Binaural horizontal plane localization: Spectral cues as a factor

AbstractChronic single-sided deaf (CSSD) listeners lack the availability of binaural difference cues to localize sounds in the horizontal plane. Hence, for directional hearing they have to rely on different types of monaural cues: loudness perceived in their hearing ear, which is affected in a systematic way by the acoustic head shadow, on spectral cues provided by the low-pass filtering characteristic of the head, and on high-frequency spectral-shape cues from the pinna of their hearing ear. Presumably, these cues are differentially weighted against prior assumptions on the properties of sound sources in the environment. The rules guiding this weighting process are not well understood. In this preliminary study, we trained three CSSD listeners to localize a fixed intensity, high-pass filtered sound source at ten locations in the horizontal plane with visual feedback. After training, we compared their localization performance to sounds with different intensities, presented in the two-dimensional frontal hemifield to their pre-training results. We show that the training had rapidly readjusted the contributions of monaural cues and internal priors, which resulted to be imposed by the multisensory information provided during the training. We compare the results with the strategies found for the acute monaural hearing condition of normal-hearing listeners, described in an earlier study [1].

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Spectral cues provided by the pinna for monaural localization in the horizontal plane

Perception & Psychophysics ◽

10.3758/bf03207357 ◽

1981 ◽

Vol 29 (5) ◽

pp. 438-444 ◽

Cited By ~ 25

Author(s):

Rosemary Flannery ◽

Robert A. Butler

Keyword(s):

Horizontal Plane ◽

Spectral Cues

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Spectral cues which influence monaural Localization in the horizontal plane

Perception & Psychophysics ◽

10.3758/bf03199700 ◽

1977 ◽

Vol 22 (4) ◽

pp. 353-358 ◽

Cited By ~ 11

Author(s):

Krystyna Belendiuk ◽

Robert A. Butler

Keyword(s):

Horizontal Plane ◽

Spectral Cues

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Effects of Altering Spectral Cues in Infancy on Horizontal and Vertical Sound Localization by Adult Ferrets

Journal of Neurophysiology ◽

10.1152/jn.1999.82.5.2294 ◽

1999 ◽

Vol 82 (5) ◽

pp. 2294-2309 ◽

Cited By ~ 42

Author(s):

Carl H. Parsons ◽

Richard G. Lanyon ◽

Jan W. H. Schnupp ◽

Andrew J. King

Keyword(s):

Sound Localization ◽

Horizontal Plane ◽

Broadband Noise ◽

Neural Representation ◽

Localization Task ◽

Midsagittal Plane ◽

Relative Localization ◽

Spectral Cues ◽

Spectral Localization ◽

Localization Ability

We investigated the behavioral consequences of removing the pinna and concha of the external ear bilaterally in infancy on the sound localization ability of adult ferrets. Altering spectral cues in this manner has previously been shown to disrupt the development of the neural representation of auditory space in the superior colliculus. Using broadband noise stimuli, we tested pinnae-removed ferrets and normal ferrets in three sound localization tasks. In each case, we found that both groups of animals performed significantly better when longer duration noise bursts were used. In a relative localization task, we measured the acuity with which the ferrets could discriminate between two speakers in the horizontal plane. The speakers were placed symmetrically either around the anterior midline or around a position 45° lateral to the midline. In this task, the pinnae-removed ferrets achieved very similar scores to the normal ferrets. By contrast, in another relative localization task that measured localization ability in the midsagittal plane, pinnae-removed ferrets performed less well than normals. In an absolute localization task, 12 speakers were spaced at 30° intervals in the horizontal plane at the level of the ferrets' ears. Overall, the pinnae-removed ferrets also performed poorly in this task compared with normal ferrets: they made significantly fewer correct responses, larger localization errors and more front-back errors. Both normal and pinnae-removed animals showed an improvement in performance with practice, although the pattern of improvement differed for each group. The largest improvements in localization accuracy were achieved by the pinnae-removed ferrets, particularly at the frontal positions, and their performance eventually approached that of the normal animals. Nevertheless, some intergroup differences were still present. In particular, the pinnae-removed ferrets continued to make significantly more front-back errors than the normals. These deficits can be attributed to differences in the spectral localization cues available to the animals. Acoustical measurements showed that, compared with normal animals, the head-related transfer functions in the horizontal plane were largely ambiguous around the interaural axis and also contained fewer location-dependent features in the midsagittal plane.

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Effect of Consonant-Vowel Ratio Modification on Amplitude Envelope Cues for Consonant Recognition

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3402.415 ◽

1991 ◽

Vol 34 (2) ◽

pp. 415-426 ◽

Cited By ~ 16

Author(s):

Richard L. Freyman ◽

G. Patrick Nerbonne ◽

Heather A. Cote

Keyword(s):

White Noise ◽

Intensity Ratio ◽

Recognition Performance ◽

Amplitude Envelope ◽

Signal To Noise ◽

Noise Masking ◽

Spectral Cues ◽

Consonant Recognition ◽

Nonlinear Amplification ◽

Speech Envelope

This investigation examined the degree to which modification of the consonant-vowel (C-V) intensity ratio affected consonant recognition under conditions in which listeners were forced to rely more heavily on waveform envelope cues than on spectral cues. The stimuli were 22 vowel-consonant-vowel utterances, which had been mixed at six different signal-to-noise ratios with white noise that had been modulated by the speech waveform envelope. The resulting waveforms preserved the gross speech envelope shape, but spectral cues were limited by the white-noise masking. In a second stimulus set, the consonant portion of each utterance was amplified by 10 dB. Sixteen subjects with normal hearing listened to the unmodified stimuli, and 16 listened to the amplified-consonant stimuli. Recognition performance was reduced in the amplified-consonant condition for some consonants, presumably because waveform envelope cues had been distorted. However, for other consonants, especially the voiced stops, consonant amplification improved recognition. Patterns of errors were altered for several consonant groups, including some that showed only small changes in recognition scores. The results indicate that when spectral cues are compromised, nonlinear amplification can alter waveform envelope cues for consonant recognition.

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