Here is the sentence:
As the emperor walked to the royal court, his heartbeat matched the booming of the drums through the fort.
I am not sure about the meaning of the word "matched" in the sentence above. Does the sentence mean "his heartbeat went up-down with the booming of the drums through the fort"?
The emperor is going to attend a celebration and he is very excited about this.
If you consult a dictionary, you'll see that one of the meanings of the verb to match is to be equal to something in quality or strength (it doesn't sound like it means to be in sync with something). So, we could say that the emperor's heartbeat was as strong as that of the booming of the drums or that his heartbeat matched the booming of the drums in strength (poetically speaking) because he was apparently very excited by what was going on as it, I would presume, was probably his coronation ceremony or something similar. I think all this description is just a figure of speech and should not be taken literally, of course.
Another way to write this sentence could be,
"As the emperor walked to the royal court, his heart beat in time with the booming of the drums through the fort."
The emperor's heart was beating at the same time at the drums were beating.
