I am revising a past review after working with Indow's customer service to handle a communications problem. I am ordering my second pair of inserts, and they work well for the areas promised. They effectively cut out high and mid-range frequencies. On the day I installed the inserts, there was a party across the street with approximately 20 loud children. The noise was completely blocked when I installed the inserts. I've also had a few times when I've been in my office and the neighbor's kids were playing in my yard; can't hear them at all. When I travel to visit my parents and get woken up by a dog barking somewhere in the neighborhood, or an HVAC machine kicking on, I think about the inserts because I'm positive they would block that sound. On low-range frequencies: the inserts aren't so great at blocking these. I was really hoping they would be, but not solidly expecting it. Low wavelengths are extremely difficult to block. I live by a noisy road with a steep hill. The high pitch swish of traffic gets blocked out, but low motor noises and engine sounds do not. I've found noise-cancelling headphones to be effective in this case. If you are buying these to block low pitched sounds, do your due diligence - you might not get much benefit from these (or much else, to be honest). But other sounds - dogs barking, the swish of a freeway half a mile away, etc - I think you'll be pleased. There was a communications issue on my last order, but it was promptly resolved.