The influence of hearing loss on directional hearing

Fifty patients with cochlear hearing loss were tested with phase audiometry. Thirty-three of the patients had unilateral hearing loss at 500 Hz and 17 bilateral, symmetrical hearing loss at 500 Hz. Those patients who had slight hearing loss (less than 40 dB HL) had as a rule normal directional hearing. Those who had hearing loss exceeding 40 dB HL at 500 Hz usually had abnormal directional hearing. The sound lateralization ability was independent of whether the hearing loss was unilateral or bilateral.

Age differences in response time to verbal and symbolic traffic signs

It is well established that verbal skills are maintained at a high level into old age while visuo-spatial skills begin to decline at an earlier age. it was hypothesized that the elderly would therefore respond more quickly to verbal traffic signs than to symbolic ones. In a test of this hypothesis, response times (RT's) to symbolic and verbal traffic signs were obtained from subjects in two age groups (19-29 and 65-77 years). While the elderly responded more slowly than the young subjects, they were an average of .2 seconds quicker in response to verbal traffic signs than symbolic ones. There were no differences in RT for symbolic and verbal signs for the young subjects. It is clear that the impact of traffic signs changes on the elderly deserves more attention than it is currently being given.

Neurological and neuropsychological deficiencies in a group of older adolescents with dyslexia

A group of 34 male adolescents with poor results on a spelling test and 34 controls were examined neurologically and neuropsychologically. The index group was inferior to the controls mainly in tasks involving fine motor control of the left hand, but also in auditory non-verbal sequential information processing and phoneme manipulation tasks. The manual sequencing disorder and the verbal and non-verbal auditory problems could be interpreted in terms of deficient information-processing in the left hemisphere, but the reason for the psychomotor disorder of co-ordination, mainly in the left hand, remains unclear.

Discrimination of the spatial distribution of concurrently active sound sources: some experiments with stereophonic arrays

Several experiments are described in which subjects were required to discriminate differences in the spatial distribution of concurrently active sound sources in stereophonic arrays. For pure tone stimuli and binaural listening, systematic discrimination functions were observed when relatively small intersource frequency differences (approximately 30 Hz) were present. For tonal stimuli, this discrimination task was reliably performed only for frequencies below 1500 Hz. Additional tests were conducted with amplitude-modulated tonal stimuli, low- and high-frequency uncorrelated noise, correlated low-frequency noise, and, with the uncorrelated low-frequency noise, for stimuli presented in both the vertical plane and under monaural listening conditions. The results of all of these manipulations support the notion that the spatial distribution of sources in a stereophonic array can be appreciated if disparate low-frequency energy is available from the sources in a horizontal configuration. The implications of these results are discussed relative to acoustic processing in the natural environment.

Temporal integration of tone glides by children with auditory-memory and reading problems

Temporal auditory integration for short-duration, frequency-varying signals was examined in children with deficits in auditory memory and reading. Signals were similar to those previously used: a fixed-frequency tone, a tone glide rising in frequency, and a tone glide falling in frequency. No significant differences were found between the Experimental and Control groups' thresholds as a function of signal class (i.e., fixed-frequency or tone glide) or duration. In addition, a significant asymmetry in the thresholds of short-duration rising and falling tone glides was found for both groups. Falling tone glides were detected at higher intensities than were rising tone glides. Data from this study indicated this particular group of children with auditory memory and reading problems was able to detect simple and complex short-duration signals in a manner similar to normal children.

Vestibular and auditory function in Usher's syndrome

Usher's syndrome is a recessive hereditary disorder in which a congenital hearing loss is combined with nyctalopia, retinal degeneration, and restriction of visual fields. The results of a comprehensive ophthalmic and neurotologic study on 70 patients are reported. Two distinct clinical and presumed genetic types were discernible on the basis of hearing impairment and vestibular sensitivity and, to a lesser extent, deterioration of retinal photoreceptor function. Such a classification has proved valuable in diagnosis, prognosis, and genetic counselling.

The precedence effect: revisited

The precedence effect, as investigated by Wallach et al. [Am. J. Psychol. 62, 324-336 (1949)] was studied in three experiments. Experiment I was a replication of the original work of Wallach et al. Although the first click pair appears to dominate the perception of the position of the lateral image, the effect of the first click pair does not appear to "offset" or "cancel" the effect of the second click pair in terms of producing a lateral image at midline. The data are consistent with Zurek's [J. Acoust. Soc. Am. 67, 952-964 (1980)] proposal that the binaural system is less sensitive to the interaural temporal difference of the second click pair. Experiment II indicated that the effect of the first click pair on lateral judgments still dominates that of the second click pair when the images are judged to be off midline. In all of these studies, the variability of the data is quite high. Experiment III showed that the first click pair also led to a larger change in masked thresholds (masking-level differences, MLDs) than does the second click pair. These data reconfirm the use of two-click stimuli for demonstrations of the precedence effect and they describe some of the limitations of the procedure and the generalities of the effect.

Late-onset auditory deprivation: effects of monaural versus binaural hearing aids

Performance on tests of pure-tone thresholds, speech-recognition thresholds, and speech-recognition scores for the two ears of each subject were evaluated in two groups of adults with bilateral hearing losses. One group was composed of individuals fitted with binaural hearing aids, and the other group included persons with monaural hearing aids. Performance prior to the use of hearing aids was compared to performance after 4-5 years of hearing aid use in order to determine whether the unaided ear would show effects of auditory deprivation. There were no differences over time for pure-tone thresholds or speech-recognition thresholds for both ears of both groups. Nevertheless, the results revealed that the speech-recognition difference scores of the binaurally fitted subjects remained stable over time whereas they increased for the monaurally fitted subjects. The findings reveal an auditory deprivation effect for the unfitted ears of the subjects with monaural hearing aids.

The adaptive-style theory of schizophrenic development: current research with schizophrenics

This paper first reviews the adaptive-style theory of schizophrenia that was published in 1973 along with the evidence gathered from normal male Ss. The theory emphasized the importance of perceived maternal behaviors in the development of maladaptive social and cognitive styles for the son. The problems of interpreting data gathered from normals in terms of their implications for schizophrenic development are considered in the present paper, as well as the rules of evidence adopted for post-1973 research with mental patients bearing upon the adaptive-style theory. Theory relevance and support has required that cognitive behaviors distinguishing normal males displaying the two adaptive styles also differentiate process and reactive schizophrenics in specified ways. In addition, these differences should represent sources of vulnerability to major psychotic symptoms. Five studies into delusions and auditory hallucinations are discussed in terms of how well they support adaptive-style theory.

[Specialized sensory perception in women with polycystic ovaries]

Specialized sensory perception was examined in 20 women with polycystic ovary syndrome and in 20 healthy women with normal ovulatory genital cycle. None of the healthy women disclosed any anomaly in sensory perception while with no exception all patients with polycystic ovary syndrome disclosed anomalies in sensory perception of one or other sensory analyzer. Defects in smell (hypoosmis) were more common (19 cases) than those of taste (hypogeusia) (II cases), of vestibular (14 cases) or auditory (3 cases) function, although defects in two or more analyzers occurred together in most of the cases. The association of the syndrome with anomalies in the sensory perception suggested that various central nervous structures beside these controlling the releasing factors are involved in the pathomechanism of the disease and that specialized sensory perception in man has much more to do with the neuroendocrine system than previously believed.

Development of sound production in normal, isolated, and deafened kittens during the first postnatal months

The development of calls (quantified by a series of acoustic parameters) of (a) normal, (b) socially isolated, and (c) deafened kittens that were released in four different situations has been studied from birth to 170 days of age. All call parameters studied except noise components show developmental changes that can be related to the development of (a) the vocal tract (fundamental frequency, harmonic with maximum intensity, upper-frequency limit and frequency range, occurrence of frequency, and intensity modulations), (b) feedback control through the auditory system (sound-pressure level, harmonic with maximum intensity, call-variability), and (c) motivational valuation of the releasing situations (duration). Isolated and deafened kittens displayed quantitative differences in certain call parameters compared with normal animals. Calls of deafened animals are, on the average, louder, more tonal and uniform, and differentially pitched compared with those of normal, hearing animals.

Auditory space representation in the superior colliculus of the big brown bat, Eptesicus fuscus

The auditory response areas of 123 superior collicular (SC) units of Eptesicus fuscus were studied under free-field acoustic stimulus conditions. A stimulus was delivered from a loudspeaker placed 14 cm in front of a bat. The best frequency of a unit was determined by changing the stimulus frequency until the minimum threshold was measured. A best frequency stimulus was then delivered as the loud-speaker was moved across the auditory space to determine the response center of the auditory response area of each unit. The response center was defined as the direction at which the unit had its lowest minimum threshold. The stimulus intensity was then raised 2-20 dB above the lowest minimum threshold of the unit and the response area for each stimulus intensity was determined. The response area of a unit expands with stimulus intensity, but the expansion is not even in all directions. The size of the response area of a unit does not correlate with its minimum threshold, best frequency, or recording depth. Response centers of 7 units were located directly in front of the animal, but most response centers were located in a limited portion of the contralateral auditory space. Although each unit has a response center which is the point of maximal sensitivity, the point-to-point representation of the auditory space is not systematically organized. We suggest that an animal with highly mobile external pinnae may not need an orderly auditory space map in its neural tissue for accurate sound localization.

Temporal lobe lesions and perception of species-specific vocalizations by macaques

Japanese macaques were trained to discriminate two forms of their coo vocalization before and after unilateral and bilateral ablation of the temporal cortex. Unilateral ablation of the left superior temporal gyrus, including auditory cortex, resulted in an initial impairment in the discrimination, but similar unilateral ablation of the right superior temporal gyrus had no effect. Bilateral temporal lesions including auditory cortex completely abolished the ability of the animals to discriminate their coos. Neither unilateral nor bilateral ablation of cortex dorsal to and sparing the auditory cortex had any effect on the discrimination. The perception of species-specific vocalizations by Japanese macaques seems to be mediated by the temporal cortex, with the left hemisphere playing a predominant role.

Eye position and visual attention influence perceived auditory direction

The singular and joint effects of eccentric visual fixation and peripheral visual attention upon the perceived auditory median plane (PAMP) of the head were examined in four subjects. They positioned a hidden, horizontally-moving sound source to the perceived median plane of the head, while fixating a light 20 degrees or 45 degrees to the right or left of the actual median plane, and attending to another light in peripheral vision. Analysis by multiple linear regression yielded a model for each subject which indicated the nature and weighting of those factors contributing to variance reduction in PAMP judgments. Three subjects showed a strong linear attention effect, resulting in shifts of the PAMP away from the locus of attention. Similarly, a strong linear fixation effect was discovered in two subjects, a weak effect in another, and a nonlinear, inverse fixation effect in the last. Additional factors were noted for some subjects. Possible explanations of the observed effects were discussed. The study indicates that both visual attention and visual fixation are critical factors in experiments on auditory space perception although inter-individual differences do exist in the nature and strength of the effects.