Effects of noise bands on contralateral pure tone adaptation

The purpose of this study was to investigate the changes in threshold tone decay which result from contralaterally presented stimuli at an intensity less than interaural crossover. Five tone decay tests were administered at both 1,000 Hz and 2,000 Hz to 25 normal hearing adults. At each test frequency five contralateral conditions (no competing noise, white noise, narrow band noise centered at the test frequency, narrow band noise centered below the test frequency, and narrow band noise centered above the test frequency), were presented at 40 db above detection threshold to the nontest ear. Results showed a significant shift in tone decay scores when the conditions of white noise and narrow band noise centered around the test frequency were compared to the condition of no competing noise. A shift was seen at both frequencies but that occuring at 2,000 Hz was significantly greater than the shift at 1,000 Hz. No significant increase in tone decay was found for contralateral noise bands above or below the test frequencies.