What is headphone frequency response?

Understanding frequency response! How to describe the sound of

InnerFidelity Headphone Measurements Explained

Should I mix on headphones or speakers? - Blog

FiiO FT5 90mm Open Back Planar Magnetic Headphones – Apos Audio

What makes headphones with the same frequency range sound

How earphones should sound: Talking about target curves - USound

InnerFidelity Headphone Measurements Explained

About headphones measurements and frequency response in particular

How to eliminate nulls in headphone designs

How much does frequency response matter in earphones? - Quora

Raw Frequency Response

Who here likes a flat frequency response?