Laugesen, Søren, et al. “Variations in ‘adequate’ Own-Voice Level Used by Speakers and Preferred by Listeners When Communicating across a Distance”. Proceedings of the International Symposium on Auditory and Audiological Research, vol. 1, Dec. 2007, pp. 541-50, https://proceedings.isaar.eu/index.php/isaarproc/article/view/2007-54.