Purpose
Most of HTL's measurements generate graphical results but there are some single-figure outcomes, either because the measurement generates a single figure or because a figure is derived or extracted from a dataset. The results table is where these single-figure results are gathered together.
Method
Headphone voltage sensitivity (SPL for 1 volt rms input at 1kHz, averaged over the two capsules) is calculated from the measurements of uncorrected frequency response. Power sensitivity (SPL for 1 milliwatt at 1kHz) and current sensitivity (SPL for 10 milliamps at 1kHz) are calculated from this figure with reference to the headphone's measured impedance at 1kHz. Maximum and minimum impedance values, and the frequencies at which they occur, are extracted from the left capsule impedance measurement, and bass extension (for -6dB reference the output at 200Hz) is extracted, separately for each capsule, from the mean uncorrected frequency resonses. Headphone weight is measured using precision electronic scales, and the headphone's head clamping force determined using a purpose-built test stand that incorporates a load cell. (More detail about this hardware can be found here.) Stability factor - intended to estimate how stable the headphone is on the head if its wearer is exercising - is calculated by dividing the head clamping force (in newtons) by the headphone weight (in kilograms).