Leaks from hair, glasses, and jaw contours cause bass loss test fixtures miss

Evidence

The anatomical variability in human heads and ears means that there can be significant variability in measurements of headphones made on humans. The stiffness of the pinna and how easily it can be formed or flattened by the headphone cushion can affect how well it seals. When the cups are large and easily fit around the pinna the shape and contour of the cheek and jaw can affect the seal and cause a leak. Hair and glasses can also introduce leaks. What the listener hears (a lack of bass) may not be reflected in the test fixture measurement, and the correlations between the two become weaker. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1718