Time-intensity trade of bilaterally bone-conducted sounds in normal hearing subjects.
OBJECTIVE
In an effort to examine the rules by which information of bilaterally applied bone-conducted signals arising from interaural time differences (ITD) and interaural intensity differences (IID) is combined, data were measured for continuous 500 Hz narrow-band noise at 60 dBHL in 30 normal-hearing subjects using a centering method. Time-intensity trading functions were obtained by means of a sound image shifted towards one side by presenting an ITD, and shifted back to a centered sound image by varying the IID in the same ear. ITD values were varied from -600 to +600 microseconds at 200 microseconds steps, where negative values indicate delays to the right ear.


RESULTS
Time-intensity trading functions in response to bone-conducted signals showed significantly lower discrimination thresholds across IIDs, when compared to a control group with applied air-conducted signals. These findings can be interpreted as a constructive interference effect related to the intimate mechanism of bilateral bone conduction, where interaural time differences play a major role.


CONCLUSIONS
Time-intensity trade of bilaterally bone-conducted sounds in normal-hearing subjects is the highly sensitive. The high speed of sound through the skull may be the main reason for the high sensitivity of time-intensity trading.
Schmerber
S
S
University Hospital, Dept. of Otolaryngology, BP 217, F-38043, Grenoble, France. SSchmerber@chu-grenoble.fr
Sheykholeslami
K
K
Kermany
M H
MH
Hotta
S
S
Kaga
K
K
D000328:Adult; D002648:Child; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D012016:Reference Values; D012886:Skull; D013017:Sound Localization / Q000502:physiology*; D014732:Vibration