Abstract: Auditory and visual space are mapped in the optic tectum of the barn owl. Normally, these maps of space are in close mutual alignment. Ear plugs inserted unilaterally in young barn owls disrupted the binaural cues that constitute the basis of the auditory map. Yet when recordings were made from the tecta of these birds as adults, the auditory and visual maps were in register. When the ear plugs were removed from these adult birds and binaural balance was restored, the auditory maps were shifted substantially relative to the visual maps and relative to the physical borders of the tecta. These results demonstrate that the neural connectivity that gives rise to the auditory map of space in the optic tectum can be modified by experience in such a way that spatial alignment between sensory modalities is maintained.

Abstract: A single neural model is proposed to account for how responses of the two eyes and two ears combine to form the perception of binocular brightness and binaural loudness respectively. It involves nonlinear reciprocal feedback inhibition between left and right channels, followed by linear summation between the channels. Local circuit synaptic interactions are an important source of nonlinearity. The model combines inputs in a manner that approximates vector magnitude models in general. This suggests that the model can be applied to a variety of circumstances beyond the visual and auditory data discussed here.

Abstract: The hypothesis that the Repetition Task partially reflects the listener's level of perceptual learning was tested in this study. Specifically, it was predicted from data on auditory temporal proces...

Abstract: The control of oscillatory eye movements in congenital nystagmus was studied in five human subjects. Auditory feedback of eye position and eye motion was given to each subject to aid in controlling the abnormal eye movement. Less than one hour was needed for all the subjects to learn to use the auditory information. Reductions in eye movement amplitude ranged from 41 to 73%. Sensory functions like visual acuity and contrast sensitivity also improved under the auditory feedback condition. Auditory feedback of eye position is thought to have potential usefulness in the treatment of congenital nystagmus.

Abstract: Auditory processing deficits and articulation disorders were studied in a group of male juvenile delinquents. Significant auditory processing deficits were frequently observed and were significantl...

Abstract: 'Sagar HJ, Warlow CP, Sheldon PWE, Esiri MM. Multiple sclerosis with clinical and radiological features of cerebral tumour. J Neurol Neurosurg Psychiatry 1982;45:802-8. 2 Matthews WB. Multiple sclerosis. In: Recent Advances in Clinical Neurology, vol. 2, Matthews WB, Glaser GH eds. Edinburgh, Churchill Livingston 1978. 3 Van der Velden M, Bots GTAM, Endtz U. Cranial CT in multiple sclerosis showing a mass effect. Surg Neurol 1979;12:307-10.

Abstract: The House-Urban single-channel cochlear implant (CI) was first implanted in a patient in 1972 after an extensive investigation of multiple-electrode hardwired systems in three patients. The major goal in the design of the singlechannel, single-electrode system was to provide a prosthesis that was safe, had a high degree of clinical efficacy, and was biologically stable. To begin, we should consider the rationale that forms the basis for the engineering decisions which resulted in the present House-Urban CI. There are three key components of the House-Urban CI device that will be briefly reviewed: (1) bandpass filtering of the input speech spectrum; (2) amplitude modulation of a 16-kHz carrier wave; and (3) transmission of the AM signal to the implanted electrodes via a magnetic induction coil system. The design of the input filter section is based on data collected from patients using speech and environmental sound tests, as well as subjective evaluations under everyday listening conditions. The 3-dB downpoints for the lowand high-frequency cutoffs of the filter are 200 and 4000 Hz, respectively. Our experience has demonstrated that lowering the low-frequency cutoff results in interference and annoyance due to environmental sound with no improvement in speech discrimination or environmental sound recognition. Increasing the high-frequency cutoff above 4 kHz also does not improve performance with this CI system. The amplitude-modulated high-frequency carrier system was originally selected because (1) it was believed that there would be negligible net DC; (2) it allowed efficient energy transfer across the skin via the induction coils; and ( 3 ) it allowed frequency coding over the entire speech spectrum with little effect from the induction coil transfer characteristics. The decision to use a 16-kHz carrier signal was based primarily on threshold considerations and patient preference. A magnetic induction system was designed for transmitting signals from the processor to the implanted electrodes since it was believed that to be useful as a long-term clinical device, that is, to avoid tissue reaction and rejection, the connection should not protrude through the skin. It was also felt that by keeping the implanted device as simple as possible, with a minimum of implanted electronic components, the chance of internal device failure would be substantially reduced. From the standpoint of safety and clinical efficacy these bioengineering decisions have stood the test of time.

Abstract: : When a person listens to speech corrupted by noise or other adverse environmental factors, speech intelligibility may be impaired slightly or not at all. The same corrupted speech, after being vocoded, often causes drastic intelligibility loss. The is due to the fact that the human peripheral auditory system is a superior signal processor to that of the vocoder. This report is based on the premise that a vocoder analyzer that better resembles the peripheral auditory system would function in a superior manner to present-day vocoders. Topics include reviews of speech enhancement techniques, perceptual analysis of diagnostic rhyme test data, a brief description of the peripheral auditory system and an outline of proposed psychophysical tests. The final section is devoted to a discussion of some preliminary work on computer simulation of an auditory model.

Abstract: The receptive field is a functional descriptor of sensory neurons. It is that part of the sensory environment to which a neuron reponds. The receptive field (RF) of an auditory neuron describes the form and structure of its neuro-acoustic space; the coherent integration of all neuro-acoustic spaces represents the characteristics of the bio-acoustic space of the animal. Potential dimensions of the receptive field may, hypothetically at least, be derived from behavioral studies for the sensory system under consideration. Auditory perception is directed toward localization and identification of acoustic sources. As a consequence, incorporating at the same time arguments from neurophysiological experiments, receptive fields of auditory neurons can be considered as spatio-spectro-temporal configurations in acoustic space. The spatio-temporal aspects form the basis for determination of position and movement, while the spectro-temporal aspects contribute to the identification of acoustic sources.

Abstract: Subjects synchronized their taps with each isochronous pulse train in a polyrhythmic superposition of two conflicting pulse trains (the 2 by 3 and the 3 by 4). Perception of each isochronous pulse train depends on the presentation rates. At fast presentation rates, each pulse train could be perceived as a separate stream, organized by the frequency similarity principle. At slow presentation rates, the perception of a pulse train interferes with the other pulse train; it depends on other factors such as interval duration, frequency, and position of the elements in the polyrhythmic structure. These data are consonant with the phenomenon of "steam segregation."

Abstract: Twenty four adult patients who presented to a number of hospital services with complaints generally related to difficulty hearing, understanding, remembering, or writing were examined for auditory perceptual disorders All subjects exhibited neurological functioning, auditory acuity, and language abilities within normal limits On examination, all patients exhibited disorders in a number of areas of auditory perception The results of this study support the desirability of examining auditory perceptual abilities in adults of all ages even though the tools available are designed primarily for children The most important benefit from diagnosing the presence of auditory perceptual problems in adults is the opportunity to improve the quality of their life by assisting them to function more effectively in their current home or work environment

Abstract: Housemice have a vocal repertoire of 8 different call types, at least 4 of these are used in intraspecific communication (Ehret, 1975; Haack et al., 1982; Whitney and Nyby, 1982). There is always interindividual variability among calls of one type; therefore, the receiver of the calls must generalize across this variability in order to identify a call type, and to discriminate a particular call from others and from the acoustic background. The present paper deals with ultrasound perception by house mice. This example of call perception clearly demonstrates the abilities of the animals to generalize, to identify and to discriminate species-specific calls. The key-stimulus configuration in the frequency domain for ultrasound perception is described and then the physiological basis for why and how the mouse is able to perceive the ultrasonic calls is discussed.

Abstract: Most research in auditory implants is directed toward unaided speech comprehension for the profoundly deaf. Guided by past studies, the seemingly infinite number of possible electrical stimulation patterns for representing speech can be lessened, possibly resulting in spcech-coding strategies that attain this goal. We hope to aid this convergence with this summary of the relative effectiveness of some speech-coding schemes we have appraised. Since the summer of 1977, the Stanford Auditory Prosthesis Project has been evaluating the auditory perceptions of two subjects having four-wire modiolar electrode implants. The wire electrode array is connected to a fiveterminal transcutaneous plug behind the implanted ear. Currently, only one volunteer subject, R.F., is undergoing testing; the other subject, J.M., underwent explantation in 1979 because of infection. R.F., who lives close to Stanford University, has been readily available for testing for the past 5 years. This testing has spanned the range from basic psychoacoustical studies to studies of performance with various speech-coding algorithms. These speech-coding schemes are the focus of this paper: we will present a summary of the rationale behind the coding schemes and data about the subjects’ relative performance on them, and then we will conjecture on the reasons for the observed differences in relative performance.

Abstract: This study presents a psychoacoustic analysis of the integration of spectral and temporal cues in the discrimination of simple nonspeech sounds. The experimental task was a same-different discrimination between a standard and a comparison pair of tones. Each pair consists of two 80-ms, 1500-Hz tone bursts separated by a 60-ms interval. The just-discriminable (d' = 2.0) increment in duration delta t, of one of the bursts was measured as a function of increments in the frequency delta f, of the other burst. A trade off between the values of delta t and delta f required to perform at d' = 2.0 was observed, which suggests that listeners integrate the evidence from the two dimensions. Integration occurred with both sub- and supra-threshold values of delta t or delta f, regardless of the order in which the cues were presented. The performance associated to the integration of cues was found to be determined by the discriminability of delta t plus that of delta f, and thus, it is within the psychophysical limits of auditory processing. To a first approximation the results agreed with the prediction of orthogonal vector summation of evidence stemming from signal detection theory. It is proposed that the ability to integrate spectral and temporal cues is in the repertoire of auditory processing capabilities. This integration does not appear to depend on perceiving sounds as members of phonetic classes.

Abstract: Auditory perceptual functioning, specifically auditory memory and discrimination, has been historically considered related to linguistic development, in particular phonological development. This fact has resulted in therapy for children with delayed/deviant phonological development being focused on improving auditory memory and discrimination. A number of studies have been carried out over the past few decades to establish whether or not this relationship exists. These studies are reviewed and reasons for the diversity of results discussed. The phonological development of 60 children in relation to their auditory memory and discrimination is described, together with a test of auditory discrimination designed for the purposes of the study.

Abstract: Two experiments were undertaken to examine the performance of language-impaired children on auditory identification and sequencing tasks which employed different stimuli. The purpose of Experiment I was to determine if introduction of linguistic stimuli (words) into tasks using nonlinguistic stimuli (complex tones) would change subjects' performance. Experiment II was designed to measure differences in response when words and tones were presented separately. Responses to utterances of increasing length (up to four words) were also measured. Results indicated that some children performed significantly better when words were used as stimuli. No child responded better when tones were used as stimuli and there were no significant differences between utterances of different length. Based on these results and on the related literature, considerations for choice of stimuli for intervention with language-impaired children are discussed.

Abstract: Auditory induction is the apparent continuation of a fainter sound when alternated rapidly with a more intense interrupting sound. In the present study, induction of discrete (nonalter­ nating) tones by "contextual" tones was examined in three experiments using signal detection methods. Listeners were asked to detect pure tone signals of constant, rising, or falling fre­ quency embedded in noise bursts. The noise bursts were preceded and followed by contextual tones that were designed to produce a constant or changing frequency context. The results of the first two experiments showed that detection of "in-context" signals (e.g., a rising-frequency signal in a rising-frequency context) was associated with an increased false-alarm rate and lowered sensitivity, as compared with "out-of-context" signals (e.g., a falling-frequency signal in a rising-frequency context], To examine the possible influence of peripheral masking, a third experiment was conducted in which signals and contextual tones were presented to different ears. The same pattern of selective contextual impairment of detection performance was ob­ tained. The results indicated that auditory induction can occur with discrete presentation of tones: the contextual tones are perceived as continuing through the noise bursts, and this illu­ sion degrades detection performance. However, the effect occurs only when a signal to be de­ tected is consistent with its context. The results suggest that auditory induction and peripheral masking are independent processes that can cumulatively degrade detection performance with nonspeech sounds. Perception of speech and of other environmental sounds can reflect the influence of either bottom-up (sensory) or top-down (cognitive) factors. Bottom-up factors, such as the acoustic waveform and peripheral auditory mechanisms, determine the initial input, and top-down factors related to a listener's skills, in­ tentions, and knowledge act upon this input to con­ struct a perceptual representation. Since auditory perception usually reflects the joint or interactive in­ fluence of both bottom-up and top-down factors (e.g., Samuel, 1981a), a strict division of factors that

Abstract: Dr Prince confuses three separate issues in his comments on our paper about intracellular recordings from human and monkey “epileptic” cortex [4]. The first question is whether the in vitro slice preparation is adequate for investigating the cellular mechanisms underlying epileptogenesis. My colleagues and I believe that this in vitro approach has considerable potential, and we continue to carry out such studies; indeed, we have collected interesting new data which will be reported soon. The second question is whether current results from in vitro studies of human tissue provide convincing data on differences between epileptic and normal cortex. Conservative interpretation of available intracellular data does not allow one to identify cortical slices as “epileptic” or “normal.” In our paper [4], we clearly indicated that controls were inadequate, and we therefore made no claim as to the epileptogenicity of any given tissue sample. The point is not that our controls were better than those of Prince and Wong 12) but rather that neither study had adequate controls. From this perspective, therefore, the Prince and Wong interpretation was premature. Since there is evidence that much of cortex may be abnormal in epileptic brain 111, why should one assume that cortex in brain with other abnormalities but without electrocorticographical spikes (i.e., the Prince and Wong “control” cortex) is normal? And what are the normative data that allow a comparison of epileptic temporal cortex and normal frontal or parietal cortex? While I was at Stanford, I personally carried out some of the electrophysiological human slice studies subsequently reported by Prince and Wong 121. O n the basis of those four or five experiments, no distinction could be made between epileptic and normal cortex. It is, of course, possible that additional studies and sophisticated data analysis could reveal trends and differences not obvious from these initial experiments, but the specific analyses that led to Prince and Wong’s more “optimistic” interpretations were not explained [2). We do not maintain that differences do not exist between tissue slices from epileptic and normal brain; rather, we maintain that the available data have not convincingiy shown those differences. The third point raised in Dr Prince’s comments deals with characteristics of epileptic neurons. Prince apparently associates the all-or-none burst shown in his Figures 1 and 2 [2) with epileptiform activity. I t is unclear, however, how many such bursting neurons were observed in their “epileptic” cortex. The cellular bursts were apparently not associated with a population discharge. If this is so, how can the occurrence of an isolated neuronal event be characterized as “epileptiform” when epilepsy may well be a population phenomenon? The burst discharge shown by Prince and Wong might be an epileptiform PDS burst, or might simply be the discharge pattern of a normal cell in temporal lobe; the data do not provide a basis for deciding which. Regarding the apparently normal appearance of intracellularly stained neurons in our study [4], Prince seems to imply that those ceils were not in the epileptic focus. Such an interpretation is somewhat tricky because it is precisely the definition of the term focus that needs clarification. If the determination of a focus can be made strictly on the basis of electrocorticographical “spikes,” then our apparently normid neurons were within the focus. We are not satisfied with this sole criterion, for ifforus were so simply defined, the success rate for neurosurgical “cures” would be much higher. Studies on characterizing a focus [ l) have shown that the problem is complex and still unresolved. We are also unsure that the morphologically abnormal neurons, which have been demonstrated in chronic foci [ S } , are the same cells that are “hyperexcitable”; perhaps those morphologically abnormal cells are too sick to discharge repeatedly, and cells with more subtle changes maintain the epileptiform activity. Dr Prince’s reaction to our paper is somewhat puzzling, for it seems clear that the published data from in vitro slice studies of human cortex cannot support an interpretation of tissue epileptogenicity. The preparation may provide a unique 011portunity to investigate cellular mechanisms 131, but to do c,o with human neurons in tissue taken from human epileptic brain does not guarantee our ability to elucidate cel1ul;;lr mechanisms of epileptogenesis. Interpretation of the data should be cautious and based on the same rigorous standards used to interpret results from any other intraccllular study.

Abstract: Many learning handicapped children have impaired language associations, patterns, and expressions. This paper summarizes relevant linguistic research and instructional strategies. A number of linguistic auditory memory pattern (LAMP) exercises and examples are then presented as an integrated multi-sensory approach which has been found useful by special educators.

Abstract: My task here is to evaluate the “auditory” perception provided to subjects fitted with single-channel cochlear implants and to contemplate the limits that such single-channel devices place on the individuals’ perceptual experience. In the pursuance of this task, I will summarize briefly the “auditory” results obtained with such subjects, relying most heavily on my own work,* and will then try to relate these findings to current theories of auditory perception and of information processing. From the standpoint of how the acoustic signals were coded electrically, it should be noted that we did not have experimental control of the encoding, but tested the subjects with the wearable stimulators as they used them routinely. Of the 12 subjects for whom data were obtained, 10 were patients of Dr. William F. House and used the Urban device, which amplitude modulated, nonlinearly, the signal voltage onto a 16-kHz carrier; while the other two were patients of Dr. Robin P. Michelson and used a device that delivered a n analog voltage to the implanted electrode. This restriction was a condition of the contract with NINCDS under which the evaluation was c0nducted.a We were permitted, however, to conduct electroacoustic studies of the stimulators as the subjects wore them.2 Thus, in interpreting my remarks about psychoacoustic performance with single-channel implants, we must bear in mind that some of my results may be idiosyncratic to the coding built into the subjects’ devices. To establish a context for the summary of results to be presented here, the masking data we obtained should be dealt with first. For hearing subjects, the introduction of a second sound, the masker, either leaves the threshold for the test signal unaffected or raises threshold. The accepted explanations for masking data assume that the hearing subject is listening through a large number of auditory channels called “critical bands.” If the hearing listener is forced experimentally to listen with a single critical band, then his data can best be explained in terms of intensive discrimination rather than masking. The masking studies we conducted on subjects using single-channel cochlear implants (masking of signals a t 250, 500, 1000, or 2000 H z by a 500-Hz tone and by a white noise) gave results that can only be explained by assuming that the subjects were listening through a single “critical” band (pp. 113-1 19). That is, the 500-Hz masker masked 2.50-, 500-, 1000-, and 2000-Hz signals equally well (in hearing subjects 250 Hz would not be masked at all by the 500-Hz masker). Further, the effect of our low-sensation level maskers was to improve threshold in most cases. If we must assume that the single-channel implant forces the subject to listen through a single “critical” band, then we must ask what the characteristics are of that band.

Abstract: The role of the auditory cortex in the localization of stationary sources was deduced from the deficit of localization ability of decorticated dogs. The lateralization threshold for stimulation by signals with interaural difference in time (delta T) and intensity (delta I) was taken as a quantitative estimate of the localization ability. These thresholds were determined for intact animals as well as for those with uni- and bilateral removal of the auditory cortex (AI, AII, Ep). The bilateral ablation has been found to disturb the temporal cue localization, whereas the delta I-cue localization has been retained. The ability of localization by the temporal cue depended on damage size (AI). The obtained data imply the importance of the auditory cortex for perception of temporal signal characteristics.