ものおと物音monooto
1.

A sound that is produced by an object or event, often emphasizing the impression of being unintended or unexpected.

2.

A noise that is not easily identifiable, typically arising from natural sources like wind or waves, but distinct from specific, recognizable sounds.

3.

An audible expression of a disturbance or interruption in one's environment, implying a lack of clarity about its origin.

Example:

少年は物音に震えた。