In a deserted alley, a detective hears a voice echoing his own words. But there’s no one around. What is the source of this eerie sound?

Category: Mystery · Difficulty: hard

Hint: Think about technology that can mimic sounds.

Answer

A hidden speaker

Explanation

The hidden speaker could be used to create an unsettling atmosphere, suggesting someone is manipulating the environment.

This is a hard mystery riddle — a tricky one that takes a little thought. The answer is A hidden speaker.

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