Real-ear measurement of hearing-aid interference from digital wireless telephones
Harry N. Levitt, Judy Harkins, Linda K. Kozma-Spytek, Eddy Yeung · The Journal of the Acoustical Society of America · 1999
Two studies were performed. The first measured hearing-aid interference under field conditions. Signal levels in the ear canal were measured using an in-the-canal probe system, the output of which was stored digitally in a laptop computer. Both bystander and user interference were measured as well as the user’s ratings of intelligibility, annoyance, and usability (of the digital wireless telephone). The levels of user-interference were found to be unacceptably high for the large majority of hearing-aid wearers. In contrast, bystander interference was at a relatively low level under conditions typical of telephone use. The second experiment controlled the level of interference by means of the test mode in the digital wireless telephone. Speech-to-interference ratios were measured in the ear canal for various levels of intelligibility and usability, as rated by the subjects. Data were obtained for 37 subjects on each of three digital wireless technologies (PC1900, TDMA, CDMA). [Research supported by NIDRR.]