency response is an important part of achieving a better outcome when fitting hearing aids.
Voicing features such as pitch, timbre, and timing must be perceived to be successful at understanding speech, according to Anderson and Kraus. It has been repeatedly shown that the F0, harmonics, and temporal characteristics (onset, offset, and phoneme transitions) are important for distinguishing an individual’s speech patterns from others in background noise, especially for seniors.
