Here is one way to formulate this. You are an information processing machine with certain throughput. Article says 10 dB worth of energy going into your ear causes an average of 5% decrease in your throughput, in the form of processing cost to filter irrelevant bits out. What we don’t know is what that 10dB stimulus is representative of. 10dB of baby crying vs 10dB of equally distributed, unpatterned brown-noise vs 10dB of low frequency predator sounds are by definition are not going to get assigned the same attentional saliency and will have different processing costs. Furthermore, your individual processing machine will accrue certain biases throughout, so same stimulus will not have the same processing cost for everyone. A typical example would be combat PTSD biasing processing towards gunfire, so it would cost more to filter out fireworks later on. In sum, there is a lot of aggregation and averaging going on in this calculation and this is why %5 feels too little a cost for 10 dB.