Judging from his tone, there's no doubt he is against it.

听他的话音，便知他是反对的。

《新英汉大辞典》

From his tone I judged he was annoyed with someone.

从他的腔调，我估计他是在生谁的气。

youdao

All that Silver said was a riddle to him, but you would never have guessed it from his tone.

西尔弗所说的这一切，对他来说是一个谜，但是你从他的口气中却决不会察觉出来。

youdao

The Rhode Island senator said he is disappointed Jeffords' defection did not change the partisan tone from his party leaders.

CNN: Chafee might depart GOP if party retakes Senate

But his tone from the podium was rather different.

BBC: State of the Union: Obama pledges to reignite economy

The WSJ article did not quote any sources by name, but the tone implied that the author got his information from some Fed policymaker.

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