Dataset Information

Spatial hearing in echoic environments: the role of the envelope in owls.

ABSTRACT: In the precedence effect, sounds emanating directly from the source are localized preferentially over their reflections. Although most studies have focused on the delay between the onset of a sound and its echo, humans still experience the precedence effect when this onset delay is removed. We tested in barn owls the hypothesis that an ongoing delay, equivalent to the onset delay, is discernible from the envelope features of amplitude-modulated stimuli and may be sufficient to evoke this effect. With sound pairs having only envelope cues, owls localized direct sounds preferentially, and neurons in their auditory space-maps discharged more vigorously to them, but only if the sounds were amplitude modulated. Under conditions that yielded the precedence effect, acoustical features known to evoke neuronal discharges were more abundant in the envelopes of the direct sounds than of the echoes, suggesting that specialized neural mechanisms for echo suppression were unnecessary.

SUBMITTER: Nelson BS

PROVIDER: S-EPMC2930190 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Spatial hearing in echoic environments: the role of the envelope in owls.

Nelson Brian S BS Takahashi Terry T TT

Neuron 20100801 4

In the precedence effect, sounds emanating directly from the source are localized preferentially over their reflections. Although most studies have focused on the delay between the onset of a sound and its echo, humans still experience the precedence effect when this onset delay is removed. We tested in barn owls the hypothesis that an ongoing delay, equivalent to the onset delay, is discernible from the envelope features of amplitude-modulated stimuli and may be sufficient to evoke this effect. ...[more]

PMID: 20797540

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Project description:Sound localization is essential to perceive the surrounding world and to interact with objects. This ability can be learned across time, and multisensory and motor cues play a crucial role in the learning process. A recent study demonstrated that when training localization skills, reaching to the sound source to determine its position reduced localization errors faster and to a greater extent as compared to just naming sources' positions, despite the fact that in both tasks, participants received the same feedback about the correct position of sound sources in case of wrong response. However, it remains to establish which features have made reaching to sound more effective as compared to naming. In the present study, we introduced a further condition in which the hand is the effector providing the response, but without it reaching toward the space occupied by the target source: the pointing condition. We tested three groups of participants (naming, pointing, and reaching groups) each while performing a sound localization task in normal and altered listening situations (i.e. mild-moderate unilateral hearing loss) simulated through auditory virtual reality technology. The experiment comprised four blocks: during the first and the last block, participants were tested in normal listening condition, while during the second and the third in altered listening condition. We measured their performance, their subjective judgments (e.g. effort), and their head-related behavior (through kinematic tracking). First, people's performance decreased when exposed to asymmetrical mild-moderate hearing impairment, more specifically on the ipsilateral side and for the pointing group. Second, we documented that all groups decreased their localization errors across altered listening blocks, but the extent of this reduction was higher for reaching and pointing as compared to the naming group. Crucially, the reaching group leads to a greater error reduction for the side where the listening alteration was applied. Furthermore, we documented that, across blocks, reaching and pointing groups increased the implementation of head motor behavior during the task (i.e., they increased approaching head movements toward the space of the sound) more than naming. Third, while performance in the unaltered blocks (first and last) was comparable, only the reaching group continued to exhibit a head behavior similar to those developed during the altered blocks (second and third), corroborating the previous observed relationship between the reaching to sounds task and head movements. In conclusion, this study further demonstrated the effectiveness of reaching to sounds as compared to pointing and naming in the learning processes. This effect could be related both to the process of implementing goal-directed motor actions and to the role of reaching actions in fostering the implementation of head-related motor strategies.

Project description:ObjectivesSubjective questionnaires are informative in understanding the difficulties faced by patients with hearing loss. Our intent was to establish and validate a new questionnaire that encompasses situations emphasizing binaural hearing. The Spatial Hearing Questionnaire is a self-report assessment tool with eight subscales representing questions; pertaining to the perception of male, female, and children's voices; music in quiet; source localization; understanding speech in quiet; and understanding speech in noise.DesignThe Spatial Hearing Questionnaire, composed of 24 items, is scored from 0 to 100. It was administered to 142 subjects using one or two cochlear implants. Speech perception and localization abilities were measured, and the Speech, Spatial, and Other Qualities questionnaire was completed to evaluate validity of the questionnaire. Psychometric tests were performed to test the reliability and factor structure of the Spatial Hearing Questionnaire.ResultsResults showed high internal consistency reliability (Cronbach's alpha = 0.98) and good construct validity (correlations between the Spatial Hearing Questionnaire and other test measures, including the Speech, Spatial, and Other Qualities, were significant). A preliminary factor analysis revealed scores loaded on three factors, representing the following conditions: localization, speech in noise and music in quiet, and speech in quiet, explaining 64.9, 13.0, and 5.3% of the variance, respectively. Most of the questionnaire items (12/24) loaded onto the first factor that represents the subscale related to source localization. Mean scores on the Spatial Hearing Questionnaire were higher for subjects with bilateral cochlear implants than for subjects with a unilateral cochlear implant, consistent with other research and supporting construct validity.ConclusionsThe Spatial Hearing Questionnaire is a reliable and valid questionnaire that can be completed independently by most patients in about 10 minutes. It is likely to be a valuable tool for clinicians and researchers to measure spatial hearing abilities.

Dataset Information

Spatial hearing in echoic environments: the role of the envelope in owls.

Publications

Spatial hearing in echoic environments: the role of the envelope in owls.

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