The ‘wideband’ part of the name Wideband Absorbance (WBA) refers to the stimulus, which is a click i.e. a broadband sound. The ‘absorbance’ part of the name refers to how effectively the energy from a click sound is transmitted through the middle ear system. WBA is measured on a scale from 0 to 1, where 0 is no incident sound energy absorbed, and 1 is all incident sound energy absorbed. So, WBA is a measure of the effectiveness of the middle ear (to absorb sound) as a function of frequency. It has been shown that measuring middle ear function across frequencies (instead of just at a single frequency, or a handful of frequencies as in traditional tympanometry) can give clinicians a greater understanding of how certain disease processes affect the middle ear.
An overview of historical and recent developments in the field of wideband absorbance measurements can be found in the proceedings of the 2012 Eriksholm Workshop on Wideband Absorbance Measures of the Middle Ear, published in Ear and Hearing 2013, as a supplement to volume 34.
References and caveats
Lilly, D.J. and Margolis, R.H. (2013) Wideband acoustic immitance measurements of the middle ear: Introduction and some historical antecedents. Ear and Hearing, 34, Supplement 1, 4S – 8S.
For a brief description of absorbance please watch this video tutorial
For a more in-depth discussion please watch this webinar by Dr Lisa Hunter