Which probably provides a better explanation than anything I can conjure up at the moment. Though for clarity’s sake, I’ll write down my personal classifications of each frequency range:

20Hz to 80Hz: Sub-bass

Sub-bass 80Hz to 200Hz: Mid-bass

Mid-bass 200Hz to 800Hz: Lower midrange

Lower midrange 800Hz to 1,500Hz: Centre midrange

Centre midrange 1,500Hz to 5,000Hz: Upper midrange

Upper midrange 5,000Hz to 10,000Hz: Treble

Treble 10,000Hz+: Upper treble/”air”

Why is this distinction important? For starters, knowing what my definitions of each frequency range are helps to interpret reviews, especially for reviewers like me who often makes references to frequency response. Everyone has their own personal definitions and there are no strict set of rules that dictate where each frequency range ends and where another begins.

A different person might say that the term “upper mids” only refers to frequencies between 2kHz and 4kHz. Perhaps another would say that “upper bass” is a region that needs to be acknowledged and distinguished from the rest. Even the chart above disagrees with my classification and sees no need to specifically highlight “low mids” as its own frequency range, but that’s fine. As long as you’re aware of what I’m referring to whenever I use these terms, that’s the ultimate goal of using such descriptors.

You can make use of a FR graph to see whether or not your desired frequency range is boosted or dipped. Perhaps you’re a basshead, so a roll-off below 400Hz would be a huge red flag for you. The purpose of a FR graph is to allow you to objectively see the “signature” of a given headphone or IEM, and so is a vital (basically essential) part of your purchasing decisions as an audiophile, especially when you don’t have immediate physical access to said product.