General guidelines keep it at a comfortable level.

一般标准能够让你维持在舒适的听力程度。

Italy's debt could be capped, but could it ever be reduced to a more comfortable level?

意大利债务可控，但能否降至一个更合理的水平呢？

That way you will be able to hear the music at comfortable levels without having to turn it up to the highest level.

这样你就能在对耳朵友好的音量下听音乐，而不必调到最大声。