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Abhijit Kulkarni is the first author, with H. Steven Colburn, of a 2000 study measuring variability in the headphone transfer function. Repeated placements on the KEMAR acoustical manikin changed the measured response, making it difficult to choose one inverse filter that reliably canceled the headphone contribution.^[ref]

The method supplies a clear example of measurement reproducibility. Repeating a measurement after removing and replacing the apparatus tests a different source of variation from repeating it without disturbing anything. The study identified the physical coupling of headphones to the ear region as part of the experimental system, rather than assuming an electronic input alone fixed the acoustic output.^[ref]

H. Steven Colburn is a researcher in auditory science and a coauthor with Abhijit Kulkarni of a 2000 study of headphone transfer function measurements. Using the KEMAR acoustical manikin, they repeatedly repositioned headphones and measured how their frequency response changed. This isolated placement variability while retaining the same experimental head and headphone system.^[ref]

A compensation filter based on one placement can become inaccurate after the cushion moves. The experiment therefore distinguishes a nominal device description from the sound actually delivered at the measurement point. That distinction matters when a hearing experiment depends on a precisely specified acoustic stimulus.^[ref]

M. D. Burkhard coauthored, with R. M. Sachs, a 1975 paper describing an anthropometric manikin for acoustics research. Such instruments provide a reproducible physical stand-in for measurements affected by the shape of a listener's head and torso.^[ref]

KEMAR provides the concrete apparatus example. Its documented configurations combine a head and torso with external-ear shapes, canal extensions and ear simulators for testing headphones and related equipment. The manufacturer describes these as approximations to human acoustic properties.^[ref]

A microphone alone measures the sound pressure at its position; placing it in a representative physical arrangement changes the experiment to include the effects of that arrangement. Repeatability of a manikin measurement does not imply that its response equals the response of every individual listener. Modern configurations also should not automatically be attributed to the original 1975 instrument.

R. M. Sachs coauthored, with M. D. Burkhard, a 1975 description of an anthropometric manikin for acoustics research. The contribution addressed a measurement problem: a test fixture should represent relevant features of a listener rather than merely hold a sensor in otherwise empty space.^[ref]

Current KEMAR documentation illustrates the approach with shaped head-and-torso fixtures and interchangeable ear-related components. These support controlled tests in which the apparatus configuration is recorded and reproduced.^[ref]

For a hypothetical comparison, use the same signal and fixture to test two headphone placements. A change in the measured response can then be investigated as a placement effect instead of being mixed with changes of listener anatomy. Conversely, changing an ear component changes the physical model itself. An interpretable comparison therefore specifies both the signal and the geometry.