What type of noise is ineffective for speech testing?

Narrow band noise is considered ineffective for speech testing because it does not adequately mask or interfere with the particular frequencies that are crucial for understanding speech. Speech sounds primarily occupy a specific frequency range, and the use of narrow band noise can potentially mask only a small segment of that frequency range. This means that important speech cues may still be audible, making it difficult to assess a person's speech understanding accurately.

In contrast, other types of noise, such as white noise, are more effective for speech testing. White noise provides a wide spectrum of sound frequencies, which can cover the frequencies of speech more comprehensively. Broadband noise similarly encompasses a broader range of frequencies, making it suitable for masking various speech sounds effectively.

By utilizing a noise type that covers a wider frequency spectrum, audiologists can create a more challenging listening environment that allows for a more accurate evaluation of a person's speech comprehension. Hence, narrow band noise falls short in this regard, making it the least effective option for speech testing.