Adams, S., A. Dykstra, K. Abrams, J. Winnell, M. Jenkins, and M. Jog. “Conversational Speech Intensity under Different Noise Conditions in Hypophonia and parkinson’s Disease”. Canadian Acoustics, vol. 34, no. 3, Sept. 2006, pp. 96-97, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1839.