Which of the following is listed as an unusual sound type?

• A. Yelling
• B. Footsteps
• C. Whispering
• D. Birds chirping

Answer: (A)

Unusual sound types are noises that stand out from everyday background noise and should trigger awareness. In many settings, footsteps and whispers are common, and birds chirping is a natural outdoor sound, so they don’t signal a problem. Yelling is loud and abrupt, often indicating distress, danger, or conflict, so it stands out as an unusual sound type that calls for quick attention or action. The other options fit typical, expected sounds rather than signals requiring heightened alertness. Thus, yelling is the unusual sound type.