@inproceedings {Tolnai1543_2016,
	year = {2016},
	author = {Tolnai, Sandra and Beutelmann, Rainer and Lammers, Maike and Hillenbrand, Jacqueline and Klump, Georg Martin},
	title = {Behavioral Sensitivity to Interaural Level and Time Differences in the Mongolian Gerbil tested using Virtual Headphones},
	booktitle = {Assoc. Res. Otolaryng. MidWinter Meeting (ARO)},
	URL = {http://c.ymcdn.com/sites/www.aro.org/resource/resmgr/Abstract_Archives/UPDATED_2016_ARO_Abstract_Bo.pdf},
	abstract = {Gerbils’ sound localization ability has extensively been tested
under free-field stimulation (e.g., Heffner & Heffner, 1988;
Maier & Klump, 2006; Carney et al., 2011; Lingner et al.,
2012). While many neurophysiological studies use closedfield
or near-field stimulation to present signals with interaural
time and level differences (ITD and ILD, respectively), the
gerbil’s behavioral sensitivity to ITD and ILD has so far only
been derived from acoustic measurements (Maki & Furukawa,
2005) and free-field stimuli that favor the use of one or the
other interaural cue (Lesica et al., 2012). Here we investigate
the behavioral sensitivity of gerbils to ITD and ILD using freefield
loudspeakers to mimic stimulation via headphones.
Six Mongolian gerbils were trained in a left/right discrimination
task using broadband noise stimuli presented from a
loudspeaker array (-90° to +90°, minimum angle between
loudspeakers 12°). Data collection under the so-called virtualheadphone
stimulation started when animals reliably reached
>95% correct responses for the outermost loudspeaker
positions. Two loudspeakers in the array presented virtualheadphone
stimuli using cross-talk cancellation in order to
eliminate the undesired signal paths between the speakers
and their respective contralateral ears. The cross-talk
cancellation filters were based on head-related transfer
functions measured prior to the experiments from a gerbil
carcass.
Stimuli were narrow-band noise bursts (bandwidth: 200
Hz, centre frequency: 0.75, 1, 2, 4, or 6 kHz, 60 dB SPL)
to which either ITD (up to ±500 μs) or ILD (up to ±20 dB)
were applied. Psychometric functions were derived from the
animals’ responses and thresholds calculated at a sensitivity
level corresponding to a d’ of 1.
We found that all gerbils tested were able to lateralize sounds
depending on the applied ITD or ILD. For stimuli with an ILD,
reliable responses could be obtained for narrow-band noises
with center frequencies ≥2 kHz. For stimuli with an ITD,
reliable responses could be collected for center frequencies
up to 2 kHz. Responses to stimuli with an ITD were cyclic
indicating the use of phase information by the animals.
The data will be discussed in terms of its applicability by
comparing thresholds collected under virtual-headphone
stimulation with data from free-field stimulation.
Funding
This study was funded by the DFG (TRR 31 and Cluster of
Excellence “Hearing4all”).}
}