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Auditory localisation is part of central auditory processing. The study examined the impact of hearing aids on the auditory localisation ability of non-linguistic stimuli in hearing impaired schoolchildren.Above threshold acoustic signals were presented to 20 children (7-17 years) in a free field condition with 45 loudspeakers placed on a semicircular array. All participants had a bilaterally symmetric moderate sensorineural hearing loss (WHO grade 2) and used behind the ear style (BTE) hearing aids with conventional earmolds. The children had to indicate the position of the signal by a laser pointer. Both high- and low-frequency noise bursts were employed in the tests to separately address spatial auditory processing based on interaural time differences and interaural intensity differences. The examination was performed with and without BTE hearing aids.There was no significant difference between results in the aided and the unaided condition: neither for the different frequency bands nor for the signal positions. The auditory localisation of the hearing impaired children was reduced by 3°-4° for frontal and 5°-11° for lateral positions compared to normal-hearing children. There was no age-relation.In our experimental setting, BTE hearing aids could not compensate the impaired auditory localisation ability of children with sensorineural hearing loss.Die Richtungslokalisation ist eine Teilleistung der zentralen auditiven Verarbeitung. Es wurde der Frage nachgegangen, ob das Tragen von Hörgeräten die Lokalisationsfähigkeit von nichtsprachlichen Stimuli bei schwerhörigen Schulkindern unterstützt.20 Kinder (7–17 Jahre) mit einer beidseitigen, symmetrischen, mittelgradigen peripheren Schallempfindungsschwerhörigkeit (WHO-Grad 2) wurden im Freifeld mit und ohne Hinter-dem-Ohr-Hörgeräte (HG) untersucht. Alle Probanden trugen HG mit individuellen Passstücken. Die Aufgabe war, die Position überschwelliger akustischer Signale im Freifeld mithilfe eines Laserpointers innerhalb einer halbkreisförmigen Anordnung von 45 Lautsprechern anzuzeigen. Es wurden jeweils tief- und hochfrequente Stimuli getestet, um den Einfluss von interauralen Zeit- und Pegelunterschieden auf die Verarbeitung unterscheiden zu können. Die Ergebnisse wurden mit denen normalhörender Kinder verglichen.In unserem Testaufbau gab es keinen signifikanten Unterschied zwischen der Messung mit und ohne HG, weder für die unterschiedlichen Frequenzbänder noch für die unterschiedlichen getesteten Positionen. Die absolute Abweichung der schwerhörigen Kinder war um 3–4° frontal und 5–11° lateral schlechter als die hörgesunder Kinder. Wie auch normalhörende Schulkinder konnten die schwerhörigen Schulkinder frontale Positionen signifikant besser lokalisieren als laterale. Ebenso zeigte sich keine Altersentwicklung der Lokalisationsfähigkeit.In unserem Testaufbau konnten HG die schlechtere Lokalisationsfähigkeit schwerhöriger Kinder nicht ausgleichen.

Diese Arbeit beschäftigt sich mit der Richtungsbestimmung einer Schallquelle in der Horizontalebene durch ein technisches System. Es soll ein Prototyp gebaut werden, welcher durch mehrere Messmikrofone Schalldruckwellen aufnimmt und die Messdaten einer digitalen Recheneinheit übergibt. Aus den gespeicherten Messdaten soll in Echtzeit der Schalleinfallswinkel in der Horizontalebene bestimmt werden. Der berechnete Schalleinfallswinkel soll in Echtzeit als grafischer Pfeil auf einem Display ausgegeben und laufend mit angemessener Verzögerung aktualisiert werden. This thesis deals with the directional determination of a sound source in the horizontal plane using a technical system. A prototype is to be built, which records sound pressure waves through several measurement microphones and transfers the measurement data to a digital computing unit. The sounds angle of incidence in the horizontal plane is to be determined from the stored measurement data. The calculated angle is to be shown in real time as a graphic arrow on a display and is to be updated continuously with a reasonable delay.

Patients with single-sided deafness (SSD) lack the ability localize sound sources and have difficulty with speech-in-noise hearing. In addition, there is a high prevalence of tinnitus distress. These problems may result in reduced health-related quality of life (HRQoL) and psychological comorbidities. This study aimed to investigate the influence of treatment with a cochlear implant (CI) on HRQoL, tinnitus distress, psychological comorbidities, and audiological parameters in SSD patients.This retrospective study included 20 patients with postlingually acquired SSD (13 women, 7 men, mean age 57.0 years). Data on HRQoL were collected with the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Medical Outcome Study Short Form 36 Survey (SF-36). Tinnitus distress was assessed with the Tinnitus Questionnaire (TQ), psychological comorbidities were evaluated with validated questionnaires, and speech perception and hearing ability were measured with validated speech tests.Postoperatively, the mean total NCIQ score (p 0.0001) and four subscores improved significantly, as did tinnitus distress (p 0.05). Anxiety symptoms (Generalized Anxiety Disorder questionnaire, GAD-7) decreased significantly after CI. Speech perception improved significantly, particularly "hearing with background noise" (p 0.05, Oldenburg Inventory, OI) and "localization" (p 0.001, OI), as well as the Oldenburg Sentence Test (OlSa) scores for with vs. without CI when speech was presented from the SSD side and noise was presented from the normal hearing side (SCI in SSD patients is a powerful procedure to improve HRQoL, reduce tinnitus distress, and improve psychological comorbidities. Additionally, it is beneficial for hearing improvement, particularly in noise and for directional hearing.

Sound localization is necessary for social interaction and remains challenging for bilateral cochlear implant (CI) users. This study investigated the influence of fine structure processing (FSP) coding strategies on temporal accuracy and source localization. The ability to discriminate between different interaural time differences (ITD) was measured objectively and compared.Fifteen normal-hearing subjects and five CI users participated in this study. Electrophysiological recording of mismatch negativity (MMN) and psychoacoustic tests with headphones and loudspeakers were conducted to measure and compare the discrimination of ITDs.In normal-hearing subjects the discrimination threshold for ITD was 83-117 µs. Localization ability in a free sound field was below the limit of resolution. A significant MMN was measured. CI users showed a mean angle detection error of more than 30° and a discrimination threshold between 1100 and 2100 µs. Due to artifacts, no clear MMN component could be recorded.This study shows that MMN can be used as an objective measure of ITD discrimination in normal-hearing participants. An indication that improvements in directional hearing can be achieved with the transfer of fine structure could not be provided by this study.

Test procedures used in clinical routine are often not sufficiently accurate to evaluate the auditory benefit of hearing systems and the improvements brought by new signal preprocessing algorithms.The aim of the study was to realize and evaluate a sound reproduction system for simulation of everyday listening conditions.A sound reproduction system was developed using 128 loudspeakers. By appropriate superposition of the loudspeaker signals (so-called wave field synthesis), it is possible to create almost arbitrary everyday listening conditions in a reproducible laboratory setting. Auditory scenes can be changed in real time. The sound reproduction system was mechanically evaluated by measuring the sound field with a microphone array. To validate the system, speech reception thresholds (SRT) were measured in bilateral cochlear implant (CI) users in moving and diffuse noise conditions. Furthermore, the impact of different types of directional microphones on speech perception was assessed.With a moving noise source in the dorsal half-space, CI users showed significant SRT improvements by using directional microphones with higher directional sensitivity (2.5 dB improvement) as well as with adaptive directional sensitivity (8.5 dB). The benefit of adaptive directional microphones is reduced in environments with diffuse noise.Wave field synthesis is a useful tool to simulate everyday listening conditions in a reproducible laboratory environment. This technique can complement established clinical methods to assess the benefit of a hearing device fitting or of signal preprocessing algorithms in dynamic listening conditions.

The delivery of directional cues of a hearing device microphone are highly dependent on the position of the microphones. The aim of this work was the evaluation of different microphone positions with regard to the transmission of interaural time and level differences as well as the spectral characteristics and its impact on the localization abilities.Head-related transfer functions of 30 subjects were measured with three different omnidirectional microphones at different positions: in the pinna (ITP), behind the ear (BTE), at the entrance of the ear canal (EEC). Sound localization abilities of 12 bilateral CI users was assessed for the microphone positions ITP and BTE.Only the microphone positions in the ear (ITP, EEC) could sample the spectral cues of the pinna. However, the positioning of the microphone inside of the pinna did not significantly improve sound localization abilities compared to BTE microphones. For sound incidence from rear significantly less front-back confusions were achieved with the microphone inside of the pinna.The microphone position in the pinna showed only a slight improvement in sound localization compared with BTE microphones in CI users. A precondition for better sound localization abilities is the improvement of the delivery of temporal and spectral fine structure cues in CI systems.Je nach Position der Mikrofone von Hörhilfen werden die für die Schalllokalisation wichtigen richtungsbestimmenden Merkmale eines Schallereignisses unterschiedlich gut übertragen. Ziel dieser Arbeit war die messtechnische Evaluation verschiedener Mikrofonpositionen hinsichtlich der Übertragung von interauralen Zeit- und Pegeldifferenzen sowie der spektralen richtungsabhängigen Merkmale und deren Einfluss auf die Genauigkeit der akustischen Lokalisation.Es wurden von 30 Personen kopfbezogene Übertragungsfunktionen mit drei verschiedenen omnidirektionalen Mikrofonen gemessen, die unterschiedlich positioniert waren: in der Ohrmuschel (IdO), hinter dem Ohr (HdO), am Eingang des äußeren Gehörgangs (EdG). Weiterhin wurde bei 12 bilateralen Cochlea-Implantat-Nutzern die Lokalisationsleistung bei zwei Mikrofonpositionen bestimmt.Nur die Mikrofonpositionen innerhalb der Ohrmuschel (IdO, EdG) konnten die spektralen Filtereffekte der Pinna aufzeichnen. Ungeachtet der besseren Abtastung der Pinnafunktion führte die Mikrofonposition IdO bei CI-Nutzern nicht zu einer besseren Lokalisationsleistung gegenüber HdO-Mikrofonen. Bei rückwärtiger Schalldarbietungen ergaben sich jedoch signifikant weniger Vertauschungen mit der frontalen Einfallsrichtung.Die Mikrofonposition im Ohr zeigte bei CI-Nutzern nur eine geringfügige Verbesserung der akustischen Lokalisation gegenüber den gewohnten HdO-Mikrofonen. Als Grundvoraussetzung zur Verbesserung der Lokalisationsleistung erscheint eine verbesserte Übertragung der zeitlichen und spektralen Feinstruktur in CI-Systemen erforderlich.

The sensory-motor system is crucial for the interaction of an organism with the environment. To be able to accomplish this interaction, it is essential to combine information from different sensory systems, for example information of the visual system, which betray information about the position of both the desired object as well as the arm, with proprioceptive information of the motor system. This combination is the basis for a correct motor command (Baraduc&Wolpert, 2002). Generally, in goal-driven pointing/throwing movements, information from the visual and the proprioceptive system normally correspond. Therefore, a pointing respectively throwing movement towards an object occurs without any problems (Kitazawa, Kohno,&Uka, 1995). But looking through prism glasses changes the position of the eyes relative to the head. This results in an initial pointing/throwing movement error in direction of the prismatic shift, the object is missed sideways (Efstathiou, 1969; Guan&Wade, 2000; Harris, 1963; Harris, 1965; Redding, Rossetti,&Wallace, 2005; Redding&Wallace, 2006; Taub&Goldberg, 1973). This mismatch occurs because spatial coordinates of the visual and proprioceptive system no longer match (Bornschlegl, Fahle,&Redding, 2012; Redding&Wallace, 1990; Redding&Wallace, 1993). However, to restore the previous conditions, the organism is able to adapt to the new conditions, in this case to the prismatic shift. The spatial coordinates will be adjusted gradually, by pointing/throwing under visual feedback (Baraduc&Wolpert, 2002; Bornschlegl, Fahle,&Redding, 2012; Cohen, 1967; Efstathiou, 1969; Harris, 1963; Harris, 1965; Hay&Pick, 1966; Redding, Rossetti,&Wallace, 2005; Redding&Wallace, 2006; Taub&Goldberg, 1973). After removing the prisms, again a point movement occurs, now opposite to the prismatic displacement (Cohen, 1967; Guan&Wade, 2000; Redding, Rossetti,&Wallace, 2005; Taub&Goldberg, 1973). It can be reduced gradually under visual feedback, with the result that the spatial coordinates are adjusted again. The adaptation of the eye-hand coordination, more specifically the prism adaptation, at the first glance seems to be a relative simple process, which allows a fast error correction. But a more detailed look shows a complex system. For a better understanding of this complex system, since Helmholtz (1867) a large number of studies have been conducted on this topic. But despite this variety of studies and their methods, until today some basic questions were not answered satisfactorily. These include 1) the not quite understood immediate correction effect, 2) the question to what extend it is connected with the body rotation and/or subconscious head- and eye position and 3) the question whether or not prism adaptation has an influence on the auditory system. The present dissertation deals with the aforementioned unsolved questions in prism adaptation.

The rehabilitation of patients with single-sided deafness (SSD) or asymmetric hearing loss can be achieved with conventional (bilateral) contralateral routing of signals ((Bi)CROS) hearing aids ((Bi)CROS-HA, (Bi)CROS), bone-anchored hearing systems (BAHS) or cochlear implants (CI). To date, only small case series have been published on treatment outcomes in SSD patients after CI surgery and there are only a few comparative studies evaluating rehabilitation outcomes.The aim of this study was to provide evidence of successful treatment of SSD and asymmetric hearing loss with a CI compared to the untreated monaural hearing condition and the BAHS and (Bi)CROS treatment options in a large number of patients.In a single-centre study, 45 patients with SSD and 40 patients with asymmetric hearing loss were treated with a CI after careful evaluation for CI candidacy. Monaural speech comprehension in noise and localisation ability were examined with (Bi)CROS-HA and BAHS devices (on a test rod) both preoperatively and at 12 months after CI switch-on. At the same intervals, subjective evaluation of hearing ability was conducted using the Speech, Spatial and Qualities of Hearing Scale (SSQ).This report presents the first evidence of successful binaural rehabilitation with CI in a relatively large patient cohort and the advantages over (Bi)CROS and BAHS in smaller subgroups, thus confirming the indication for CI treatment. Moreover, patients with long-term acquired deafness (10 years) show a benefit from the CI comparable to that observed in patients with shorter-term deafness.

The influence of bilateral cochlear implants (CI) and unilateral CI on the self-reported listening effort in standardized situations is being assessed.The sample consisted of 34 bilateral and 38 unilateral adult CI users. Unilateral CI users had at least severe hearing loss in the non-implanted ear and had been fitted with a hearing aid. The listening effort has been defined as a subjectively perceived effort in understanding a speaker. Patients were administered a customized questionnaire containing nine examples of listening situations with different demands. The listening effort expended in each situation had to be rated on a six-step scale. Answers were analyzed using repeated measures ANOVA, including the factors "level of background noise," "listening duration," and the covariates "patient age" and "time since CI implantation."Only the factors "level of background noise" and "listening duration" were significant (p = 0.024 and p = 0.001 respectively). Unilateral versus bilateral CI was not significant (p = 0.17). Nevertheless, bilateral CI users reported a lower degree of listening effort than unilateral users in all of the nine situations asked about in the questionnaire (binomial test: p = 0.002).We conclude that bilateral CI use has some effect on reducing listening effort, but compared with unilateral use the effect is possibly not very great.

Auditory deficits may be at the core of the language delay in children with Specific Language Impairment (SLI). It was therefore hypothesized that children with SLI perform poorly on 4 tests typically used to diagnose central auditory processing disorder (CAPD) as well in the processing of phonetic and tone stimuli in an electrophysiological experiment.14 children with SLI (mean age 61,7 months) and 16 children without SLI (mean age 64,9 months) were tested with 4 tasks: non-word repetition, language discrimination in noise, directional hearing, and dichotic listening. The electrophysiological recording Mismatch Negativity (MMN) employed sine tones (600 vs. 650 Hz) and phonetic stimuli (/ε/ versus /e/).Control children and children with SLI differed significantly in the non-word repetition as well as in the dichotic listening task but not in the two other tasks. Only the control children recognized the frequency difference in the MMN-experiment. The phonetic difference was discriminated by both groups, however, effects were longer lasting for the control children. Group differences were not significant.Children with SLI show limitations in auditory processing that involve either a complex task repeating unfamiliar or difficult material and show subtle deficits in auditory processing at the neural level.

A child has the first 4 years of life in which to develop speech. The first 8-10 months see the ability to distinguish sounds; later comes further linguistic ability. A hearing impairment more than 25 dB in the better ear in the speech frequencies (500-4 000 Hz) for more than 3 months has clear consequences, especially in the first 4 years of life. Therefore early diagnosis and treatment with rehabilitation of hearing loss is important for proper speech development.

In Germany testing auditory low level skills has gained some popularity. However only few studies have provided norms. Prior to further testing we here aimed at establishing normal values for school children.prospective study.School children attending 3rd and 4th grade.just noticeable differences for intensity and frequency (JNDI, JNDF), gap detection (GD) monaural and binaural temporal order judgement (TOJB and TOJM).descriptive and correlational analysis.Data did not follow a normal distribution, i. e. only few children had poor results whereas the majority of children had fair to excellent results. Correlational analysis indicated some dependency among auditory low level skills as tested here.These data are consistent with previously described data that auditory low levels maturate during development at least up to age 10. However the significance of poor results for impaired language acquisition remains unclear.

Azimuthalortung lässt sich, insbesondere im tieffrequenten Spektralbereich, auf die Bestimmung interauraler Zeitdifferenzen (ITDs) zurückführen. Die dafür relevanten Frequenzen liegen, je nach Tier, im Bereich zwischen 20 Hz und 9 kHz. Die vorliegende Arbeit untersucht, wie unterschiedliche Arten der neuronalen Repräsentation des Stimulusazimuths über synaptische Entwicklung im heranwachsenden Tier entstehen können. Dazu werden sowohl Computersimulationen, als auch analytische Betrachtungen zur Dynamik der synaptischen Verbindungen herangezogen. Es werden zwei, zunächst konträr erscheinende, neuronale Modelle zur Repräsentation interauraler Zeitdifferenzen vorgestellt. Das erste geht zurück auf Jeffress (1948), der ein Netzwerk postulierte, welches die Stimulus-ITD topographisch auf den Ort derjenigen Zelle abbildet, die mit höchster Rate feuert. Ein derartiges Raten-Orts-Prinzip nennt man auch Karte. Die Schleiereule ist ein bekanntes Beispiel für ein Tier, das derartige ITD-Karten besitzt. Es wird gezeigt, wie ein spezieller Lernalgorithmus die Jeffress-Karte der Schleiereulen erklären kann. Das zweite hier diskutierte Modell zur ITD-Repräsentation wurde von McAlpine (2001) vorgeschlagen, der die Idee von Bekesys (1930) aufgriff, dass die Stärke der neuronalen Aktivierung einer dazu geeigneten Zellgruppe eine monotone Funktion des Stimulusazimuths ist. Dabei codieren hohe Feuerraten einen Azimuth auf der contralateralen Seite, niedrige Feuerraten einen Azimuth auf der ipsilateralen Seite. Um die Jeffressche Karte zu erklären, kombinieren wir eine homosynaptische Lernregel, die Tuningkurven mit der hohen zeitlichen Präzision weniger 10 Microsekunden erklären kann, mit einem präsynaptisch unspezifischen Anteil, der als axonvermitteltes synaptisches Lernen (AMSL) bezeichnet wird. Dabei werden alle synaptischen Veränderungen zu einem kleinen Prozentsatz auch allen anderen Synapsen ein und desselben Axons aufgeschlagen. Dieser Lernmechanismus und die spezielle Anatomie des Nucleus Laminaris, der ersten Station in der aufsteigenden Hörbahn, die neuronale Aktivität von beiden Ohren erhält, schaffen die Voraussetzungen für eine sich selbstorganisierende Entwicklung einer ITD-Karte, in der benachbarte Zellen Zeitdifferenzen mit wenigen Microsekunden Unterschied kodieren. Die Lernprozedur wählt hierbei Axone nach ihren Verzögerungszeiten so aus, dass die zeitliche Dispersion der in mehreren 100 Nervenfasern entlang laufenden neuronalen Aktivität stark reduziert wird. Analytische Überlegungen vervollständigen das Bild, wie AMSL zur Kartenbildung beiträgt und stellen auf abstrakterer Ebene eine Grundlage bereit, die die Auswirkungen neuronalen Rauschens und der Modellparameter auf die Synapsendynamik verstehen lässt. So ist es möglich, eine Obergrenze für die Stärke des axonvermittleten Lernens abzuschätzen. Auch kann gezeigt werden, wie nichtlineare Neuronmodelle Vorteile bei der axonalen Verzögerungsselektion besitzen. Das zweite neuronale Modell, welches wir behandeln, wurde von McAlpine (2001) vorgeschlagen. Seine Messungen im Meerschweinchen zeigen auf, dass die Zellen alle bei etwa derselben ITD maximal antworten und so eine Jeffress-Karte ausschließen. Das daraus gefolgerte Ratengradientenprinzip wird durch synaptische Lernregeln realisiert, wenn man gleichzeitige exzitatorische und inhibitorische Plastizität annimmt. Eine Ausweitung des Ratengradientenmodells auf das ursprüngliche von Bekesy-Modell, welches neben dem Ratengradienten- auch einen Orts-Code beinhaltet, ist ebenfalls durch AMSL möglich. Damit lässt sich, abhängig vom evolutorischen Druck auf die Präzision der Azimuthalortung und dem Kopfdurchmesser, ein gradueller Übergang des Repräsentationsprinzips vom Ratengradienten- zum Kartenmodell verstehen. Als Verbindungsglied zwischen beiden Extremen dient das von Bekesy-Modell. Tiere mit kleinem Kopfdurchmesser und wenig ausgeprägtem Lokalisationsvermögen sollten dabei vorzugsweise die Azimuthalortung anhand des Ratengradientenmodells bestreiten, Tiere mit größerem Kopf oder hohem Lokalisationsvermögen verwenden einen Raten-Orts-Code. Localization of a sound stimulus' azimuth may be, and in the low-frequency range is, performed through detection of interaural time differences (ITDs) in appropriate neurons. Here the relevant signals are in a range between 20 Hz and 9 kHz and temporal structures of sound are coded through phase-locked activity. The present work explains how different neuronal representations of the stimulus azimuth arise during maturation of an animal. To this end, both computer simulations and analytical treatment are used to investigate the dynamics of synaptic transmission. The thesis introduces two, at a first glance contradictory, neuronal models for the representation of ITDs. The first dates back to Jeffress (1948), who proposed a network of neurons that topographically map an ITD onto the position of the cell firing at the highest rate. Such a rate-place code of the outside world is often referred to as a map. A well-known example of an animal providing a Jeffress map is the barn owl. It is shown how a specific learning algorithm can account for the development of the ITD map in barn owls. The second model analyzed here is due to McAlpine (2001), who adopted an idea of von Bekesy (1930) that the amount of neuronal activity in the relevant brain structure monotonically represents the stimulus azimuth. This is done in such a way that a high firing rate codes an azimuth at the contralateral side whereas a low firing rate codes one at the ipsilateral side. In order to explain Jeffress' map, we combine a well-know homosynaptic learning rule, which is known to generate a microsecond-precision tuning curve of single cells, with a presynaptic unspecific component, which we call axon-mediated synaptic learning (AMSL). The latter transmits a small fraction of any synaptic change to all other synapses connected to the same axon. This learning procedure and the specific anatomy of the laminar nucleus, the first station of the ascending auditory pathway receiving neuronal activity from both ears, provide the basis for the self-organizing development of an ITD map, where neighboring cells code ITDs that differ by a few microseconds. Learning, i.e., synaptic plasticity, is selecting axons with respect to their delays in such a way that temporal dispersion of neuronal activity conducted through hundreds of nerve fibres is strongly reduced. Theoretical analysis reveals how AMSL supports map formation and, at a higher level, provides a framework for understanding the effects of noise and parameters of the neuron model as they appear in synaptic dynamics. Specifically, it is shown how to estimate an upper limit for the strength of axon-mediated synaptic learning. It is possible to understand how nonlinearities of the neuronal model provide a beneficial effect for axonal delay selection. The second neuronal model that is treated in this work has been proposed by McAlpine (2001). His experiments on guinea pigs have revealed that all cells respond maximally to about the same ITD, a fact contradicting Jeffress' hypothesis. We demonstrate that the resulting, so-called rate-gradient, idea can be explained by plasticity of both excitatory and inhibitory synapses. An extension of the rate-gradient model to the original von Bekesy idea, incorporating a rate-place component as well, has been performed, again through AMSL. It is argued that, depending on the evolutionary necessity of localization precision and the animal's head size, there may be a gradual change in neuronal ITD detection from the rate-gradient to the Jeffress' principle in dependence upon various parameters characterizing the animal. The extension, now called the von Bekesy model, could be the link between them. As a consequence, we propose that animals with a small head diameter or limited acuity are likely to use the rate-gradient concept for azimuthal sound localization whereas those with larger diameter or higher acuity employ the rate-place algorithm.

Central auditory processing disorders (CAPD) are associated with reduced discriminatory abilities of the auditory system. One of these abilities is directional hearing, which is based on the evaluation of interaural signal differences. Since these differences affect also the binaural difference potentials (BDP), these derived evoked potentials could be suitable for the objective detection of disabilities in acoustic localization.Auditory brainstem responses (ABR) evoked by monaural and binaural stimulation were recorded in 32 adult normal-hearing volunteers at stimulus levels between 10 and 80 dB nHL and the BDP were derived. Additionally, a test of directional hearing was performed and evaluated.BDP are detectable at all stimulus levels without difficulties, with acceptable examination times and with satisfactory reliability in a routine clinical environment. The electrodes can be positioned at the mastoid (A1 and A2) and vertex (Cz) as for conventional ABR recording. Normal ranges are given for latency and amplitude as well as for their lateral differences.The spectrum in directional hearing ability as covered by normal-hearing subjects is not mirrored in the parameters of their BDP. Nevertheless, it cannot be ruled out that a real impairment of directional hearing goes along with significantly altered BDP.

It has been suggested that training in temporal processing may significantly improve language processing and reading skills. However, improvement effects of training on language impairment or dyslexia have not been proven so far. In the present study a temporal processing training was evaluated.The participants of the present study were 42 children (5th graders) of a special school for children with reading and spelling problems. Children of one class (n = 21) were assigned to a training group (n = 21), the other class to a control group. Children in the training group took part in a training program consisting of auditory and visual order threshold and sound localisation tasks, over a period of eight weeks. We determined the order thresholds, sound localisation ability and reading and spelling performance of all children before and after the training period. Six months later all subjects were re-tested.Auditory and visual order thresholds decreased significantly more in the training group than in the control group. However, these changes were not accompanied by improvements in reading or spelling skills.In the present study no training effects on reading and writing performance were observed by using a program including temporal processing tasks. It is questionable whether training programs of temporal processing are useful methods in therapy of dyslexic children.

More than ever before the neonatal care besides the medical and nursing work has to been balanced between protecting the child against over extension due to the concept of "minimal handling" and on the other hand the necessary fostering of the young patients psychic and sensomotor development during the long stationary treatment. In addition to known approaches of auditive stimulation as receptive music therapy a concept of active music therapy methods based on the Nordoff/Robbins creative music-therapy (University Witten/Herdecke) is presented in a case-report.The report describes in a single case-report the music-therapeutic work with a premature of the 23 + 3 (th) week of pregnancy at the neonatological unit of the Vestische Kinder- und Jugendklinik Datteln, Universität Witten/Herdecke. The main focus was the observation of the prematures reactions on specific synchronisation of motoric, sensor and acoustical stimulation.Positive reactions allow to presume the effectiveness of music therapy with early born children as they are already shown in clinical studies about receptive music therapy. On the level of involuntary motional actions in the area of head-, face- and hand movements increased directly reactions of awareness on the coordination of sensomotor and acoustical stimulation have been observed. Temporary increase of oxygen partial pressure and reduction of heart/pulse rate seem to cause positive physiological effects.Active music therapeutic treatment does not seem to be an other risk of over-tension for prematures, but offers through the coordination of different levels of perception an adequate development fostering stimulation.

Having two ears instead of just one is advantageous in several respects. The danger of deafness is decreased, the auditory field is enlarged, spatial perception is possible on the basis of binaural disparities. Auditory deprivation presents as loss of discrimination over time in the unaided ear of individuals with a unilateral hearing loss. Earedness and ear preference ensure the choice of the dominant ear for definite actions like eavesdropping, telephone or listen.

Prevention and early detection of deficits of the developing human being demand more and more complex solutions. Screening programmes have been developed to detect deficits and diseases before they cause symptoms. A well-organised and accurately performed screening programme can detect preliminary signs of diseases and may prevent irreversible damage. Early detection of deficits only makes sense if it is followed by consequences. Not only early detection of impairment or of children which are threatened by impairment is a very important medical task, but also the interdisciplinary cooperation in therapy. The most serious impact of hearing deficits in newborn is on the lack of speech-acquisition. It is an indisputable fact that the early detection of hearing impairment in newborn markedly improves the prognosis for further language development if early medical and/or rehabilitative therapy takes place. The following description of 10 years of experience with a newborn hearing screening programme that is effected in cooperation with the maternity ward and the ENT-clinic since 1981, can supply further arguments in favour of the need for early detection, the discussion on reflex audiometry, and to emphasise the need for cooperation of all relevant specialists.

Simulation free field hearing by head phones by means of digital filter technics was used to investigate directional hearing and audiocinetic vection in microgravity. Our data showed basic informations for the understanding of the reciprocal influence of vestibular and auditory inputs for dynamic orientation. The technical equipment of free field hearing simulation by headphones and the performed experiments are described in detail. Furthermore the new established technology is discussed in terms of the value in psychoacoustic research as well as in clinical practice.

Auditory evoked brain-stem responses were recorded using binaural stimulation on 12 test subjects. Rotation of the sound source in the horizontal plane was simulated digitally using a binaural mixing console. Binaural processing in the inferior colliculus was thus demonstrated in humans. The amplitude of the inferior colliculus response depends in an almost linear manner on sound direction and presents a typical directionality. While the amplitude is considered an important central code of sound direction, response latency of the inferior colliculus is controversial. The results confirm neuronal mechanisms which had been established by animal experiments for single units of the inferior colliculus and the auditory cortex.

An 83-year-old woman experienced the abrupt onset of musical hallucinations. She had had long-standing progressive hearing loss due to otosclerosis. The clinical, psychopathological and pathogenetic aspects of this syndrome are discussed by means of a review of the literature.

Good directional hearing ability demands good and symmetrical hearing in both ears. We report the effect of impaired hearing on the directional hearing ability of 98 patients, especially of patients with bilateral asymmetrical hearing loss. The directional testing device included 12 loudspeakers placed at 30 degree intervals in a circle with a diameter of 3.25 m, whose centre lay between the ears of the patient. In included an audiometer for producing the signals, an amplifier and a PDP11/23 computer interfaced to a loudspeaker switch bank. The subject's answers to 60 directionally randomized stimuli were recorded. During the presentation of the signal the patients were not allowed to turn their head. The patients had to name the number of the loudspeaker on the circle that they thought was producing the sound. In addition to the directional hearing test a pure-tone audiogram was done, and the middle- and high-frequency hearing loss estimated. The records of the directional hearing test were analysed in two new ways: firstly, vector analysis of the errors; secondly, averaging of the difference between the true interaural time delay and the virtual time difference, which was implicated in the possibly incorrect answer of the patient (effective delta-t-parameter). This average gives a score for the uncertainty in defining the correct "cone of confusion". In addition to the statistical analysis, two cases are reported showing the directional hearing ability of two patients with neuromas treated by transtemporal surgery, with some residual hearing.(ABSTRACT TRUNCATED AT 250 WORDS)

A new method for evaluation of hearing threshold in babies is presented. The method does not require much time, cost or personnel and is practicable for infants up to about 12 months. It is based on synchronous electrical registration of sucking and breathing activities as well as of eye movements evoked by acoustic stimuli. Sucking and breathing are reduced by supra-threshold stimuli, preparing the baby for attentive listening. Eye movements are directed towards localizing the site of the stimulus.

For demonstrating the influence of cerebral growing old on directional hearing three groups of 20--30 years, 40--50 years and 70--90 years old persons have been tested. It could be shown that the ability to differentiate small changes of direction was diminished, the old persons recognized only changes of 50 degrees and 60 degrees to 100%. The indication to applicate a stereophonic hearing aid has been discussed and the importance to select patients by testing directional hearing for fitting binaural aids is emphasized.

In 10 healthy individuals the influence of a rotating sound source (loudspeaker, narrow band noise 500 Hz, 70 dB SPL, 120 degrees/sec.) on the postrotatory nystagmus was investigated. If the loudspeaker was rotating in the opposite direction of the fast postrotatory nystagmus component, the duration and intensity of the postrotatory nystagmus was amplified by about 30%. If the loudspeaker was rotating in the direction of the fast postrotatory nystagmus component, no changes were seen.

The directional hearing of 20 healthy test persons, all with normal hearing abilities, was tested using a special self constructed equipment. Under the repeated influence of an optokinetic stimulation (rotating light beams on a semicircular screen in a completely darkened room) no statistically significant deviation of the directional hearing reactions could be detected.

Hearing screening with reactometry in the newborn is now being considered too expensive and fails to detect quite a number of deaf children. Conversely, experiences at the age of 8 months with BOEL-Test (a distraction test, which yields further information on visual and neurological deficiencies) have shown that it becomes possible to detect the majority of hearing defects. As this age level is quite adequate for diagnosis even of defects arising in the first year (progressive genetic deafness, deafness due to infections etc.) and considering that rehabilitation can start only after this term, the authors suggest to reserve neonatal screening only for risk cases and to retest all children with the BOEL-Test.

This review presents recent findings on the micromechanics of the basilar membrane. Active processes are essential for basilar membrane motion. It may be that contractile proteins within the outer hair cells play an important role for this amplification. The coding of acoustic information within the auditory nerve depends on spectral analysis (place information) as well as on the time structure of the stimulus. This latter time analysis seems to play a major role.

Interaural differences of time and intensity do not explain the good directional hearing capacity of persons with one deaf ear or asymmetric hearing loss. These persons estimate the direction of sounds by head movements. The alteration of sounds depends on the amplitude of the head movement, on the degree of turning the head and on a normal vestibular system. The influence of vestibular stimulation on directional hearing and the resulting virtual alterations on the direction of sound could be demonstrated.

The A-V-R-test is accomplished in a free sound field, either with a play audio-metric table (clinical use) or with a textile paravent (practice). The main effort of this reactiontest is the auditive-visual determination. The examiner provokes the auditive readiness with a supraliminal impulse, which prepares the starting position for offering an acoustic test impulse in a low signal strength on the left or right side. If the test is realized with the textile paravent, frequency and intensity proved music instruments or other sound producing objects (bunch of keys, Ewing-rattle, etc.) are offered to the child. If the A-V-R-test is accomplished with the play-audio-metric table, the tester presents a frequency specific narrow band noise to the examinee. Only the turn of the infant's head towards the source of the sound is evaluated. Infants older than 2 years may show specific reactions, depending on the stage of their development.