Interaural coherence for noise bands: Waveforms and envelopes

Aaronson, Neil L.; Hartmann, William M.

doi:10.1121/1.3290991

Cited by 9 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Baxter et al (2013) demonstrated that envelope shapes are involved in the simultaneous representation of multiple sound sources and thus provide the substrate for an envelope-dependent echo suppressing in barn owls (Nelson and Takahashi 2010). Recent studies also showed that the stimulus envelope and its ITD are theoretically less prone to reverberation and other decorrelating effects (Aaronson and Hartmann 2010). We speculate that, besides facilitating sound localization in echoic environments and the representation of multiple sound sources, the envelope is also beneficial for an unambiguous representation of the sound source position by providing phase-and frequencyindependent ITD information.…”

Section: Discussionmentioning

confidence: 99%

Envelope contributions to the representation of interaural time difference in the forebrain of barn owls

Tellers

Lehmann

Führ

et al. 2017

Journal of Neurophysiology

View full text Add to dashboard Cite

Birds and mammals use the interaural time difference (ITD) for azimuthal sound localization. While barn owls can use the ITD of the stimulus carrier frequency over nearly their entire hearing range, mammals have to utilize the ITD of the stimulus envelope to extend the upper frequency limit of ITD-based sound localization. ITD is computed and processed in a dedicated neural circuit that consists of two pathways. In the barn owl, ITD representation is more complex in the forebrain than in the midbrain pathway because of the combination of two inputs that represent different ITDs. We speculated that one of the two inputs includes an envelope contribution. To estimate the envelope contribution, we recorded ITD response functions for correlated and anticorrelated noise stimuli in the barn owl's auditory arcopallium. Our findings indicate that barn owls, like mammals, represent both carrier and envelope ITDs of overlapping frequency ranges, supporting the hypothesis that carrier and envelope ITD-based localization are complementary beyond a mere extension of the upper frequency limit. The results presented in this study show for the first time that the barn owl is able to extract and represent the interaural time difference (ITD) information conveyed by the envelope of a broadband acoustic signal. Like mammals, the barn owl extracts the ITD of the envelope and the carrier of a signal from the same frequency range. These results are of general interest, since they reinforce a trend found in neural signal processing across different species.

show abstract

Section: Discussionmentioning

confidence: 99%

Envelope contributions to the representation of interaural time difference in the forebrain of barn owls

Tellers

Lehmann

Führ

et al. 2017

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…In the time domain, the interaural correlation of the echo envelope changes with object width (Shackleton et al, 2005;Aaronson and Hartmann, 2010). Width-dependent correlation changes are shown in Figure 10B.…”

Section: Discussionmentioning

confidence: 99%

The Sonar Aperture and Its Neural Representation in Bats

Heinrich

Warmbold²,

Hoffmann

et al. 2011

J. Neurosci.

View full text Add to dashboard Cite

As opposed to visual imaging, biosonar imaging of spatial object properties represents a challenge for the auditory system because its sensory epithelium is not arranged along space axes. For echolocating bats, object width is encoded by the amplitude of its echo (echo intensity) but also by the naturally covarying spread of angles of incidence from which the echoes impinge on the bat's ears (sonar aperture). It is unclear whether bats use the echo intensity and/or the sonar aperture to estimate an object's width. We addressed this question in a combined psychophysical and electrophysiological approach. In three virtual-object playback experiments, bats of the species Phyllostomus discolor had to discriminate simple reflections of their own echolocation calls differing in echo intensity, sonar aperture, or both. Discrimination performance for objects with physically correct covariation of sonar aperture and echo intensity ("object width") did not differ from discrimination performances when only the sonar aperture was varied. Thus, the bats were able to detect changes in object width in the absence of intensity cues. The psychophysical results are reflected in the responses of a population of units in the auditory midbrain and cortex that responded strongest to echoes from objects with a specific sonar aperture, regardless of variations in echo intensity. Neurometric functions obtained from cortical units encoding the sonar aperture are sufficient to explain the behavioral performance of the bats. These current data show that the sonar aperture is a behaviorally relevant and reliably encoded cue for object size in bat sonar.

show abstract

“…We chose to quantify such disparity in terms of the interaural envelope coherence—the maximum value of the cross-correlation function from Eq. (16) for all lags (± τ ), |τ|≤ half a period of the modulation (Aaronson and Hartmann, 2010). To the extent that the auditory system works as a cross correlator of envelopes, this measure of similarity is appropriate.…”

Section: Measurements In Ear Canalsmentioning

confidence: 99%

On the localization of high-frequency, sinusoidally amplitude-modulated tones in free field

Macaulay

Rakerd

Andrews

et al. 2017

The Journal of the Acoustical Society of America

Self Cite

View full text Add to dashboard Cite

Previous headphone experiments have shown that listeners can lateralize high-frequency sine-wave amplitude-modulated (SAM) tones based on interaural time differences in the envelope. However, when SAM tones are presented to listeners in free field or in a room, diffraction by the head or reflections from room surfaces alter the modulation percentages and change the shapes of the envelopes, potentially degrading the envelope cue. Amplitude modulation is transformed into mixed modulation. This article presents a mathematical transformation between the six spectral parameters for a modulated tone and six mixed-modulation parameters for each ear. The transformation was used to characterize the stimuli in the ear canals of listeners in free-field localization experiments. The mixed modulation parameters were compared with the perceived changes in localization attributable to the modulation for five different listeners, who benefited from the modulation to different extents. It is concluded that individual differences in the response to added modulation were not systematically related to the physical modulation parameters themselves. Instead, they were likely caused by individual differences in processing of envelope interaural time differences.

show abstract

Interaural coherence for noise bands: Waveforms and envelopes

Cited by 9 publications

References 25 publications

Envelope contributions to the representation of interaural time difference in the forebrain of barn owls

Envelope contributions to the representation of interaural time difference in the forebrain of barn owls

The Sonar Aperture and Its Neural Representation in Bats

On the localization of high-frequency, sinusoidally amplitude-modulated tones in free field

Contact Info

Product

Resources

About