Bruce, I. C., S. U. Ansari, H. S. Bajaj, and K. Mustafa. “Multiband Compression and Contrast-Enhancing Frequency Shaping in Hearing Aids”. Canadian Acoustics, vol. 32, no. 3, Sept. 2004, pp. 62-63, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1628.