Sound can become damaging to human hearing at levels above 85 decibels (dB), but among the options provided, 120 decibels is the most relevant threshold. Sounds at or above this level can cause immediate harm to hearing, leading to possible permanent hearing loss.
Here’s a quick overview of the given options:
- 1 decibel: This level is far too low to cause any damage.
- 50 decibels: This is a normal conversation level and is not damaging.
- 120 decibels: This is considered a level that can cause immediate hearing damage.
- 250 decibels: This level is beyond the threshold of hearing and is not a practical measure for sound levels.
Therefore, the answer is 120 decibels.