Feb 12 (Reuters) - The U.S. hearing aid market grew 13 percent year-on-year in January, flattered by comparisons with 2014 when harsh winter weather depressed sales, data from Bernstein Research showed on Thursday.
North American sales generate 35 to 44 percent of revenues for the world's largest hearing aid makers including Switzerland's Sonova and Danish rivals GN Store Nord and William Demant.
Military veterans are a key customer in the United States, accounting for 22 percent of all hearing aid units sold there.
Sales to the Veteran Administration (VA), the largest U.S. healthcare organisation, showed the same unit-per-day growth of 14 percent as in previous month.
Sonova's share of the closely watched VA market recovered slightly to 41 percent in January. Sonova dominated with a 55 percent chunk as recently as 2013 but GN Store Nord has been gaining ground and had a 12 percent share in January.
William Demant kept its share of the VA market steady at nine percent in January.
GN Store Nord last week extended its supply agreement with retailer Costco. That was a relief for investors who saw William Demant shares drop after it cut its 2014 earning forecast because rivals had displaced its products from the U.S. group's stores. (Reporting By Alexander Tange; Editing by Keith Weir