Which of the following statements about formant frequencies is true?

Formant frequencies are indeed acoustic properties that play a crucial role in distinguishing various vowels. Formants are resonant frequencies of the vocal tract and are primarily influenced by the shape and configuration of the vocal tract during speech production. Each vowel sound has a unique pattern of formant frequencies, which are depicted on a spectrogram. This distinct pattern allows listeners to perceive different vowel sounds clearly. For example, the first and second formant frequencies are particularly important for identifying vowels, as they convey critical information about tongue height and backness.

The other statements do not accurately reflect the role and characteristics of formant frequencies. They are not always visible on waveforms, as waveforms represent amplitude over time rather than frequency content. While formants can affect consonant perception, they are primarily associated more with vowel sounds. Moreover, formant frequencies are influenced by vocal tract length; longer vocal tracts typically produce lower formant frequencies compared to shorter vocal tracts. Thus, the correct statement is that formant frequencies are the acoustic properties that distinguish various vowels.