Looking at the way the figures are expressed in the ads, sure, 24dB is better than 22dB. What's more, the 24dB set is cheaper
But I'd be amazed if anyone could tell the difference between 22dB and 24dB at the ear, and there could easily be +/-5dB variation due to head shape, etc. I suspect the difference in price is because the more expensive set has silicone, rather than foam, ear seals. I think most people find silicone more comfortable.