How can you characterize the effect of stress on vowel sounds?

Stress significantly influences vowel sounds, primarily by altering their quality and clarity. When a syllable is stressed, the vowel it contains typically becomes more distinct or prominent, which is often referred to as vowel reduction in unstressed positions. In a stressed syllable, vowels may be pronounced more accurately, with clearer articulation and increased acoustic energy, resulting in a fuller, more resonant sound.

This phenomenon is critical in distinguishing meaning in spoken language, as stressed vowels can impact word recognition and intelligibility. For example, in English, the difference between "record" as a noun (where the first syllable is stressed) and as a verb (where the second syllable is stressed) hinges on the quality and clarity of the vowels involved.

While other options mention aspects of vowel sound characteristics, such as length, volume, or negligible effects, these do not fully capture the profound impact that stress has on the overall sound and perception of vowels in speech. Thus, the choice that emphasizes the alteration of quality and clarity best represents the essential relationship between stress and vowel sounds.