I could see port noise being reduced, but I don't think it is correct to say a speaker with traditional port resonators is aperiodic just because it passes through some foam. Aperiodic speakers as traditionally described don't have ports.
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An aperiodic speaker is a sealed box with controlled leaks, which allows a sealed enclosure of smaller size than would otherwise be required. Normally, reducing the size of a sealed enclosure would create a peak in the FR and also in the impedance. The aperiodic vent reduces these peaks, at the expense of a steeper bass roll off than a sealed enclosure (normally 18db / octave). You don't see actual aperiodic loading in speakers very much.