What type of sound is typically characterized as complex in speech?

Complex sounds in speech are characterized by the presence of multiple frequencies simultaneously, which is typical for both vowels and consonants.

Vowels are typically produced by the resonances of the vocal tract, resulting in rich harmonic structures. They have a fundamental frequency accompanied by overtones, making them complex sounds.

Consonants, on the other hand, often involve turbulence or constriction at various places in the vocal tract, leading to a wide range of frequency components as well. For example, fricatives generate noise across a broad frequency range due to airstream turbulence.

When considering the entirety of spoken language, both vowels and consonants contribute complex sounds, ensuring that the correct answer encompasses both types. Silence, while an important aspect of speech for creating pauses and conveying meaning, does not produce sound and hence is not considered complex. Thus, the inclusion of both vowels and consonants as sources of complex sounds justifies the answer that indicates both are involved.