There will be natural variations in volume between readers. Reject only if the volume is so high that the recording breaks up, or (more commonly) if it is so low that you can’t hear what is being said without reference to the written text.
朗读者之间的声音大小会有自然差异。仅当音量太高以至于录音中断，或（更常见的情况）音量太小以至于不参考书面文字您就听不到正在说的内容时，才驳回。