Decibel Levels Research Articles

Ambient noise and gray whale Eschrichtius robustus behavior

Between 14 February and 13, April 2006, we conducted 31 recording sessions of ambient noise and behavioral sampling of gray whales within Magdalena Bay, Mexico. This breeding lagoon does not have the same Marine Protected Area status compared to the other breeding lagoons of San Ignacio and Guerrero Negro in the Mexican Pacific coast. Poorly monitored guidelines and increasing boat traffic from whale−watching tourism in this area have the potential to affect the surface behavior of these animals and increase average ambient noise levels. Relative ambient noise levelswererecordedandcomparedtoapreviousstudy[Ollervides,2001]todetermine similarities or differences in the 5−year interval between both data sets. Although results are not comparable in decibel levels, probably due to equipment calibration problems, there was a significant difference between the different regions of the bay Kruskal−Wallis (p=0.0067). Activity levels ranged from 0.005–0.196 behaviors/whale/minute. Ambient noise levels ranged from 35.70–64.32 dB Re: 1 Pa. No correlation was found between the ambient noise levels in the bay and the activity level of gray whales (correlation value=0.0126; log correlation value=0.172). Further acoustic processing is currently underway.

Hearing Screening Practices Among a National Sample of Primary Care Pediatricians

The objective of this study was to describe variations in hearing screening using a survey mailed to a national sample of primary care pediatricians prior to the 2003 American Academy of Pediatrics (AAP) hearing screening guidelines. Of the 390 primary care respondents, only 303 (78%) performed audiometry, routinely beginning at age 3 (32%), 4 (44%), or 5 (17%); 81% defined abnormal audiometry primarily as failure to hear at a specified decibel level: 15 dB hearing level (HL) (<1%), 16 to 20 dB HL (10%), 21 to 25 dB HL (23%), 26 to 30 dB HL (44%), 31 to 40 dB HL (16%), and more than 40 dB HL (6%). This study serves as a baseline for comparison with postguideline practices.

Protective effect of edaravone in inner-ear barotrauma in guinea pigs

The purpose of this study was to determine the protective effect of edaravone, a free radical scavenger, on inner-ear barotrauma (IEB) in guinea pigs, based on a hypothesis implicating free radicals in the development of IEB. One hundred and twenty-five guinea pigs were divided into a control group and a pretreatment group. After auditory brainstem response (ABR) testing, the pretreatment group received 9.0 mg/kg intraperitoneal edaravone. Animals were exposed to pressure loading and then to further ABR testing. The incidence of IEB was 62.7 per cent in the control group and 42.9 per cent in the pretreatment group (p<0.01). The distributions of threshold elevation in the control group were 37.3 per cent (for 10 dB or less), 21.3 per cent (for 20-30 dB), 18.0 per cent (for 40-60 dB) and 23.4 per cent (for 70 dB or more), and those in the pretreatment group were 57.1 per cent, 19.1 per cent, 14.3 per cent and 9.5 per cent, for the same respective decibel levels (p<0.01). These results suggest that protective treatment with edaravone can significantly reduce both the incidence of IEB and the severity of the resultant ABR threshold elevation.

Increase Patient Safety by Creating a Quieter Hospital Environment

ers, alarms, machines, telephones, voices, are considered “usual and customary”—normal to those who work there and those who watch the television show “ER.” To patients, however, the sounds of the hospital are far from normal. Depending on age, hearing acuity, medication levels, culture, and fears, these sounds are antagonistic, worsening a situation that is already difficult. Beyond difficult, however, prolonged exposure to environmental noise can increase anxiety and stress, ultimately impacting patient safety. But the good news is that it is possible to address the noise issue and create an environment for patients that is not only of better quality, but also inherently safer.

PREDICTING EMERGENCE, CHORUSING, AND OVIPOSITION OF PERIODICAL CICADAS

Periodical cicadas in the genus Magicicada have an unusual life history that includes an exceptionally long life cycle and a massive, synchronized emergence. Distributions in woodland habitat are extremely patchy, and an unresolved problem is how the patchiness is generated and maintained. We undertook a study in Princeton, New Jersey, USA, to determine if habitat factors such as tree height, distance to the nearest neighbor, and amount of foliage influence distributions of nymphal emergences, centers of chorusing aggregations, and oviposition sites. Emerging nymphs were counted, chorus centers were identified by measuring decibel levels of their songs, and oviposition was estimated from the foliage "flags" that are produced by trees in response to the damage caused by egg-laying. All three distributions were mapped on 50 trees in a human-managed area of 75 x 130 m. We were unable to identify habitat features that were associated with the distribution of emergences, except that tulip trees (Liriodendron) had significantly fewer emergences than two other genera, ash (Fraxinus) and beech (Fagus). Using multiple linear regression analysis, we found that the distribution of emergences was the best predictor of the distribution of chorus centers and oviposition sites. In an analysis of ash trees alone, tree height and spacing, in addition to cicada emergences, predicted chorus centers and oviposition incidence. Thus the distribution of the offspring generation (oviposition) is shown to be similar to the parental generation (emergence). We suggest that their stability is maintained across generations by extremely low dispersal and mutual attraction. Aggregations may be thought of as self-perpetuating, randomly distributed assemblages, initially established through the interaction of factors, including successful exploitation of underground resources, and avoidance of fungal disease and aboveground predation in the development of high-density mating aggregations.

Improvement in hearing after chiropractic care: a case series

BackgroundThe first chiropractic adjustment given in 1895 was reported to have cured deafness. This study examined the effects of a single, initial chiropractic visit on the central nervous system by documenting clinical changes of audiometry in patients after chiropractic care.Case presentationFifteen patients are presented (9 male, 6 female) with a mean age of 54.3 (range 34–71). A Welch Allyn AudioScope 3 was used to screen frequencies of 1000, 2000, 4000 and 500 Hz respectively at three standard decibel levels 20 decibels (dB), 25 dB and 40 dB, respectively, before and immediately after the first chiropractic intervention. Several criteria were used to determine hearing impairment. Ventry & Weinstein criteria of missing one or more tones in either ear at 40 dB and Speech-frequency criteria of missing one or more tones in either ear at 25 dB.All patients were classified as hearing impaired though greater on the right. At 40 dB using the Ventry & Weinstein criteria, 6 had hearing restored, 7 improved and 2 had no change. At 25 dB using the Speech-frequency criteria, none were restored, 11 improved, 4 had no change and 3 missed a tone.ConclusionA percentage of patients presenting to the chiropractor have a mild to moderate hearing loss, most notably in the right ear. The clinical progress documented in this report suggests that manipulation delivered to the neuromusculoskeletal system may create central plastic changes in the auditory system.

The Effect of Gender on One-Day-Old Infants' Behavior and Heart Rate Responses to Music Decibel Level

The purpose of this study was to examine gender differences among full term infants' responses to music played at a range of decibel levels. These responses were measured by physiological data (heart rate) and behavioral data (behavior state score). All subjects (N = 36) were healthy, 24-48 hours old, and had passed a hearing screening at the time of testing. Heart rate and behavior state were recorded as male (n = 18) and female (n = 18) subjects listened to alternating 3-minute periods of silence and music for 21 minutes. The music--an excerpt of an instrumental lullaby--was presented via small speakers placed on either side of each subject's head and played at three different loudness levels: 55-60 dB, 65-70 dB, and 75-80 dB. Heart rate was measured using a pulse oximeter with a Y-sensor attached to each subject's great toe, and behavior state was measured using a scale adapted from the Neonatal Behavioral Assessment Scale (Brazelton & Nugent, 1995). A two-way analysis of variance with repeated measures computed for both order and gender found no significant difference in heart rate or behavior state during the three loudness levels. Possible reasons for this lack of difference include enjoyment of the music regardless of intensity or physical inability to discriminate between the different levels.

Opening Doors for Future Clinicians: Distance Learning at Longwood Targets Students in Other Disciplines

Opening Doors for Future Clinicians: Distance Learning at Longwood Targets Students in Other Disciplines

Prospective study of inner ear radiation dose and hearing loss in head-and-neck cancer patients

To determine the relationship between the radiation dose to the inner ear and long-term hearing loss. Eligible patients included those receiving curative radiotherapy (RT) for head-and-neck cancer. After enrollment, patients underwent three-dimensional conformal RT planning and delivery (180-200 cGy/fraction) appropriate for their disease site and stage. The inner ear was contoured on axial CT planning images. Dose-volume histograms, as well as the mean and maximal dose for each structure, were calculated. Patients underwent pure tone audiometry at baseline (before treatment) and 1, 6, 12, 24, and 36 months after RT. The threshold level (the greater the value, the more hearing loss) in decibels was recorded for 250, 500, 1000, 2000, 4000, and 8000 Hz. For patients receiving predominantly unilateral RT, the contralateral ear served as the de facto control. The differences in threshold level between the ipsilateral and contralateral ears were calculated, and the temporal pattern and dose-response relation of hearing loss were analyzed using statistical methods that take into account the correlation between two ears in the same subject and repeated, sequential measurements of each subject. Of the 40 patients enrolled in this study, 35 qualified for analysis. Four patients who received concurrent chemotherapy and RT were analyzed separately. The 31 unilaterally treated patients received a median dose of 47.4 Gy (range, 14.1-68.8 Gy) to the ipsilateral inner ear and 4.2 Gy (range, 0.5-31.3 Gy) to the contralateral inner ear. Hearing loss was associated with the radiation dose received by the inner ear (loss of 210dB was observed in ears receiving >/=45 Gy) and was most appreciable in the higher frequencies (>/=2000 Hz). For a 60-year-old patient with no previous hearing loss in either ear, after receiving 45 Gy, the ipsilateral ear, according to our clinical model, would have a 19.3-dB (95% confidence interval [CI], 15.5-23.0) and 5.4-dB (95% CI, 3.5-7.5) hearing decrement compared with the contralateral ear for 8000 Hz and 1000 Hz, respectively. Age and an initial hearing difference within an ear pair also affected hearing loss. The baseline hearing threshold was inversely related to radiation-induced hearing loss. The degree of hearing loss was dependent on the frequency tested, age, baseline hearing, and baseline difference in hearing between a patient's two ears. High-frequency (>/=2000 Hz) hearing acuity worsens significantly after RT in a dose-dependent fashion. A larger number of patients needs to be studied to validate these results. This knowledge can be applied to create guidelines regarding future dose limits to the auditory apparatus for patients undergoing head-and-neck RT.

Visual and hearing impairment in elderly patients hospitalized for rehabilitation following hip fracture

In a prospective study, we assessed the prevalence and significance of visual and hearing impairment in 896 patients who were hospitalized for rehabilitation following hip fracture. Visual impairment was defined as visual acuity equal to worse than 6/60 in the better of the two eyes. Hearing impairment was defined as mean decibel level equal to or higher than 60 in the better of the two ears. Visual impairment was found in 210 patients (23.4%) and hearing impairment was found in 231 patients (25.8%). Simultaneous visual and hearing impairment was seen in 72 patients (8%). In univariate analysis, the absolute efficacy of rehabilitation was significantly lower in patients with visual impairment compared to those without (p = 0.00001) and in patients with hearing impairment compared to those without (p = 0.002). However, in multivariate analysis, visual, but not hearing, impairment was found to be independently associated with the absolute efficacy of rehabilitation (p = 0.001). In light of these results, we propose that in the first phase of rehabilitation, patients' visual acuity needs to be optimized.

Qualificação e quantificação da exposição sonora ambiental em uma unidade de terapia intensiva geral

Os níveis de ruído hospitalares encontram-se excessivamente elevados, especialmente no ambiente de UTI, em decorrência dos inúmeros alarmes e equipamentos, além da conversação da própria equipe hospitalar. Diante disso, esse ambiente, que deveria ser silencioso e tranqüilo, torna-se ruidoso, transformando-se em um grande fator de estresse e podendo gerar distúrbios fisiológicos e psicológicos tanto nos pacientes como nos funcionários dessa unidade. OBJETIVO: O objetivo deste estudo foi verificar o nível de pressão sonora equivalente em uma UTI geral, procurando estabelecer o período de maior exposição e comparando os resultados com as recomendações nacionais e internacionais. FORMA DE ESTUDO: Estudo observacional. MATERIAL E MÉTODO: Medição do ruído ambiental da UTI do Hospital São Paulo através do analisador de ruído modelo 2260 (Brüel &amp; Kjaer), em período total de 6.000 minutos e aferições a cada 27 segundos, configurado da seguinte forma: tempo de resposta rápido (Fast), medindo em decibel o nível de pressão sonora e usando a ponderação em freqüência A, de setembro de 2001 a junho de 2002 e sem o conhecimento dos funcionários do setor. RESULTADOS: O nível de pressão sonora equivalente (Leq) apresentou média de 65,36 dB(A) variando de 62,9 a 69,3 dB(A). Durante o período diurno a média do Leq foi de 65,23 dB(A) e para o período noturno, 63,89 dB(A). O L FMax encontrado foi de 108,4 dB(A) e o L FMin de 40 dB(A). CONCLUSÕES: O nível de ruído encontrado nessa UTI está acima do recomendado pela literatura em todos os períodos analisados. Dessa forma, as fontes produtoras de ruído excessivo precisam ser melhor identificadas para que possam ser tomadas as devidas medidas para atenuação desse ruído e tornar esse ambiente um local mais silencioso, beneficiando a função laborativa dos profissionais e a recuperação dos pacientes.

Excessive exposure of sick neonates to sound during transport

Objective: To determine the levels of sound to which infants are exposed during routine transport by ambulance, aircraft, and helicopter. Design: Sound levels during 38 consecutive journeys from a regional...

Musings of a UN Special Rapporteur on Human Rights

The United Nations Commission on Human Rights (CHR) appointed its first special rapporteur in 1979 to report on abuses in Chile under the Augusto Pinochet dictatorship. This initiative estab lished an important precedent for the institution of special procedures to examine serious human rights violations in any country. In 1982, for the first time, a thematic rapporteurship was set up to examine summary and arbitrary executions. Consequently, the fifty-three member states of the CHR have taken steps toward a worldwide system for monitoring human rights. In mid-2002, there were forty-one special rapporteurs: thirty on thematic issues, eleven working in specific countries.1 My first appointment as special rapporteur for Burundi lasted from 1995 to 1999. In December 2000, I began a second mandate for Myanmar, a position I continue to hold.2 The selection process for special rapporteurs is somewhat in scrutable, perhaps even byzantine. It is entirely controlled by the chair of the CHR. Through direct consultations with the members of the bureau,3 the chair appoints specialists. The overall quality of appointees thus depends largely on the courage, insight, and negotiating skills of the chair. It does not suffice to want to be a special rapporteur, much less to nominate oneself, nor does having a particular interest in a given country or theme carry much weight. Vacancies arise when the CHR, which authorizes and renews mandates, proposes new missions or when someone resigns. Country-specific and thematic mandates are reviewed annually. In April 1999, the commission instituted a term limit of six years for ex perts. It is extremely unlikely to assign special rapporteurs who do not have at least the acquiescence of their own governments, although some candidates may not enjoy enthusiastic support from their home coun tries. Many civil society organizations, at higher decibel levels since the CHR's fifty-eighth session in spring 2002, have criticized the growing

Nicotine and ethanol enhancements of acoustic startle reflex are mediated in part by dopamine in C57BL/6J mice

Nicotine has been shown to have additive as well as antagonistic effects on behavior stimulated by ethanol. Here, we examine the effects of nicotine, ethanol, and the coadministration of each drug on acoustic startle responding in C57BL/6J mice. Mice were tested at a range of decibel levels (80–115 dB, 5 dB increments), with administration of 0.031, 0.062, 0.125, and 0.25 mg/kg nicotine or 0.5, 1.0, 1.5, and 2.0 g/kg ethanol. Nicotine and ethanol each caused an increase in the acoustic startle response at the highest and lowest doses tested, respectively. Mecamylamine, a nicotinic receptor antagonist, administered in combination with nicotine or ethanol attenuated these increases in acoustic startle responding. Nicotine and ethanol, administered together, did not produce greater enhancement of startle than when administered alone. Haloperidol (1 mg/kg) was administered in combination with nicotine or ethanol to investigate if dopamine modulated nicotine or ethanol enhancement of acoustic startle. It was found that the increase in acoustic startle responses observed with ethanol or nicotine was attenuated by haloperidol. Thus, ethanol or nicotine may enhance the acoustic startle reflex through a common dopaminergic mechanism.

Impairment Tutorial: Hearing Impairment

Abstract A 1999 study of adults showed hearing loss was the fifth most common disability in the US population, and almost 50% of workers in carpentry, plumbing, and mining had hearing impairment. Determining hearing impairment according to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, Section 11.2a, Criteria for Rating Impairment Due to Hearing Loss, is straightforward, if limited. Examiners should be aware that hearing can be temporarily impaired by recent exposure to loud noise and should test only after an extended period without such exposure. Audiometers should be properly calibrated, and technicians must be appropriately trained to obtain accurate measurements. The evaluator should separately test both of the individual's ears at 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz (the representative or test frequencies) and then identify the total worst ear decibel level using the AMA Guides Table 11-1 or 11-2. The evaluator can use Tale 11-3 to convert hearing impairment to whole person loss. Tinnitus also can be rated if a hearing loss in that ear affects speech discrimination; in such instances, the tinnitus rating is limited to a 5% loss. The article includes a Hearing Impairment Rating Sheet that can be used to record data from the hearing impairment evaluation.

Psychoacoustic influences of the echoing environments of prehistoric art

Cave paintings and ancient petroglyphs around the world are typically found in echo rich locations such as caves, canyons, and rocky cliff faces. Analysis of field data shows that echo decibel levels at a large number of prehistoric art sites are higher than those at nondecorated locations. The selection of these echoing environments by the artists appears not to be a mere coincidence. This paper considers the perception of an echoed sound as a psychoacoustic event that would have been inexplicable to ancient humans. A variety of ancient legends from cultures on several continents attribute the phenomenon of echoes to supernatural beings. These legends, together with the quantitative data, strongly implicate echoing as relevant to the artists of the past. The notion that the echoes were caused by spirits within the rock would explain not only the unusual locations of prehistoric art, but also the perplexing subject matter. For example, the common theme of hoofed animal imagery could have been inspired by echoes of percussion noises perceived as hoof beats. Further systematic acoustical studies of prehistoric art sites is warranted. Conservation of the natural acoustic properties of rock art environments—a previously unrecognized need—is urged.

Voice quality after radiofrequency volumetric tissue reduction of the soft palate in habitual snorers.

To evaluate whether radiofrequency volumetric tissue reduction of the soft palate is causing voice changes as a result of velopharyngeal insufficiency in patients with heavy snoring. A prospective study of 16 habitual snorers (oxygen desaturation index, <6 in all cases) were investigated concerning nasopharyngeal competence before and, at minimum, 2 months after the procedure (mean period, 165 d). Speech evaluation was made objectively with a nasal-oral ratio meter and also was made subjectively by a trained speech-language pathologist. The patients received a mean of three Somnoplasty radiofrequency volumetric tissue reduction treatments of 1200 J each (600 J in the midline and 300 J on each side of the soft palate). Comparison between preoperative and postoperative nasal-oral ratio meter analysis of hypernasality revealed no significant change. Neither did listener judgment of hypernasality, nasal escape, or pharyngeal snort reveal any influence on velopharyngeal function by the surgical procedures. Snoring was somewhat successfully treated, as evaluated by spouses; snoring score was reduced from 8.2 +/- 2.9 to 4.1 +/- 2.5 (P <.01) on a 10-grade rating scale. Maximum nocturnal decibel levels were also reduced in 79% of the cases. Radiofrequency volumetric tissue reduction in the soft palate as a treatment for snoring did not show any significant adverse effect on nasopharyngeal function.

Gender differences among newborns on a transient otoacoustic emissions test for hearing.

The purpose of this study was to examine gender differences with regard to cochlea sensitivity as measured by the transient evoked otoacoustic emissions hearing screening procedure. During this test, a sudden burst of sound is presented at between 78 and 83 dB SPL which stimulates the entire basilar membrane. This in turn excites the outer hair cells in the cochlea and causes an echo-type response which is recorded by a microphone in a probe placed in the ear canal. This test is used to screen for peripheral hearing loss. Subjects ( N = 350) for this project were healthy, full-term newborns (38-42 weeks gestation) in the first 48 hours of life who had bilaterally passed the transient evoked otoacoustic emissions (TEOAE) screening test. Male (n = 170) and female (n = 180) infants were selected randomly from all babies born during a 3-month period who met the criteria at a large birthing hospital. Responses to TEOAE stimuli were recorded at 1.6 kHz, 2.4 kHz, 3.2 kHz, and 4.0 kHz. The responses were recorded as decibel levels indicating a signal-to-noise ratio. These decibel levels were used in a three-way ANOVA with repeated measures comparing gender, ear, and frequency level. Results indicated significant differences due to gender (female hearing more sensitive than male) and frequency (least sensitive hearing recorded at 1.6 kHz, most sensitive hearing recorded at 3.2 kHz). A significant two-way interaction indicated that differences in hearing sensitivity between genders increased as the frequency increased.

Noise labeling for consumer products

Currently, ISO 4871-1996 (Acoustics–Declaration and verification of noise emission values of machinery and equipment) uses A-weighted or spectral sound power levels as metrics of choice for noise labeling. Also included is a measure of the likely variations in levels that result from machine to machine variability, measurement to measurement variability, and site to site variability. This labeling scheme is adequate to label machinery for use in commercial or industrial settings. Here, plant engineers or audiologists, etc., can readily interpret and use data. But a two-number label using the sound power level in decibels is not optimum for conveying information to the consumer. This paper suggests an alternate form for the data. Sound power is still the physical quantity measured, and, as suggested by others, a one-number system is used. The statistical variation is included by reporting the value that will not be exceeded in 19 out of 20 measurements. But the metric reported is one that is roughly proportional to judgments of loudness, and, as such, should provide greater meaning and clarity to the user. Hopefully, with comprehensible noise labeling, the consumer will be able to include noise in his/her choice of products.

Noise and vibration control for the Los Angeles Metro Rail Construction Project

Parsons Engineering Science has been retained by the Los Angeles Metropolitan Transportation Authority as the noise and vibration consultant for construction of the 17-mile-long Metro Rail subway system for a period of more than 10 years. Throughout various construction phases, short-term and long-term noise and vibration monitoring have been conducted at sensitive receptor sites such as residences, schools, hospitals, recording studios, businesses, historic buildings, and hotels, to measure both background and construction activities. Continuous noise and vibration data are collected remotely over a computer terminal, such that levels can be monitored on a moment’s notice; our engineers can hear the actual sounds at the remote monitoring site from the office (15–20 miles away), and simultaneously receive decibel levels reported in real-time. Studies are conducted to determine the impacts of various construction activities, such as pile installation, and analyze the feasibility of various construction methodologies based on project noise and vibration compatibility criteria. Mitigation measures are developed to reduce impacts. Examples of mitigation measures included the use of noise curtain walls, noise equipment specifications, selection of construction methodologies, and various acoustical treatments for noise sources. Through the monitoring program and numerous studies, noise and vibration impacts have been successfully minimized.