Learn Dutch: Het irriteert hem, maar hij kan de geluiden verdragen. - It irritates him, but he can tolerate the noises.

No, in this sentence verdragen is just a regular verb meaning 'to tolerate'. It sits at the end of the sentence because it is paired with the modal verb kan (can). However, you could turn it into a noun phrase to fit this lesson's theme: het verdragen van de geluiden (the tolerating of the noises).

Why doesn't the word order change after maar?

Because maar (but) is a coordinating conjunction. Words like maar, en (and), and of (or) act like a bridge between two independent main clauses. They don't push the verb to the end or swap the subject and verb. The second clause just follows the standard subject-verb order: hij kan.

Is there a difference between geluiden and other words for noise?

Geluid is the general Dutch word for 'sound' or 'noise'. In the plural form geluiden, it simply means 'noises' or 'sounds'. If the noise is specifically a loud, bothersome racket, a Dutch speaker might use the word lawaai instead, which is an uncountable noun.

Could Het at the beginning of the sentence represent an infinitive noun?

Yes! While Het translates simply to 'It', in the context of this lesson it could refer back to an action acting as a neuter noun. For example, if someone was tapping their foot earlier in the story, Het tikken (The tapping) is a substantival infinitive, and the pronoun Het in this sentence would refer right back to that action.