For those who prefer to look at the research directly, the best place to start is the recent literature review funded by a grant from hyperacusisresearch.org and Hearing Health Foundation. Dr. Richard Tyler of the University of Iowa led the review with contributions from researchers throughout the country.
A Review of Hyperacusis and Future Directions: Part 1 Definitions and Manifestations
A Review of Hyperacusis and Future Directions: Part 2 Measurement, Mechanisms, and Treatment
The papers can be found in the recent news page of hyperacusis.net under the December 2014 heading.