The thresholds of the low frequencies increased by 1.0 decibel in the folic acid group and by 1.7 decibels in the placebo group, the researchers said.

• 研究者表示，叶酸组低频声音损伤的阈值提高了1.；0分贝，而安慰剂对照组低频声音损伤的阈值提高了1