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This volume brings together noted scientists who study presbycusis from the perspective of complementary disciplines, for a review of the current state of knowledge on the aging auditory system. Age-related hearing loss (ARHL) is one of the top three most common chronic health conditions affecting individuals aged 65 years and older. The high prevalence of age-related hearing loss compels audiologists, otolaryngologists, and auditory neuroscientists alike to understand the neural, genetic and molecular mechanisms underlying this disorder. A comprehensive understanding of these factors is needed so that effective prevention, intervention, and rehabilitative strategies can be developed to ameliorate the myriad of behavioral manifestations.
Efferent sensory systems have emerged as major components of processing by the central nervous system. Whereas the afferent sensory systems bring environmental information into the brain, efferent systems function to monitor, sharpen, and attend selectively to certain stimuli while ignoring others. This ability of the brain to implement these functions enables the organism to make fine discriminations and to respond appropriately to environmental conditions so that survival is enhanced. Our focus will be on auditory and vestibular efferents, topics linked together by the inner ear connection. The biological utility of the efferent system is striking. How it functions is less well understood, and with each new discovery, more questions arise. The book that is proposed here reflects our vision to share what is known on the topic by authors who actually have made the observations.
Cochlear implants are currently the standard treatment for profound sensorineural hearing loss. In the last decade, advances in auditory science and technology have not only greatly expanded the utility of electric stimulation to other parts of the auditory nervous system in addition to the cochlea, but have also demonstrated drastic changes in the brain in responses to electric stimulation, including changes in language development and music perception. Volume 20 of SHAR focused on basic science and technology underlying the cochlear implant. However, due to the newness of the ideas and technology, the volume did not cover any emerging applications such as bilateral cochlear implants, combined acoustic-electric stimulation, and other types of auditory prostheses, nor did it review brain plasticity in responses to electric stimulation and its perceptual and language consequences. This proposed volume takes off from Volume 20, and expands the examination of implants into new and highly exciting areas. This edited book starts with an overview and introduction by Dr. Fan-Gang Zeng. Chapters 2-9 cover technological development and the advances in treating the full spectrum of ear disorders in the last ten years. Chapters 10-15 discuss brain responses to electric stimulation and their perceptual impact. This volume is particularly exciting because there have been quantum leap from the traditional technology discussed in Volume 20. Thus, this volume is timely and will be of real importance to the SHAR audience.
This volume, Computational Models of the Auditory, will have at its unifying theme a systems approach where the focus will be on studies whose intent is to contribute to the big picture of hearing. In effect, the work covered in this volume, and the volume itself, will build a global model of audition. The chapters will, rather than focusing on details of individual components of the hearing system, address the concerns of readers and researchers who want to know how the system works as a whole.
We live in a complex and dynamically changing acoustic environment. To this end, the auditory cortex of humans has developed the ability to process a remarkable amount of diverse acoustic information with apparent ease. In fact, a phylogenetic comparison of auditory systems reveals that human auditory association cortex in particular has undergone extensive changes relative to that of other species, although our knowledge of this remains incomplete. In contrast to other senses, human auditory cortex receives input that is highly pre-processed in a number of sub-cortical structures; this suggests that even primary auditory cortex already performs quite complex analyses. At the same time, much of the functional role of the various sub-areas in human auditory cortex is still relatively unknown, and a more sophisticated understanding is only now emerging through the use of contemporary electrophysiological and neuroimaging techniques. The integration of results across the various techniques signify a new era in our knowledge of how human auditory cortex forms basis for auditory experience. This volume on human auditory cortex will have two major parts. In Part A, the principal methodologies currently used to investigate human auditory cortex will be discussed. Each chapter will first outline how the methodology is used in auditory neuroscience, highlighting the challenges of obtaining data from human auditory cortex; second, each methods chapter will provide two or (at most) three brief examples of how it has been used to generate a major result about auditory processing. In Part B, the central questions for auditory processing in human auditory cortex are covered. Each chapter can draw on all the methods introduced in Part A but will focus on a major computational challenge the system has to solve. This volume will constitute an important contemporary reference work on human auditory cortex. Arguably, this will be the first and most focused book on this critical neurological structure. The combination of different methodological and experimental approaches as well as a diverse range of aspects of human auditory perception ensures that this volume will inspire novel insights and spurn future research.
This volume will provide an important contemporary reference on hearing development and will lead to new ways of thinking about hearing in children and about remediation for children with hearing loss. Much of the material in this volume will document that a different model of hearing is needed to understand hearing during development. The book is expected to spur research in auditory development and in its application to pediatric audiology.
Loudness is the primary psychological correlate of intensity. When the intensity of a sound increases, loudness increases. However, there exists no simple one-to-one correspondence between loudness and intensity; loudness can be changed by modifying the frequency or the duration of the sound, or by adding background sounds. Loudness also changes with the listener's cognitive state. Loudness provides a basic reference for graduate students, consultants, clinicians, and researchers with a focus on recent discoveries. The book begins with an overview of the conceptual thinking related to the study of loudness, addresses issues related to its measurement, and later discusses the physiological effects of loud sounds, reaction times and electrophysiological measures that correlate with loudness. Loudness in the laboratory, loudness of steady-state sounds and the loudness of time-varying sounds are also covered, as are hearing loss and models.
The middle ear plays a vital role in the sense and sensitivity of hearing. Of the various characteristics that distinguish mammals from other vertebrates, several pertain specifically to the middle-ear system, such as the presence of three middle-ear bones and the four-layer composite structure of the tympanic membrane. The Middle Ear attempts to elucidate the role this system plays in sound transmission, as viewed from both scientific and clinical perspectives.
The increasing prevalence of musical stimulation in our everyday environment makes studies of musical listening, comprehension and memory important. Music has simply become a pervasive aspect of the experienced environment for most of us; along with enhanced levels of machine sounds, musical sound sources are contributing to a virtual transformation of contemporary soundscapes occurring in many industrial countries. In spite of such trends, arguably the mainstream research in psychology and related fields has been slow to devote concentrated attention to this phenomenon and what it might mean. As a result, with respect to more established fields of research (e.g., visual perception, speech perception, attention and memory etc.), less is known about how people perceive and respond to complex, non-random, acoustic signals found in musical events. Although these topics reside in the domain of music research, this field is a relatively new one, with a history that dates back only about 25 years. Nevertheless, it is now a vibrant and rapidly growing field that draws from multiple disciplines (psychology, psychoacoustics, computer science, music theory, and so forth) to seek answers to questions about how we listen to musical events in our world. It tackles questions about pitch perception in complex patterns, about the role of tonal schemes as well as effects of metrical and rhythmic schemes on musical listening behaviors. It also examines abilities of children and adults to perceive and comprehend dynamic sound patterns. Emotional responses to music are also studied; and overarching all of this are exciting new neuroscience findings concerned with neural responses to musical events. Music Perceptionintroduces its audience to these and related basic issues concerned with listening to music. It also illustrates how knowledge about music perception may ultimately lead to a broader understanding of conventional concepts regarding perception, attention and memory.
Hearing and communication present a variety of challenges to the nervous system. To be heard and understood, a communication signal must be transformed from a time-varying acoustic waveform to a perceptual representation to an even more abstract representation that integrates memory stores with semantic/referential information. Finally, this complex, abstract representation must be interpreted to form categorical decisions that guide behavior. Did I hear the stimulus? From where and whom did it come? What does it tell me? How can I use this information to plan an action? All of these issues and questions underlie auditory cognition. Since the early 1990s, there has been a re-birth of studies that test the neural correlates of auditory cognition with a unique emphasis on the use of awake, behaving animals as model. Continuing today, how and where in the brain neural correlates of auditory cognition are formed is an intensive and active area of research. Importantly, our understanding of the role that the cortex plays in hearing has the potential to impact the next generation of cochlear- and brainstem-auditory implants and consequently help those with hearing impairments. Thus, it is timely to produce a volume that brings together this exciting literature on the neural correlates of auditory cognition. This volume compliments and extends many recent SHAR volumes such as Sound Source Localization (2005) Auditory Perception of Sound Sources (2007), and Human Auditory Cortex (2010). For example, in many of these volumes, similar issues are discussed such as auditory-object identification and perception with different emphases: in Auditory Perception of Sound Sources, authors discuss the underlying psychophysics/behavior, whereas in the Human Auditory Cortex, fMRI data are presented. The unique contribution of the proposed volume is that the authors will integrate both of these factors to highlight the neural correlates of cognition/behavior. Moreover, unlike other these other volumes, the neurophysiological data will emphasize the exquisite spatial and temporal resolution of single-neuron [as opposed to more coarse fMRI or MEG data] responses in order to reveal the elegant representations and computations used by the nervous system.
Exposure to loud noise continues to be the largest cause of hearing loss in the adult population. The problem of NIHL impacts a number of disciplines. US standards for permissible noise exposure were originally published in 1968 and remain largely unchanged today. Indeed, permissible noise exposure for US personnel is significantly greater than that allowed in numerous other countries, including for example, Canada, China, Brazil, Mexico, and the European Union. However, there have been a number of discoveries and advances that have increased our understanding of the mechanisms of NIHL. These advances have the potential to impact how NIHL can be prevented and how our noise standards can be made more appropriate.
Synaptic Mechanisms in the Auditory System will provide a basic reference for students, clinicians, and researchers on how synapses in the auditory system function to encode acoustic signals. These mechanisms are the groundwork for all auditory processing, and understanding them requires knowledge of the microphysiology of synapses, cellular biophysics, receptor pharmacology, and an appreciation for what these synapses must do for a living, what unique jobs they carry out.
Tinnitus is a prevalent hearing disease, affecting 15% of the population, particularly hearing impaired, veterans and even young people who grow up with mp3 players and iPods. The mechanisms underlying tinnitus remain controversial. At present there is no cure for tinnitus, and treatment options are limited. Different from previous tinnitus books, including A. R. Moller's book [in press at Springer], which typically have a strong clinical flavor, the present volume focuses on neural mechanisms of tinnitus and its behavioral consequences. The proposed book starts with a general summary of the field and a short introduction on the selection and content of the remaining chapters. Chapter 2 overviews tinnitus prevalence and etiologies to set the tone for significance and complexity of this neurological disorder spectrum. Chapters 3-8 cover neuroscience of tinnitus in animal models from molecular mechanisms to cortical manifestation. Chapters 9-12 cover human brain responses to tinnitus and it clinical management.