Detectability of Interaural Time Differences and Interaural Level Differences as a Function of Signal Duration

1972 ◽  
Vol 52 (2B) ◽  
pp. 574-576 ◽  
Author(s):  
Dennis McFadden ◽  
Alan D. Sharpley
Keyword(s):  
Signal Duration ◽  
Interaural Time Differences ◽  
Interaural Level Differences

scholarly journals Information conveyed by inferior colliculus neurons about stimuli with aligned and misaligned sound localization cues

2011 ◽  
Vol 106 (2) ◽  
pp. 974-985 ◽  
Author(s):  
Sean J. Slee ◽  
Eric D. Young
Keyword(s):  
Inferior Colliculus ◽  
Sound Localization ◽  
Virtual Space ◽  
Central Nucleus ◽  
Single Neurons ◽  
Interaural Time Differences ◽  
Marmoset Monkey ◽  
Interaural Level Differences ◽  
Broadband Sound ◽  
Response Area

Previous studies have demonstrated that single neurons in the central nucleus of the inferior colliculus (ICC) are sensitive to multiple sound localization cues. We investigated the hypothesis that ICC neurons are specialized to encode multiple sound localization cues that are aligned in space (as would naturally occur from a single broadband sound source). Sound localization cues including interaural time differences (ITDs), interaural level differences (ILDs), and spectral shapes (SSs) were measured in a marmoset monkey. Virtual space methods were used to generate stimuli with aligned and misaligned combinations of cues while recording in the ICC of the same monkey. Mutual information (MI) between spike rates and stimuli for aligned versus misaligned cues were compared. Neurons with best frequencies (BFs) less than ∼11 kHz mostly encoded information about a single sound localization cue, ITD or ILD depending on frequency, consistent with the dominance of ear acoustics by either ITD or ILD at those frequencies. Most neurons with BFs >11 kHz encoded information about multiple sound localization cues, usually ILD and SS, and were sensitive to their alignment. In some neurons MI between stimuli and spike responses was greater for aligned cues, while in others it was greater for misaligned cues. If SS cues were shifted to lower frequencies in the virtual space stimuli, a similar result was found for neurons with BFs <11 kHz, showing that the cue interaction reflects the spectra of the stimuli and not a specialization for representing SS cues. In general the results show that ICC neurons are sensitive to multiple localization cues if they are simultaneously present in the frequency response area of the neuron. However, the representation is diffuse in that there is not a specialization in the ICC for encoding aligned sound localization cues.

scholarly journals Crocodiles use both interaural level differences and interaural time differences to locate a sound source

2020 ◽  
Vol 148 (4) ◽  
pp. EL307-EL313
Author(s):  
L. Papet ◽  
M. Raymond ◽  
N. Boyer ◽  
N. Mathevon ◽  
N. Grimault
Keyword(s):  
Sound Source ◽  
Interaural Time Differences ◽  
Interaural Level Differences

scholarly journals Cues for Directional Hearing in the Fly Ormia ochracea

2021 ◽  
Vol 9 ◽  
Author(s):  
Andrew C. Mason
Keyword(s):  
Arrival Time ◽  
High Accuracy ◽  
Sound Stimulus ◽  
Directional Hearing ◽  
Neural Responses ◽  
Ormia Ochracea ◽  
Parasitoid Species ◽  
Interaural Time Differences ◽  
Internal Parasites ◽  
Interaural Level Differences

Insects are often small relative to the wavelengths of sounds they need to localize, which presents a fundamental biophysical problem. Understanding novel solutions to this limitation can provide insights for biomimetic technologies. Such an approach has been successful using the fly Ormia ochracea (Diptera: Tachinidae) as a model. O. ochracea is a parasitoid species whose larvae develop as internal parasites within crickets (Gryllidae). In nature, female flies find singing male crickets by phonotaxis, despite severe constraints on directional hearing due to their small size. A physical coupling between the two tympanal membranes allows the flies to obtain information about sound source direction with high accuracy because it generates interaural time-differences (ITD) and interaural level differences (ILD) in tympanal vibrations that are exaggerated relative to the small arrival-time difference at the two ears, that is the only cue available in the sound stimulus. In this study, I demonstrate that pure time-differences in the neural responses to sound stimuli are sufficient for auditory directionality in O. ochracea.

Spatial Stimulus Cue Information Supplying Auditory Saltation

Perception ◽  
10.1068/p3293 ◽  
2002 ◽  
Vol 31 (7) ◽  
pp. 875-885 ◽  
Author(s):  
Dennis P Phillips ◽  
Susan E Hall ◽  
Susan E Boehnke ◽  
Leanna E D Rutherford
Keyword(s):  
Spatial Perception ◽  
Interaural Time Difference ◽  
Free Field ◽  
Spatial Location ◽  
Interaural Level Difference ◽  
Sound Sources ◽  
Interaural Time Differences ◽  
Spatial Stimulus ◽  
Click Train ◽  
Interaural Level Differences

Auditory saltation is a misperception of the spatial location of repetitive, transient stimuli. It arises when clicks at one location are followed in perfect temporal cadence by identical clicks at a second location. This report describes two psychophysical experiments designed to examine the sensitivity of auditory saltation to different stimulus cues for auditory spatial perception. Experiment 1 was a dichotic study in which six different six-click train stimuli were used to generate the saltation effect. Clicks lateralised by using interaural time differences and clicks lateralised by using interaural level differences produced equivalent saltation effects, confirming an earlier finding. Switching the stimulus cue from an interaural time difference to an interaural level difference (or the reverse) in mid train was inconsequential to the saltation illusion. Experiment 2 was a free-field study in which subjects rated the illusory motion generated by clicks emitted from two sound sources symmetrically disposed around the interaural axis, ie on the same cone of confusion in the auditory hemifield opposite one ear. Stimuli in such positions produce spatial location judgments that are based more heavily on monaural spectral information than on binaural computations. The free-field stimuli produced robust saltation. The data from both experiments are consistent with the view that auditory saltation can emerge from spatial processing, irrespective of the stimulus cue information used to determine click laterality or location.

The role of alarm signal duration as a cue for alarm validity

2007 ◽  
Vol 38 (2) ◽  
pp. 191-199 ◽  
Author(s):  
James P. Bliss ◽  
Corey K. Fallon ◽  
Nicolae Nica
Keyword(s):  
Signal Duration ◽  
Alarm Signal

Single-Unit Responses in the Inferior Colliculus of Decerebrate Cats II. Sensitivity to Interaural Level Differences

1999 ◽  
Vol 82 (1) ◽  
pp. 164-175 ◽  
Author(s):  
Kevin A. Davis ◽  
Ramnarayan Ramachandran ◽  
Bradford J. May
Keyword(s):  
Frequency Response ◽  
Inferior Colliculus ◽  
Free Field ◽  
Central Nucleus ◽  
Type I ◽  
Discharge Rates ◽  
Ipsilateral Stimulation ◽  
Interaural Level Differences ◽  
Type V ◽  
Decerebrate Cats

Single units in the central nucleus of the inferior colliculus (ICC) of unanesthetized decerebrate cats can be grouped into three distinct types (V, I, and O) according to the patterns of excitation and inhibition revealed in contralateral frequency response maps. This study extends the description of these response types by assessing their ipsilateral and binaural response map properties. Here the nature of ipsilateral inputs is evaluated directly using frequency response maps and compared with results obtained from methods that rely on sensitivity to interaural level differences (ILDs). In general, there is a one-to-one correspondence between observed ipsilateral input characteristics and those inferred from ILD manipulations. Type V units receive ipsilateral excitation and show binaural facilitation (EE properties); type I and type O units receive ipsilateral inhibition and show binaural excitatory/inhibitory (EI) interactions. Analyses of binaural frequency response maps show that these ILD effects extend over the entire receptive field of ICC units. Thus the range of frequencies that elicits excitation from type V units is expanded with increasing levels of ipsilateral stimulation, whereas the excitatory bandwidth of type I and O units decreases under the same binaural conditions. For the majority of ICC units, application of bicuculline, an antagonist for GABAA-mediated inhibition, does not alter the basic effects of binaural stimulation; rather, it primarily increases spontaneous and maximum discharge rates. These results support our previous interpretations of the putative dominant inputs to ICC response types and have important implications for midbrain processing of competing free-field sounds that reach the listener with different directional signatures.

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