kHz Notch Research Articles

The noise profile and hearing impact of commercial fiberglass reinforced plastic speed boats in Port Blair, Andaman and Nicobar Islands

Background: Hearing impairment may result from tourism-related vehicle engine noise in Port Blair, Andaman, and Nicobar Islands. Aims and Objectives: Measure noise levels and test commercial fiberglass-reinforced plastic (FRP) speedboat operators for hearing loss. Materials and Methods: Hearing loss and noise impacts were checked in a total of 145 male crew members and workers exposed to commercial FRP-speedboat outboard engine noise. 18–50-year-olds with 1–20 years of experience participated. To detect hearing loss, noise-induced hearing loss (NIHL) risk indicators that could appear as a 4 kHz noise notch and the existence of high-frequency sloping hearing loss were detected using pure tone audiometry. The level of noise exposure was measured in conjunction with a questionnaire to assess an individual’s general knowledge of the effects of noise and hearing loss. Results: A 4 kHz noise notch, some high-frequency slope hearing loss, and an overall hearing loss rate of 42.1% were found in 145 participants. Out of these, 15.9% had the most common bilateral notch. Bilateral high-frequency sloping was 10.3%, Unilateral high-frequency sloping was 4.9%, and unilateral 4 kHz notch was 11.0%. According to the questionnaire, research participants are shockingly unaware of noise-induced hearing loss. The FRP Speedboat outboard engine’s measured noise level ranged from 79.7 to 89.4 dB (A). Conclusion: The FRP Speedboat crews were at risk of hearing loss, specifically NIHL with continuous noise exposure. High frequency sloping hearing loss, mild to moderate hearing loss, and a substantial 4 kHz noise notch are found in noise-exposed employees. Awareness is needed to prevent irreversible hearing loss.

Contralateral Suppression of Transient-evoked Otoacoustic Emissions in Leisure Noise Exposed Individuals.

Leisure noise may have a significant impact on hearing thresholds and young adults are often exposed to loud music during leisure activities. This behavior puts them at risk of developing noise-induced hearing loss (NIHL). A frequent initial indication of NIHL is reduced hearing acuity at 4 kHz. The objective of the current study was to assess the role of the medial olivocochlear reflex (MOCR) in leisure noise-exposed individuals with and without a 4-kHz notch. Audiological evaluation, including pure-tone and immittance audiometry, was performed for 156 college-going, young adults between May 2019 to December 2019. All participants had averaged pure-tone audiometric thresholds within normal limits, bilaterally. Annual individual exposure to personal listening devices (PLDs) was calculated using the Noise Exposure Questionnaire. The participants were then categorized into exposed (with and without audiometric 4 kHz notch) and nonexposed groups. Transient-evoked otoacoustic emission amplitude and its contralateral suppression were measured using linear and nonlinear click stimuli to study the effect of leisure noise exposure on MOCR. A significantly reduced overall contralateral suppression effect in participants exposed to PLD usage (P = 0.01) in both linear and nonlinear modes. On the contrary, significantly increased suppression was observed in linear mode for the 4 kHz frequency band in the PLD-exposed group without an audiometric notch (P = 0.009), possibly suggesting an early biomarker of NIHL. Measuring contralateral suppression of otoacoustic emissions may be an effective tool to detect early NIHL in leisure noise-exposed individuals.

Hearing Threshold Status and Risk Estimate of Hearing Impairment among Administrative Workforce.

Background:Administrative workers working in quieter environment workplace are considered unaffected by noise-induced hearing loss (NIHL).Aim:To create a baseline data of the administrative workers so as to monitor them with prospective years of exposure with the hypothesis that workers working in the administrative jobs may not be affected by NIHL.Settings and Design:The study was conducted among men and women administrative workers working in an office in Ahmedabad city, India. The design of the study was prospective cross-sectional study.Materials and Methods:In all, 64 men and 33 women administrative workers were recruited. Pure tone air conduction (AC) and unmasked bone conduction (BC) audiometry of both ears was performed. Pure tone averages (PTAs) and air-bone gap (ABG) were calculated. Excess risk of hearing impairment was estimated using five model equations.Statistical Analysis:Descriptive statistics was used for analysis. For calculation of excess risk of hearing impairment, models in online calculator were used.Results:AC for men depicted 4 and 6 kHz notch, whereas 6 kHz for women, for both ears. Around three-fourth men and nine-tenth women recorded hearing threshold <25 dB (A) for PTA0.5-1-2-4. ABG was <15 dB at all frequencies except 6 kHz, for both groups. Highest values of average estimated excess risk were 4.89% and 1.21% for men and women, respectively. Estimated excess risk ranged up to 1% for 50%–77% men and 82%–91% women.Conclusion:Administrative workers are minimally risked of developing NIHL; however, with progressive age, hearing ability may deteriorate.

Occupational noise exposure, hearing loss, and notched audiograms in the HUNT Nord-Trøndelag hearing loss study, 1996-1998.

Objectives/HypothesisTo study the prevalence and usefulness of audiometric notches in the diagnosis of noise‐induced hearing loss (NIHL).Study DesignAudiograms and data on noise exposure from 23,297 men and 26,477 women, aged 20 to 101 years, from the Nord‐Trøndelag Hearing Loss Study, 1996–1998.MethodsThe prevalence of four types of audiometric notches (Coles, Hoffman, Wilson) and 4 kHz notch were computed in relation to occupational noise exposure, age, sex, and report of recurrent ear infections.ResultsThe prevalence of notches in the 3 to 6 kHz range (Wilson, Hoffman, and Coles) ranged from 50% to 60% in subjects without occupational noise exposure, and 60% to 70% in the most occupationally noise‐exposed men. The differences were statistically significant only for bilateral notches. For 4 kHz notches, the prevalence varied from 25% in occupationally nonexposed to 35% in the most occupationally exposed men, and the differences were statistically significant for both bilateral and unilateral notches. For women, the prevalence of notches was lower than in men, especially for 4 kHz notches, and the differences between occupationally noise exposed and nonexposed were smaller. Recreational exposure to high music was not associated with notched audiograms.ConclusionsThe detection of bilateral notches and unilateral 4 kHz notches is of some value in diagnosing NIHL, especially in men.Level of Evidence4 Laryngoscope, 127:1442–1450, 2017

The prevalence of notched audiograms in a cross-sectional study of 12,055 railway workers.

Objective:Noise-induced hearing loss (NIHL) is one of the most reported occupational diseases internationally. The occurrence of audiometric notches is emphasized in both American and European guidelines for the diagnosis of NIHL. The aim of this study was to describe the prevalence of notched audiograms among railway personnel with and without noise exposure to better assess the usefulness of such notches in the diagnosis of NIHL.Design:The most recent audiogram from 1994 to 2011 of a total of 12,055 railway workers, age 20 to 65 years, was obtained from the medical records of the occupational health service of the Norwegian State Railways (NSB). The prevalences of three types of notched audiograms, Coles notch, notch index, and 4 kHz notch, were computed, in relation to age, sex, and occupational noise exposure.Results:Coles notch in either ear was found in 63% of the male railway maintenance workers, exposed to noise levels of 75 to 90 dB(A), compared with 53% of the non-noise exposed (<70 dB(A)) traffic controllers (p < 0.001). The corresponding figures for the 4 kHz notch were 31% versus 21% (p < 0.001). For the notch index, 61% of the exposed and 51% of the controls had a notched audiogram (p < 0.001). For female workers, the prevalence of audiometric notches was lower, and the differences between noise exposed and nonexposed was smaller than those in men. Increasing age led to an increased prevalence of notches.Conclusions:Audiometric notches commonly occur among both noise-exposed and those not exposed to noise in railway personnel. The usefulness of audiometric notches in the diagnosis of NIHL is therefore limited.

Analysis of 4 kHz Notch Audiogram as a Sign of Noise Induced Hearing Loss

Background and ObjectivesZZIn this study, we tried to study the criteria and characteristics of patients with noise-induced hearing loss by analyzing the pure tone audiogram such as “C5 dip” or “4 kHz notch”. Subjects and MethodZZOut of 553 patients who complained of tinnitus and hearing loss, medical examination by interview, physical examination, hearing test, brain MRI and survey of tinnitus were performed from January 2010 to December 2012, targeting 81 patients who underwent pure tone hearing test. We analyzed the clinical characteristics of 81 patients with the exception of systemic disease or a history of otologic disease, conductive hearing loss, and vestibular schwannomas. Patients consisted of 70 men and 11 women (34 persons on both sides, 31 persons on right side, and 16 persons on left side), with an average of 48.1±12.9 years. 4 kHz notch-type sensorineural hearing loss was compared with contralateral hearing.

Prevalence of occupational noise induced hearing loss in industrial workers

Introduction: Occupational noise induced hearing loss causes sensorineural hearing loss (SNHL) in industrial workers who are continuously exposed to high frequency noise due to degeneration in hair cells and associated nerve fibers. Materials and Methods: This study was conducted in 100 industrial male workers, including officials, machinery operators, and helpers. ENT and audiometry examination were done and noise level was measured. The age, noise level, duration of exposure, type of activity, and measurement of hearing loss were co-related. Results: The workers who worked in machinery area were affected more when compared to official and helpers. The age group 36-40 was affected more when compared to other age groups. Conclusions: Chronic exposure to noise is common hazard in industrial workers that affect bilateral cochlea and causes high frequency SNHL with 4 kHz notch. We observed 39% industrial workers who were exposed to noise level >87.3 dBA, for 8-12 h/day in textile and hard strip rolling mills in spite of noise free machine are recommended suffered from SNHL.

Measured hyperbolic-sine (sinh) CMOS results: A high-order 10 Hz–1 kHz notch filter for 50/60 Hz noise

This paper presents proof-of-concept measured results from CMOS hyperbolic-sine (sinh) filters fabricated in a commercially available 0.35µm CMOS technology. Results from two chips are reported: a practical sinh integrator and a high order (8th) notch filter dedicated to 50/60Hz noise rejection and synthesized by means of the proposed integrator. Linearity, frequency and noise measurements are reported. The notch frequency of the 8th order filter can be tuned over almost two decades. Its attenuation exceeds 70dB for the target frequency range of 20–60Hz and its dynamic range (for THD<4%) amounts to 89dB while consuming 8µW from a 2V power supply level. For an increased power consumption of 74µW its dynamic range (for THD<4%) exceeds 100dB.

Estéreos pessoais: hábitos auditivos e avaliação audiológica

OBJETIVO: Caracterizar os hábitos auditivos e relacioná-los aos achados audiológicos de adultos sem queixas auditivas, usuários de estéreos pessoais. MÉTODOS: Foram avaliados 85 indivíduos, com idades entre 18 e 34 anos, com audição normal, sem exposição a ruído ocupacional. Todos responderam a um questionário de hábitos auditivos, disponibilizado na Internet e foram convocados para a avaliação audiológica: Audiometria Altas Frequências, Emissões Otoacústicas Evocadas por Estímulo Transiente (EOAT) e Emissões Otoacústicas Evocadas por Produto de Distorção (EOAPD). RESULTADOS: Os participantes do estudo ficam expostos à música por mais de duas horas diárias, há mais de quatro anos, normalmente em meios de transporte. Observou-se um entalhe em 6 kHz no delineamento da configuração audiométrica a partir das médias dos limiares auditivos de via aérea, característico de PAIR. Quanto maior o tempo (em anos) de exposição ao som, maior a chance de ausência de EOAT e incidência de zumbido. A maioria se preocupa com a saúde auditiva e acredita que os maus hábitos podem causar danos à audição. CONCLUSÃO: Embora os indivíduos não tenham apresentado queixas auditivas, aspectos relacionados à exposição ao ruído foram evidenciados, tais como zumbido, estresse e relatos de dificuldade crescente de inteligibilidade de fala com o aumento do ruído ambiental.

Repeatability of Real-Ear-to-Coupler Differences Measured by an Acoustic Method for Determining Probe Tube Insertion Depth

This article reports the real-ear-to-coupler differences (RECD) of 24 children (46 ears) and the repeatability of measures for 30 ears. For measuring real-ear sound pressure level (SPL), the probe tube must be positioned close to the eardrum in order to be representative of the SPL at the eardrum. In this study, an acoustic method that used a 6 kHz standing wave minimum in the real ear to place the probe tube tip at 9 mm from the eardrum was used with custom earmoulds for measuring the real-ear portion of the RECD. The results showed a mean insertion depth from the inter-tragal notch of 24.4 mm. Across frequencies between 0.25 to 4 kHz, the test-retest difference was less than 1.0 dB, and the reliability coefficients ranged from 0.7 to 0.9. The finding on insertion depths from the inter-tragal notch confirms the appropriateness of recommendations for an insertion depth of 25 mm in measuring RECD of children of this age. Variability in measured insertion depths across individuals to achieve the same relative distance from the eardrums supports the use of the 6 kHz notch method for accurate real-ear SPL measurements. Intersubject variability is several times greater than variability associated with repeated measurements of a single subject. The repeatability of this method compares favourably with previous literature on measures using foam/immitance tips with constant probe tube insertion depth.

Hearing Thresholds in Electronics Sound Inspectors Exposed to Continuous and Impulsive Type Noises

O b j e c t i v e s: To investigate the relation between different types of exposure to noise and a classic sign of noise-induced hearing loss (NIHL); the audiometric notch. M e t h o d s: A cross-sectional epidemiological survey was carried out in electronics sound inspectors exposed to continuous and impulsive type noises. The noise levels in the working environments, and the audiometric hearing threshold levels were measured. Results: Electronics sound inspectors were exposed to impulsive noise ranging from 74.1 to 88.9 dBA. The hearing loss induced by impulsive noise was greater and was characterized by maximum loss at 6 kHz audiometric frequency, as opposed to the notch at 4 kHz that is typical of continuous noise. C o n c l u s i o n s: The results suggest that the probable effect of impulsive noise on hearing should be considered even when the exposure is within the 85 dB equivalent A-weighted level. To diagnose NIHL it is important to elicit a detailed and accurate history of exposure to noise. Although the notch at 4 kHz is a well established clinical sign and may be valuable in confirming the diagnosis, the 6 kHz notch is variable and of limited importance.

Audiometric notch as a sign of noise induced hearing loss

OBJECTIVESTo investigate the relation between different types of exposure to noise and a classic sign of noise induced hearing loss (NIHL), the audiometric notch.METHODSThe study sample had exposure to both...

Do radiofrequency radiation affect the auditory system of people with occupational exposure?

The present study intended to investigate whether radiofrequency (RF) affects auditory system of people who are occupationally exposed to RF in terms of noise-induced hearing loss (NIHL) or not. The study was carried out on 31 men from 26 to 53 years of age. All of them have been working in the Diyarbakir Radio Broadcasting Station. On the other hand, the control group was based on 30 unexposed voluntary and healthy men. The range of age for control group was the same as in the exposed group (experimental group). The results of the present study showed that the incidence of NIHL in the exposed group is more and more than that of the unexposed (control) group. The incidence of NIHL was approximately found 70 % for exposed group and 6% for unexposed group. The difference of the incidence of NIHL between exposed and unexposed groups were statistically found significant for right and left ears at "4 kHz notch" (p < 0.001). Hearing loss was not observed below 1 kHz. The percentage difference in the incidence of hearing loss (decibel) between control and experimental group was found insignificant for frequency below 1 kHz (p > 0.05). The experimental group was also divided to three subgroups of technicians, officers and men staying in the quarters of radio broadcasting station. Three subgroups were compared with one another statistically. The incidence of NIHL for the right ears of technicians was found higher than the officer (p < 0.05). The incidence of NIHL for the left ears of men staying in quarters was found higher than officers (p < 0.05). The other results of comparison were found insignificant (p > 0.05). In conclusion, the incidence of NIHL at "4 kHz Notch" in the experimental group was found more common than the control group.