A compelling study of over 2500 Border Collies which links merle and excess white colouring in this breed, to deafness. There is also some discussion of the piebald gene and deafness in other breeds.
http://www.lsu.edu/deafness/deaf.htm - Homepage of Dr George M. Strain – Deafness Expert. Includes references to current canine deafness research.
Glenn K et al. Determination of White Spotting in Dogs: An Investigation of Candidate Genes. Iowa State University Animal Industry Report 2007 A.S. Leaflet R2196.