Which of the following is an example of intermittent noise?

The example of intermittent noise is correctly identified as the hammer hitting a nail. Intermittent noise is characterized by sounds that occur in bursts or intervals rather than constantly.

In this context, the hammer striking a nail produces brief, sharp sounds that can be heard at irregular intervals during the construction process. This aligns well with the definition of intermittent noise, where the noise level fluctuates and is not constant over time.

Other sounds, such as engine noise or continuous humming, represent more consistent, ongoing sounds – making them examples of continuous noise rather than intermittent. Meanwhile, a gunshot, while sudden and loud, is typically classified as a single impulse of noise rather than a repeated intermittent sound, as it doesn't occur in a sequence of distinct, recurring bursts. Thus, the hammer hitting a nail is a clear example of intermittent noise due to its brief and sporadic nature.