释义：

speak up 大声说，表达意见

表示再大声点（up）说话，在说话或打电话时如果听不清对方的话就可以用这个短语。当然，在表达自己的意见时可以用。另外，speak out 还具有大声说话或呐喊的意思。

例句：

Could you speak up, please?
你能大声点吗？
I can't hear you. You'll have to speak up.
我听不清，请大声说话。
If you're going to say something; you're going to have to speak up.
如果你想说些什么，就一定大声说出来。

对话：

A: Mr. Smith, is this your wallet?
史密斯先生，这是你的钱包吗？
B: Speak up. I can't hear what you said
大声点，我听不清你的声音。