The average spectrum of speech is mimicked by which type of noise?

The correct answer is that the average spectrum of speech is mimicked by filtered broad band noise. This type of noise is designed to simulate the frequency characteristics of natural speech, which contains a wide range of frequencies, but it is typically represented in a more controlled manner.

Filtered broad band noise consists of sound waves across a broad frequency range that are then manipulated using filters. These filters can be tailored to emphasize or attenuate certain frequency bands, thus resembling the distinctive spectral properties of speech. Speech primarily contains frequencies in the 250 Hz to 4000 Hz range, where important phonetic information resides. By filtering broad band noise, it becomes more similar to the average spectrum of speech, providing a realistic auditory environment that can be useful for auditory training or hearing assessments.

In contrast, narrow band noise is limited to a specific frequency range and does not adequately represent the full spectrum of speech sounds. White noise contains all frequencies at equal intensity but lacks the specific spectral shape necessary to mimic speech characteristics effectively. Pure tone noise focuses on single frequencies and would not capture the complexity of speech sounds. Therefore, filtered broad band noise is the most appropriate choice for replicating the average spectrum of speech.