UNDERWATER NOISE OF WHALE-WATCHING BOATS AND POTENTIAL EFFECTS ON KILLER WHALES (ORCINUS ORCA), BASED ON AN ACOUSTIC IMPACT MODEL

Underwater noise of whale-watching boats was recorded in the popular killer whale-watching region of southern British Columbia and northwestern Washington State. A software sound propagation and impact assessment model was applied to estimate zones around whale-watching boats where boat noise was audible to killer whales, where it interfered with their communication, where it caused behavioral avoidance, and where it possibly caused hearing loss. Boat source levels ranged from 145 to 169 dB re 1 μPa @ 1 m, increasing with speed. The noise of fast boats was modeled to be audible to killer whales over 16 km, to mask killer whale calls over 14 km, to elicit a behavioral response over 200 m, and to cause a temporary threshold shift (TTS) in hearing of 5 dB after 30–50 min within 450 m. For boats cruising at slow speeds, the predicted ranges were 1 km for audibility and masking, 50 m for behavioral responses, and 20 m for TTS. Superposed noise levels of a number of boats circulating around or following the whales were close to the critical level assumed to cause a permanent hearing loss over prolonged exposure. These data should be useful in developing whale-watching regulations. This study also gave lower estimates of killer whale call source levels of 105–124 dB re 1 μPa.     

Building the mammalian cochlea — an overview

The mammalian cochlea is a highly intricate organ responsible for hearing. Numerous specialized cell types residing in the cochlear participate in processing and relaying sound information to the brain. In general, cells in the cochlea are divided into three major types: sensory, neural, and non-sensory. Sensory cells are a group of cells in the organ of Corti consisting of hair cells and supporting cells. Sensory hair cells play a primary role in detecting and processing sound in the form of vibrations. Neural cells are the neurons and glia in the spiral (cochlear) ganglion that relay the processed sound signals in the form of a neurotransmitter to the brain. Other non-sensory cells include all other cell types providing architectural and functional support. Building a functional cochlea requires tightly orchestrated, spatial and temporal regulation of gene expressions. Disruption of the normal gene expression patterns can cause developmental failure of the organ, which can lead to permanent hearing loss. Thus, comprehensive understanding of genes contributing to cochlear development is crucial for elucidating the pathological mechanisms of hearing loss. This article is intended to provide an overview of mammalian cochlear development, focusing on genes involved in its early patterning.     

White Noise Masks Some Temporal Parameters of the Auditory Localization of Radially Moving Targets

The temporal parameters of the perception of radially moving sound sources partly masked with broadband internalized noise at an intensity of 40, 46, or 52 dB above the hearing threshold have been studied. The threshold of sound duration necessary for identifying the direction of movement of the sound source (75% correct answers) increases from 135 ms in silence to 285 ms at all intensities of continuous noise studied. The minimum duration of the stimulus beginning with which a subsequent increase in duration does not increase the number of correct responses is the same (385 ms) under all conditions of stimulus presentation. Broadband noise of any intensity increases the time of response to stimuli in the range of durations studied. At a noise of 52 dB, which is close to the threshold of full masking, the reaction time is not increased significantly compared to its estimation at a noise of 46 dB. The minimum duration of the stimulus has proved to be the stablest temporal parameter of the perception of movement of a sound source. Changes in the temporal parameters of sound perception at noise levels close to the threshold of full masking are discussed.     

Noise and the classical musician.

OBJECTIVES--To test the hypothesis that noise exposure may cause hearing loss in classical musicians. DESIGN--Comparison of hearing levels between two risk groups identified during the study by measuring sound levels. SETTING--Symphony orchestra and occupational health department in the west Midlands. MAIN OUTCOME MEASURES--Hearing level as measured by clinical pure tone audiometry. RESULTS--Trumpet and piccolo players received a noise dose of 160% and 124%, respectively, over mean levels during part of the study. Comparison of the hearing levels of 18 woodwind and brass musicians with 18 string musicians matched for age and sex did not show a significant difference in hearing, the mean difference in the hearing levels at the high (2, 4, and 8 KHz) audiometric frequencies being 1.02 dB (95% confidence interval -2.39 to 4.43). CONCLUSIONS--This study showed that there is a potential for occupational hearing loss in classical orchestral musicians.     

Photobiomodulation using low‐level 808 nm diode laser rescues cochlear synaptopathy after acoustic overexposure in rat

A certain degree of noise can cause hearing problems without a permanent change in the hearing threshold, which is called hidden hearing loss and results from partial loss of auditory synapses. Photobiomodulation (PBM) enhances neural growth and connections in the peripheral nervous systems. In this study, we assessed whether PBM could rescue cochlear synaptopathy after acoustic overexposure in rat. PBM was performed for 7 days after noise exposure. The auditory brainstem responses (ABRs) were acquired before and after noise exposure using a tone and a paired‐click stimulus. Auditory response to paired click sound with short time interval was performed to evaluate auditory temporal processing ability. In the result, hearing threshold recovered 2 weeks after noise exposure in both groups. Peak wave 1 amplitude of the ABR and ABR recovery threshold did not recover in the noise only group, whereas it fully recovered in the noise + PBM group. The number of synaptic ribbons was significantly different in the control and noise only groups, while there was no difference between the control and noise + PBM group. These results indicate that PBM rescued peak wave 1 amplitude and maintained the auditory temporal processing ability resulting from a loss of synaptic ribbons after acoustic overexposure.     

Measuring noise

High levels of noise encountered both in leisure activities and at workplaces can be somewhat annoying, but they can also cause hearing damage. In order to lessen these risks, some physical characteristics of the sound phenomenon need to be understood. The level of a sound is given in dB, a logarithmic unit in which simple addition is not available : 100 dB + 100 dB = 103 dB. The highest level of noise which can be tolerated by the human ear is considered to be 120 dB. Another component of sound characteristics is the frequency, which describes the height of a sound. The frequency is given in Hz, the human hearing field is comprised in the range of 20 to 20,000 Hz. Regarding the sensitivity of the ear, depending on the frequency, acusticians use a weighed dB, called dB(A), which takes into account a lower risk to hearing below 500 Hz and above 6 kHz. They also integrate the energy measured during a period of time to take the fluctuation of usual noise levels into account. So that currently, the levels of noise are often given in LAeq (equivalent to the level of continuous noise given in dBA). For moderate levels of noise, another weighted filter is used in sound level meters : the C curve, because low frequencies, although they are less dangerous for the ear, are more disturbing. In every day life, we sometimes have noise levels reaching 100 dB, and even 120 dB (fire alarms). Amplified music can reach 110 dBA, but a French regulation limits the output of PCPs (Walkmans) to 100 dB and the levels in concerts and discotheques to 105 dBA. At the workplace, the maximum level of noise allowed by French Law is 90 dBA for an 8 hour exposure, and 140 dB for peaks. In order to improve the protection of all workers in the EC, a recent European Directive will decrease the maximum level to 87 dBA before March 2006.     

Hearing in laboratory animals: strain differences and nonauditory effects of noise

Hearing in laboratory animals is a topic that traditionally has been the domain of the auditory researcher. However, hearing loss and exposure to various environmental sounds can lead to changes in multiple organ systems, making what laboratory animals hear of consequence for researchers beyond those solely interested in hearing. For example, several inbred mouse strains commonly used in biomedical research (e.g., C57BL/6, DBA/2, and BALB/c) experience a genetically determined, progressive hearing loss that can lead to secondary changes in systems ranging from brain neurochemistry to social behavior. Both researchers and laboratory animal facility personnel should be aware of both strain and species differences in hearing in order to minimize potentially confounding variables in their research and to aid in the interpretation of data. Independent of genetic differences, acoustic noise levels in laboratory animal facilities can have considerable effects on the inhabitants. A large body of literature describes the nonauditory impact of noise on the biology and behavior of various strains and species of laboratory animals. The broad systemic effects of noise exposure include changes in endocrine and cardiovascular function, sleep-wake cycle disturbances, seizure susceptibility, and an array of behavioral changes. These changes are determined partly by species and strain; partly by noise intensity level, duration, predictability, and other characteristics of the sound; and partly by animal history and exposure context. This article reviews some of the basic strain and species differences in hearing and outlines how the acoustic environment affects different mammals.     

Acoustic communication in two freshwater gobies: the relationship between ambient noise,hearing thresholds and sound spectrum

Two freshwater gobies Padogobius martensii and Gobius nigricans live in shallow (5-70 cm) stony streams, and males of both species produce courtship sounds. A previous study demonstrated high noise levels near waterfalls, a quiet window in the noise around 100 Hz at noisy locations, and extremely short-range propagation of noise and goby signals. To investigate the relationship of this acoustic environment to communication, we determined audiograms for both species and measured parameters of courtship sounds produced in the streams. We also deflated the swimbladder in P. martensii to determine its effect on frequency utilization in sound production and hearing. Both species are maximally sensitive at 100 Hz and produce low-frequency sounds with main energy from 70 to 100-150 Hz. Swimbladder deflation does not affect auditory threshold or dominant frequency of courtship sounds and has no or minor effects on sound amplitude. Therefore, both species utilize frequencies for hearing and sound production that fall within the low-frequency quiet region, and the equivalent relationship between auditory sensitivity and maximum ambient noise levels in both species further suggests that ambient noise shapes hearing sensitivity.     

MRI gradient coil cylinder sound field simulation and measurement

High-field, high-speed Magnetic Resonance Imaging (MRI) generates high sound levels within and nearby the scanner. The mechanism and process that produces the gradient magnetic field (a cylindrical electro-magnet, called the gradient coil cylinder, which produces a spatially and temporally varying magnetic field inside a static background magnetic field) is the primary source of this noise. This noise can cause difficulties in verbal communication in and around the scanner, heightened patient anxiety, temporary hearing loss and possible permanent hearing impairment for health care workers and patients. In order to effectively suppress the sound radiation from the gradient coil cylinder the sound field within and nearby the gradient coil needs to be characterized This characterization may be made using an analytical solution of the sound pressure field, computational simulation, measurement analysis or some combination of these three methods. This paper presents the computational simulation and measurement results of a study of the sound radiation from a head and neck gradient coil cylinder within a 4 Tesla MRI whole body scanner. The measurement results for the sound pressure level distribution along the centerline of the gradient coil cylinder are presented. The sound pressure distributions predicted from Finite Element Analysis of the gradient coil movement during operation and subsequent Boundary Element Analysis of the sound field generated are also presented. A comparison of the measured results and the predicted results shows close agreement. Because of the extremely complex nature of the analytical solution for the gradient coil cylinder, a treatment of the analytical solution and comparison to the computational results for a simple cylinder vibrating in a purely radial direction are also presented and also show close agreement between the two methods thus validating the computational approach used with the more complex gradient coil cylinder.     

Impulse Noise and Neurosensory Hearing Loss—Relationship to Small Arms Fire

The problems of noise are not limited to the simple annoyance of an individual. Noise can produce a permanent hearing handicap. Many everyday activities and hobbies are associated with hazardous exposure to noise. The hunter and the sport shooter are potential subjects of severe and unresolvable hearing loss.Noise-induced hearing loss develops insidiously. The means of prevention are far more simple than is correction of the loss. Wearing ear protectors, plugs or earmuffs, is advisable during exposure to hazardous noise.     

噪声所致听力损失现象的物种差异及可能生理机制研究进展

噪声广泛存在于人和动物的生活环境中,从无脊椎动物到哺乳动物乃至人类,都会受到噪声的负面影响.强烈的噪声会损伤听觉系统的结构和功能,引起噪声性听力损失(noise-induced hearing loss,NIHL).本文对噪声性听力损失的类型、影响因素、噪声所致不同程度听力损失形成的可能机制进行了总结,发现NIHL主要与突触结构肿胀、谷氨酸引起的可逆兴奋性中毒以及活性氧引起的氧化应激、细胞凋亡、带状体损伤、α激动型鸟嘌呤核苷酸结合蛋白(guanine nucleotide binding protein alpha stimulating,GNAS)基因的mRNA及其上游lncRNA Sept7的表达量上调等因素有关.比较噪声暴露后不同物种听力损失情况的差异,发现鱼类和鸟类由于具有毛细胞再生能力而能够较快从听力损伤中恢复,啮齿类较容易受到噪声影响,而回声定位鲸类噪声暴露后的暂时性听觉阈移较小,非常有趣的是回声定位蝙蝠在噪声高强度暴露后未表现出暂时性听觉阈移的现象.上述结论提示,对不同物种的比较生理研究可深入揭示NIHL机制,并为听力保护以及噪声所致的听力损伤后修复等提供理论参考.     

Acoustic overstimulation activates 5'-AMP-activated protein kinase through a temporary decrease in ATP level in the cochlear spiral ligament prior to permanent hearing loss in mice

Inner ear disorders are known to be elicited by mitochondrial dysfunction, which decreases the ATP level in the inner ear. 5′-AMP-activated protein kinase (AMPK) is a serine/threonine kinase activated by metabolic stress and by an increase in the AMP/ATP ratio. To elucidate the involvement of AMPK-derived signals in noise-induced hearing loss, we investigated whether in vivo acoustic overstimulation would activate AMPK in the cochlea of mice. Std-ddY mice were exposed to 8 kHz octave band noise at a 90-, 110- or 120-dB sound pressure level (SPL) for 2 h. Exposure to the noise at 110 or 120 dB SPL produced outer hair cell death in the organ of Corti and permanent hearing loss. Exposure to the noise at 120-dB SPL elevated the level of the phospho-AMPK α-subunit (p-AMPKα), without affecting the protein level of this subunit, immediately and at 12-h post-exposure in the lateral wall structures including the spiral ligament and stria vascularis. In the hair cells and spiral ganglion cells, no marked change in the level of p-AMPKα was observed at any time post-exposure. The level of phospho-c-Jun N-terminal kinase (p-JNK) was increased in the lateral wall structures at 2- to 4-h post-exposure at 120 dB SPL. Noise exposure significantly, but temporarily, decreased the ATP level in the spiral ligament, in an SPL-dependent manner at 110 dB and above. Likewise, elevation of p-AMPKα and p-JNK levels was also observed in the lateral wall structures post-exposure to noise at an SPL of 110 dB and above. Taken together, our data suggest that AMPK and JNK were activated by ATP depletion in the cochlear spiral ligament prior to permanent hearing loss induced by in vivo acoustic overstimulation.     

The Survival Attractor in the Sensory Functions: The Example of Hearing

High noise levels may have an adverse effect on the normal cochlea function and lead to significant hearing loss. Clinically, exposure to high intensity impulse noise produces a wide range of audiometric effects which may result in long term or even irreversible symptoms. Nevertheless, there is sometimes a spontaneous rebound recovery of the auditory function. This phenomenon was previously studied in the vision, another sensory function. It was called the visual survival attractor. In view of the importance that the sensory organs have for the brain, and in particular in its function of recognising and dealing with its environment, it was interesting to know whether this survival attractor concept already described for vision occurs more generally in all the sensory functions. With this in mind we present here the results of a new study, this time on hearing. This study was carried out on guinea pigs subjected to a pulsed acoustic trauma simulating the sound of a gun going off. Auditory function was explored using electrocochleography and two types of investigation were carried out. At first the change in hearing loss was studied in relation to frequencies varying between 2 and 24 kHz by calculating the difference, at each frequency, between the compound action potential thresholds measured before and then 20 mn, 24 h and 7 days after the acoustic trauma. On the other hand, the change in compound action potential amplitude was determined by varying the stimulating sound level from the auditory threshold up to 90 dB. This change was also recorded at the same time intervals as the investigation of hearing loss. In both the analysis of changes to hearing loss and in the investigation of variations in compound action potential, the results of the electrocochleographic investigations after acoustic trauma confirm the presence of a butterfly catastrophe type reaction process, that is positive evidence of a hearing survival attractor.     

Effects of noise on inner ear

The effects of noise on health depend both on individual factors and characteristics of sound exposure. In case of acoustic trauma, reversible or irreversible lesions of inner ear components are possible. Most often there is immediately an acute tinnitus and hearing loss. Audiometric tests demonstrate hearing loss on the high frequency, generally focused on 4 kHz. Immediate treatment is recommended even there is no currently indicator of the ability to restore hearing. New perspectives on treatment are directed to local treatment and/or using new procedure as antioxidative treatment. Occupational and leisure are the two conditions in which chronic exposure to noise is found. Detection and prevention of noise-induced hearing loss is easier in case of industrial workers than in case of noise exposition for musicians and other sounds and stage technicians or concert managers, and of course non-professional with exposure to amplified music.     

Anti-apoptotic role of retinoic acid in the inner ear of noise-exposed mice

Exposure to loud noise can induce temporary or permanent hearing loss, and acoustic trauma is the major cause of hearing impairment in industrial nations. However, the mechanisms underlying the death of hair cells after acoustic trauma remain unclear. In addition to its involvement in cellular stress and apoptosis, the c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase family, is involved in cell survival, transformation, embryonic morphogenesis, and differentiation. JNK is primarily activated by various environmental stresses including noise, and the phenotypic result appears be to cell death. All-trans retinoic acid (ATRA) is an active metabolite of vitamin A that regulates a wide range of biological processes, including cell proliferation, differentiation, and morphogenesis. We evaluated the role of ATRA in preserving hearing in mice exposed to noise that can induce permanent hearing loss. Mice fed with ATRA before and during 3 consecutive days of noise exposure had a more preserved hearing threshold than mice fed sesame oil or saline. Histological and TUNEL staining of the cochlea showed significantly enhanced preservation of the organ of Corti, including outer hair cells and relatively low apoptotic nuclei, in mice-fed ATRA than in mice-fed sesame oil or saline. Phospho-JNK immunohistochemistry showed that ATRA inhibited the activation of JNK. These results suggest that ATRA has an anti-apoptotic effect on cochleae exposed to noise.     

Auditory evoked potential audiometry in fish

A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. First, our review compares AEP hearing thresholds to behaviorally gained thresholds. Second, baseline hearing abilities are described and compared in 111 fish species out of 51 families. Following this, studies investigating the functional significance of various accessory hearing structures (Weberian ossicles, swim bladder, otic bladders) by eliminating these morphological structures in various ways are dealt with. Furthermore, studies on the ontogenetic development of hearing are summarized. The AEP-technique was frequently used to study the effects of high sound/noise levels on hearing in particular by measuring the temporary threshold shifts after exposure to various noise types (white noise, pure tones and anthropogenic noises). In addition, the hearing thresholds were determined in the presence of noise (white, ambient, ship noise) in several studies, a phenomenon termed masking. Various ecological (e.g., temperature, cave dwelling), genetic (e.g., albinism), methodical (e.g., ototoxic drugs, threshold criteria, speaker choice) and behavioral (e.g., dominance, reproductive status) factors potentially influencing hearing were investigated. Finally, the technique was successfully utilized to study acoustic communication by comparing hearing curves with sound spectra either under quiet conditions or in the presence of noise, by analyzing the temporal resolution ability of the auditory system and the detection of temporal, spectral and amplitude characteristics of conspecific vocalizations.     

Interspecific variation in the response of fish to anthropogenic noise

1. Elevated levels of anthropogenic noise, especially those observed through boating activity, can negatively impact fish species, but it remains unclear which species are most affected and which behavioural metrics are best used in assessing fish responses to underwater noise. The effects of boat sounds on freshwater species are of particular interest because freshwater environments are less studied than the marine realm despite comparably high levels of biodiversity.
2. In the current study, we examine the behavioural responses to boat noise in two freshwater species that differ in their hypothesised response to sound inputs: the spottail shiner (Notropis hudsonius), a species with known hearing specialisations, and the bluegill sunfish (Lepomis macrochirus), a species with more generalised hearing capabilities. Fish were presented with boat noise in a laboratory setting, and their swimming, escape and foraging behaviours were assessed to examine differential responses in relation to hypothesised hearing abilities.
3. Both species showed a decrease in general swimming behaviours but an increase in erratic movements in response to boat noise, indicative of stress responses for both species. Despite the similarities in response based on swimming behaviours however, only spottail shiners exhibited true escape responses to the onset of the noise stimulus, suggesting a more extreme reaction in the species with a more refined hearing ability.
4. Taken together, these results show that freshwater fish can respond to increased levels of anthropogenic noise, but that the severity of the response may differ based on auditory structures and therefore presumed hearing ability. The differences seen between behavioural metrics used (swimming vs. escape responses) also demonstrate how care must be taken in choosing a metric when developing exposure guidelines for underwater sound exposures, as different metrics could lead to differential impact assessments.

     

Thyroid hormone-deficient period prior to the onset of hearing is associated with reduced levels of beta-tectorin protein in the tectorial membrane: implication for hearing loss

The genes for alpha- and beta-tectorin encode the major non-collagenous proteins of the tectorial membrane. Recently, a targeted deletion of the mouse alpha-tectorin gene was found to cause loss of cochlear sensitivity (). Here we describe that mRNA levels for beta-tectorin, but not alpha-tectorin, are significantly reduced in the cochlear epithelium under constant hypothyroid conditions and that levels of beta-tectorin protein in the tectorial membrane are lower. A delay in the onset of thyroid hormone supply prior to onset of hearing, recently described to result in permanent hearing defects and loss of active cochlear mechanics (), can also lead to permanently reduced beta-tectorin protein levels in the tectorial membrane. beta-Tectorin protein levels remain low in the tectorial membrane up to one year after the onset of thyroid hormone supply has been delayed until postnatal day 8 or later and are associated with an abnormally structured tectorial membrane and the loss of active cochlear function. These data indicate that a simple delay in thyroid hormone supply during a critical period of development can lead to low beta-tectorin levels in the tectorial membrane and suggest for the first time that beta-tectorin may be required for development of normal hearing.     

The inner ear morphology and hearing abilities of the Paddlefish (Polyodon spathula) and the Lake Sturgeon (Acipenser fulvescens)

Concern regarding the spread of silver carp (Hypopthalmichthys molitrix) and bighead carp (Aristichthysc nobilis) through the Illinois River has prompted the development of an Acoustic Fish Deterrent (AFD) system. The application of this technology has resulted in a need to understand the auditory physiology of fish other than the target species, in order to minimise the effect of the AFD barrier on the ecology of indigenous fish populations. To this end, both the structures involved in sound reception and the hearing abilities of the paddlefish (Polyodon spathula) and the lake sturgeon (Acipenser fulvescens) are studied here using a combination of morphological and physiological approaches, revealing that both fish are responsive to sounds ranging in frequency from 100 to 500 Hz. The lowest hearing thresholds from both species were acquired from frequencies in a bandwidth of between 200 and 300 Hz, with higher thresholds at 100 and 500 Hz. The rationale for studying hearing in P. spathula and A. fulvescens in particular, is the value placed on them by both the commercial caviar producing industry and by the recreational fisheries sector. The hearing abilities of twelve P. spathula and twelve A. fulvescens were tested in sound fields dominated by either sound pressure or particle motion, with the results showing that acipenseriform fish are responsive to the motion of water particles in a sound field, rather than the sound pressure component. In this study, we measure the intensity of the sound field required to evoke threshold responses using a pressure sensitive hydrophone, as pressure dominated sound fields are the most audible acoustic condition for specialists like H. molitrix and A. nobilis (the target species). The results of the auditory examination clearly show that P. spathula and A. fulvescens are not sensitive to sound pressure, and will therefore have a significantly higher deterrent threshold than H. molitrix and A. nobilis in a pressure dominated sound field.