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.

In the Occupational Safety and Health Act of 1970, Congress declared that its purpose was to assure, so far as possible, safe and healthful working conditions for every working man and woman and to preserve our human resources. In this Act, the National Institute for Occupational Safety and Health (NIOSH) is charged with recommending occupational safety and health standards and describing exposure concentrations that are safe for various periods of employment-including but not limited to concentrations at which no worker will suffer diminished health, functional capacity, or life expectancy as a result of his or her work experience. By means of criteria documents, NIOSH communicates these recommended standards to regulatory agencies (including the Occupational Safety and Health Administration [OSHA]) and to others in the occupational safety and health community. Criteria documents provide the scientific basis for new occupational safety and health standards. These documents generally contain a critical review of the scientific and technical information available on the prevalence of hazards, the existence of safety and health risks, and the adequacy of control methods. In addition to transmitting these documents to the Department of Labor, NIOSH also distributes them to health professionals in academic institutions, industry, organized labor, public interest groups, and other government agencies. In 1972, NIOSH published Criteria for a Recommended Standard: Occupational Exposure to Noise, which provided the basis for a recommended standard to reduce the risk of developing permanent hearing loss as a result of occupational noise exposure [NIOSH 1972]. NIOSH has now evaluated the latest scientific information and has revised some of its previous recommendations. The 1998 recommendations go beyond attempting to conserve hearing by focusing on preventing occupational noise-induced hearing loss (NIHL). This criteria document reevaluates and reaffirms the recommended exposure limit (REL) for occupational noise exposure established by the National Institute for Occupational Safety and Health (NIOSH) in 1972. The REL is 85 decibels, A-weighted, as an 8-hr time-weighted average (85 dBA as an 8-hr TWA). Exposures at or above this level are hazardous. By incorporating the 4000-Hz audiometric frequency into the definition of hearing impairment in the risk assessment, NIOSH has found an 8% excess risk of developing occupational noise-induced hearing loss (NIHL) during a 40-year lifetime exposure at the 85-dBA REL. NIOSH has also found that scientific evidence supports the use of a 3-dB exchange rate for the calculation of TWA exposures to noise. The recommendations in this document go beyond attempts to conserve hearing by focusing on prevention of occupational NIHL. For workers whose noise exposures equal or exceed 85 dBA, NIOSH recommends a hearing loss prevention program (HLPP) that includes exposure assessment, engineering and administrative controls, proper use of hearing protectors, audiometric evaluation, education and motivation, recordkeeping, and program audits and evaluations. Audiometric evaluation is an important component of an HLPP. To provide early identification of workers with increasing hearing loss, NIOSH has revised the criterion for significant threshold shift to an increase of 15 dB in the hearing threshold level (HTL) at 500, 1000, 2000, 3000, 4000, or 6000 Hz in either ear, as determined by two consecutive tests. To permit timely intervention and prevent further hearing losses in workers whose HTLs have increased because of occupational noise exposure, NIOSH no longer recommends age correction on individual audiograms.

The Institute of Medicine carried out a study mandated by Congress and sponsored by the Department of Veterans Affairs to provide an assessment of several issues related to noise-induced hearing loss and tinnitus associated with service in the Armed Forces since World War II. The resulting book, Noise and Military Service: Implications for Hearing Loss and Tinnitus, presents findings on the presence of hazardous noise in military settings, levels of noise exposure necessary to cause hearing loss or tinnitus, risk factors for noise-induced hearing loss and tinnitus, the timing of the effects of noise exposure on hearing, and the adequacy of military hearing conservation programs and audiometric testing. The book stresses the importance of conducting hearing tests (audiograms) at the beginning and end of military service for all military personnel and recommends several steps aimed at improving the military services' prevention of and surveillance for hearing loss and tinnitus. The book also identifies research needs, emphasizing topics specifically related to military service.

Topics covered include fundamentals of sound, vibration and hearing, elements of a hearing conservation program, noise interference and annoyance, regulations, standards and laws.

The auditory system is one of the finest structures in the human body. Although its anatomical structure is so small compared to other organs, without it, it would greatly affect a person’s basic life. Hearing loss, also known as hearing impairment, is a partial or total inability to hear. When people communicate with others, listening is always the first step. That is why Helen Keller once said, “Blindness separates people from things; deafness separates people from people.” To avoid the “epidemic” of hearing loss in the near future, it is necessary to promote early screening, change public attitudes toward noise, and wear hearing aids appropriately. Based on the contributions of many authors, whom I sincerely respect, this book incorporates updated developments as well as future perspectives in the ever-expanding field of hearing loss. This book can also serve as a reference for persons who are involved in this field whether they are clinicians, researchers, or patients.

People are increasingly concerned about potential environmental health hazards and often ask their physicians questions such as: "Is the tap water safe to drink?" "Is it safe to live near power lines?" Unfortunately, physicians often lack the information and training related to environmental health risks needed to answer such questions. This book discusses six competency based learning objectives for all medical school students, discusses the relevance of environmental health to specific courses and clerkships, and demonstrates how to integrate environmental health into the curriculum through published case studies, some of which are included in one of the book's three appendices. Also included is a guide on where to obtain additional information for treatment, referral, and follow-up for diseases with possible environmental and/or occupational origins.

Written in clear and accessible language, Occupational Hearing Loss provides a comprehensive overview of the hazards of occupational noise exposure, causes of hearing loss, testing of hearing, criteria to distinguish occupational hearing loss, and more. This third edition features expanded discussion of topics such as autoimmune inner ear disease and diagnosing occupational hearing loss. It includes new chapters on auditory evoked potentials, sudden sensorineural hearing loss, malignancies of the ear, otologic complications of scuba diving, and hearing in dogs. This text also contains updated and revised material on auditory processing disorders, systemic causes of hearing loss, and more.

In our industrialized world, we are surrounded by occupational, recreational, and environmental noise. Very loud noise damages the inner-ear receptors and results in hearing loss, subsequent problems with communication in the presence of background noise, and, potentially, social isolation. There is much less public knowledge about the noise exposure that produces only temporary hearing loss but that in the long term results in hearing problems due to the damage of high-threshold auditory nerve fibers. Early exposures of this kind, such as in neonatal intensive care units, manifest themselves at a later age, sometimes as hearing loss but more often as an auditory processing disorder. There is even less awareness about changes in the auditory brain caused by repetitive daily exposure to the same type of low-level occupational or musical sound. This low-level, but continuous, environmental noise exposure is well known to affect speech understanding, produce non-auditory problems ranging from annoyance and depression to hypertension, and to cause cognitive difficulties. Additionally, internal noise, such as tinnitus, has effects on the brain similar to low-level external noise.Noise and the Brain discusses and provides a synthesis of hte underlying brain mechanisms as well as potential ways to prvent or alleviate these aberrant brain changes caused by noise exposure. - Authored by one of the preeminent leaders in the field of hearing research - Emphasizes direct and indirect changes in brain function as a result of noise exposure - Provides a comprehensive and evidence-based approach - Addresses both developmental and adult plasticity - Includes coverage of epidemiology, etiology, and genetics of hearing problems; effects of non-damaging sound on both the developing and adult brain; non-auditory effects of noise; noise and the aging brain; and more

The collection of systems represented in Sourcebook of genomic programs, although this work is certainly well Models for Biomedical Research is an effort to re?ect the represented and indexed. diversity and utility of models that are used in biomedicine. Some models have been omitted due to page limitations That utility is based on the consideration that observations and we have encouraged the authors to use tables and made in particular organisms will provide insight into the ? gures to make comparisons of models so that observations workings of other, more complex, systems. Even the cell not available in primary publications can become useful to cycle in the simple yeast cell has similarities to that in the reader. humans and regulation with similar proteins occurs. We thank Richard Lansing and the staff at Humana for Some models have the advantage that the reproductive, guidance through the publication process. mitotic, development or aging cycles are rapid compared As this book was entering production, we learned of the with those in humans; others are utilized because individual loss of Tom Lanigan, Sr. Tom was a leader and innovator proteins may be studied in an advantageous way and that in scienti?c publishing and a good friend and colleague to have human homologs. Other organisms are facile to grow all in the exploratory enterprise. We dedicate this book to in laboratory settings or lend themselves to convenient analy- his memory. We will miss him greatly.