Supra-aural Earphones Research Articles

Examination of Insert Ear Interaural Attenuation (IA)Values in Audiological Evaluations

The purpose of this study was to evaluate Interaural Attenuation (IA) in frequency base in the insert earphones that are used in audiological assessments. Thirty healthy subjects between 18-65 years of age (14 female and 16 male) participated in our study. Otoscopic examination was performed on all participants. Audiological evaluations were performed using the Interacoustics AC40 clinical audiometer and ER-3A insert earphones. IA value was calculated by subtracting good ear bone conduction hearing thresholds of the worst airway hearing threshold. In our measuring for 0.125-8.0 kHz frequency were performed in our audiometry device separately for each frequency. IA amount in the results we found in 1000 Hz and below frequencies about 75-110 dB range avarage is 89±5dB, in above 1000 Hz frequencies in 50-95 dB range and avarage it is changed to 69±5dB. According to the obtained findings the quantity of melting in the transition between the ears are increasing with the insert earphones. The insert earphone should be beside supraaural earphone that is routinely used in clinics. Difficult masking applications due to the increase in the value of IA can be easily done with insert earphones.

Computer-controlled audiometer's application as an earplug fit-testing tool

Clinical audiometers are usually coupled with a calibrated pair of TDH-39 headphones, supra-aural earphones that rest on a person’s ears. Hearing protector testing with these types of earphones is problematic due to a couple of reasons; the earplug may protrude from the ear canal and come in contact with the earphone thereby alerting the individual that the earplug is likely not inserted adequately or the earphone may impend on the position and affect the seal of the earplug and thereby void any measurement data. Deeper supraural ear-cup cushions were 3D printed for the TDH-39 headphones in order to allow for an insert earplug to be fit-tested without interference. The 3D printed set of ear-cups was calibrated to the computer-controlled audiometer and 20 subjects were tested in the unoccluded and occluded conditions. The differences between the two measurements at each of the seven frequencies tested (i.e., 500, 1000, 2000, 3000, 4000, 6000, and 8000Hz) were averaged across subjects, personal attenuation ratings computed. Results are compared with a commercially available hearing protective device field attenuation estimation system (i.e., fit-check or fit-test system).

The Hearing Aid ‘Effect’ as a Function of Race and Gender

The Hearing Aid ‘Effect’ as a Function of Race and Gender

Affordable headphones for accessible screening audiometry: An evaluation of the Sennheiser HD202 II supra-aural headphone

Objective: Evaluation of the Sennheiser HD 202 II supra-aural headphones as an alternative headphone to enable more affordable hearing screening. Design: Study 1 measured the equivalent threshold sound pressure levels (ETSPL) of the Sennheiser HD 202 II. Study 2 evaluated the attenuation of the headphones. Study 3 determined headphone characteristics by analyzing the total harmonic distortion (THD), frequency response and force of the headband. Study sample: Twenty-five participants were included in study 1 and 15 in study 2 with ages ranging between 18 and 25. No participants were involved in study 3. Results: The Sennheiser HD 202 II ETSPLs (250–16000 Hz) showed no significant effects on ETSPL for ear laterality, gender or age. Attenuation was not significantly different (p > 0.01) to TDH 39 except at 8000 Hz (p < 0.01). Maximum permissible ambient noise levels (MPANL) were specified accordingly. The force of the headband was 3.1N. THD measurements showed that between 500 and 8000 Hz intensities of 90 dB HL and higher can be reached without THD >3%. Conclusion: Sennheiser HD 202 II supra-aural headphones can be used as an affordable headphone for screening audiometry provided reported MPANLs, maximum intensities and ETSPL values are employed.

Efficacy of earphones for 12- to 24-month-old children during visual reinforcement audiometry

Objective: Efficacy of insert and supra-aural earphones during visual reinforcement audiometry (VRA) was investigated for 12- to 24-month-old children. Design: VRA testing began in the soundfield and transitioned to either insert or supra-aural earphones. Audiologists recorded threshold estimates, participant behaviors, and an overall subjective rating of earphone acceptance. Study sample: One hundred and eighty-six 12- to 24-month-old children referred to the Department of Audiology at St. Louis Children’s Hospital for a variety of reasons. Results: Subjective ratings indicated high acceptance of insert earphones (84%) and supra-aural earphones (80%) despite negative behaviors. There was no significant difference in the number of threshold estimates based on earphone type for 12- to 17-month-old participants. Participants in the 18- to 24-month-old age group provided significantly more threshold estimates with insert earphones (mean = 5.3 threshold estimates, SD = 3.5) than with supra-aural earphones (mean = 2.9 threshold estimates, SD = 2.9). All seven participants who rejected earphone placement were successfully reconditioned for soundfield testing. Conclusions: Data support the use of insert earphones during VRA, especially with 18-to 24-month-old children, to obtain ear-specific information.

Audiometric Thresholds: Stimulus Considerations in Sound Field and Under Earphones.

This study evaluates a new stimulus, FREquency Specific Hearing assessment (FRESH) noise, to obtain hearing thresholds and reviews the potential pitfalls of using narrow band noise. Twelve adults with simulated gradually sloping hearing loss and 12 adults with steeply sloping hearing loss participated. Hearing thresholds were measured in sound field and under a supraaural earphone for FRESH noise, warbled tones, and narrowband noise. Pure-tone thresholds were also measured under the supraaural earphone. FRESH noise thresholds were similar to pure-tone and warbled-tone thresholds regardless of audiometric configuration. For the group with gradually sloping hearing loss, thresholds obtained with narrowband noise were approximately 4 dB better than those obtained with the other test stimuli. For the group with steeply sloping hearing loss, narrowband noise significantly underestimated hearing thresholds-the steeper the hearing loss, the greater the underestimation. When hearing loss is suspected, FRESH noise is appropriate for accurately determining audiometric thresholds in sound field and under earphones. A wider band, attention-getting stimulus such as narrowband noise can result in thresholds that are inaccurate. Clinical decision making regarding choice of test stimulus is discussed.

The effect of the transducers on paediatric thresholds estimated with auditory steady-state responses.

The objective of this study was to investigate the usefulness of auditory steady-state responses (ASSRs) for estimating hearing thresholds in young children, compared with behavioural thresholds. The second objective was to investigate ASSR thresholds obtained with insert earphones versus supra-aural headphones to determine which transducer produces ASSR thresholds most similar to behavioural thresholds measured with supra-aural headphones. This retrospective study included 29 participants (58 ears): 12 children (24 ears) in the insert group and 17 children (34 ears) in the supra-aural group. No general anaesthesia was used. For both groups, there was a strong correlation between behavioural and ASSR thresholds, with a stronger correlation for the insert group. When behavioural thresholds are difficult to obtain, ASSR may be a useful objective measure that can be combined with other audiometric procedures to estimate hearing thresholds and to determine appropriate auditory rehabilitation approaches.

Variabilidade teste-reteste na audiometria tonal: comparação entre dois transdutores

Objetivo Caracterizar a variabilidade teste-reteste com fones supra-aurais e fones de inserção e comparar os limiares auditivos tonais entre os transdutores.Métodos Foram selecionados 74 indivíduos de ambos os gêneros, com limiares auditivos normais e curvas timpanométricas do tipo A. Todos os indivíduos foram submetidos à anamnese, meatoscopia, audiometria tonal por via aérea, ora com o fone supra-aural, ora com o fone de inserção, e logoaudiometria. Após esta primeira avaliação, foi realizada a medida de imitância acústica. Por fim, os procedimentos de audiometria tonal foram repetidos.Resultados O fone supra-aural produziu maior variabilidade teste-reteste, quando comparado com o fone de inserção. Já na comparação dos transdutores, verificou-se, tanto na primeira, quanto na segunda testagem, que as respostas mostraram-se ora semelhantes, ora favorecendo um ou outro transdutor.Conclusão Há maior variabilidade teste-reteste com o fone supra-aural do que com o fone de inserção. No entanto, foram verificados melhores limiares na condição reteste, para ambos os transdutores.

An Experimental Study on Maximum Sound Output Capabilities and Preferred Listening Levels Using Different Earphone Types

Objective: The study aims to compare the maximum sound output capabilities of different earphone types/music style combinations. The study also intends to assess the preferred listening levels (PLL) of test subjects using different earphone types with background noise accession. The study also seeks to determine the presence or absence of a threshold shift on headphone/music style combination PLL’s that exceed the recommended noise limit.&#x0D; Methods&#x0D; Study Design: Experimental Study&#x0D; Setting: Tertiary Government Hospital&#x0D; Subjects: Thirty (30) hearing healthy volunteers were sampled from hospital staff aged 18-40 years, with no known history of ear pathology and/or use of any known ototoxic drugs, with normal otoscopy and audiograms of less than 20dB from 125Hz to 8000Hz, and no exposure to loud noise from any source within the previous 3 days.&#x0D; The sound pressure levels (SPL) delivered by three (3) types of earphones (earbud type, in-ear type, supra-aural type) were measured at maximum volume setting of a personal media player (iPod, Apple Inc.), while playing different music genres. The test subjects were asked to listen at their preferred listening levels (PLL) using the different types of earphones at increasing background noise accession.&#x0D; Results: The earbud type averaged the greatest SPL among the earphone types, and pop music averaged the greatest SPL among the music styles. Comparison of the maximum output capabilities revealed that there was a significant difference among different brands of earphones of the same type. However, no significant difference were found among songs of similar music style and across different music styles in all earphones except the in-ear type. PLL average was at 90.4dB in a silent environment with increasing intensity as background noise accentuated. Supra-aural earphones registered the least increase in PLL in a loud environment, due to its higher background noise-attenuating capabilities.&#x0D; Conclusion: Having a significant difference among earphone types with regard their maximum output capabilities, it is recommended to check the specifications of the earphone type one intends to use. In using personal media players (PMP), the volume should be set at the lowest comfortable level. While choice of music style remains the discretion of the listener, the choice of music style should be considered for long periods of listening. Because the PLL of test subjects were alarmingly high, the authors recommend intervention in their listening habits. Background noise attenuating capabilities of earphones play a factor in reducing excessive sound energy from reaching the ear, reducing the PLL, and decreasing the risk for noise-induced hearing loss.&#x0D; Keywords: earphones, music styles, personal media players, preferred listening levels, recreational noise, noise-induced hearing loss

The Efficacy of Routine Screening for High-Frequency Hearing Loss in Adults and Children.

This study was conducted to investigate the efficacy of routine screening for high-frequency hearing loss (HFHL) including 3000, 6000, and 8000 Hz frequencies with conventional test frequencies (1000, 2000, and 4000 Hz) in adults and children in a university outreach program. Screening outcomes were examined in 2 cohorts of adults (Cohort 1, N = 315, M = 66.2 years; Cohort 2, N = 67, M = 68.3 years) and children (Cohort 1, N = 177, M = 6.5 years; Cohort 2, N = 57, M = 6.9 years) with a high-frequency screen protocol (1000-8000 Hz at 25 dB HL for adults and 20 dB HL for children) using supra-aural headphones. A rescreen was conducted in Cohort 2 with a modified protocol using insert earphones and monitored ambient noise levels. Average total test time significantly increased (p < .0001) and nearly doubled with inclusion of 3000-, 6000-, and 8000-Hz frequencies, adding approximately 1 min. Rescreen referral rates decreased by approximately 2%-16% at 1000-8000 Hz (approximately 13%-16% at 6000 and 8000 Hz) using the modified protocol in adults and children, supporting false-positive responses using supra-aural headphones. Screening for HFHL should include insert earphones in order to prevent potential errors, particularly at 6000 and 8000 Hz.

Potencial evocado auditivo de tronco encefálico por condução óssea: uma revisão integrativa

O objetivo deste estudo foi de realizar uma revisão de forma integrativa sobre os procedimentos utilizados nos critérios de aquisição do exame de Potenciais Evocados Auditivos de Tronco Encefálico por condução óssea com fins ao auxílio no diagnóstico de problemas auditivos. Foi realizada uma busca nas seguintes bases de dados: Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs), Medical Literature Analysis and Retrieval System Online (Medline) e Scientific Eletronic Library Online (SciELO). Utilizaram-se as seguintes palavras-chave: Potencial Evocado Auditivo, Eletrofisiologia e Condução Óssea, encontrados por meio de Descritores em Ciências da Saúde (DeCS). Os resultados apresentados são referentes aos 35 estudos selecionados. A maioria dos estudos optou pelo uso do estímulo clique, com transdutores por condução aérea os fones supra-aurais, como o TDH-39, para o estímulo por condução óssea, o vibrador Radioear B-71, com pressão de 425+/-25g. Observou-se que a mastoide foi à região onde mais se posicionou mais o vibrador ósseo. A maioria dos estudos refere usar polaridade alternada, com taxa de apresentação diversificada, sendo 57,7/s a mais utilizada e filtro de 30-3000 Hz, com uma janela de 15 ms de duração. Para taxa do estímulo a maioria dos estudos utilizou de 2048, e um total de estímulos de 2 registros. O Potencial Evocado Auditivo de Tronco Encefálico é um exame que vem sendo pesquisado há muitos anos e muito se tem descrito na literatura sobre seus aspectos de aquisição e analise, além de destacar a importância da sua utilização na população neonatal.

Audio–vocal responses of vocal fundamental frequency and formant during sustained vowel vocalizations in different noises

Sustained vocalizations of vowels [a], [i], and syllable [mə] were collected in twenty normal-hearing individuals. On vocalizations, five conditions of different audio–vocal feedback were introduced separately to the speakers including no masking, wearing supra-aural headphones only, speech-noise masking, high-pass noise masking, and broad-band-noise masking. Power spectral analysis of vocal fundamental frequency (F0) was used to evaluate the modulations of F0 and linear-predictive-coding was used to acquire first two formants. The results showed that while the formant frequencies were not significantly shifted, low-frequency modulations (<3 Hz) of F0 significantly increased with reduced audio–vocal feedback across speech sounds and were significantly correlated with auditory awareness of speakers' own voices. For sustained speech production, the motor speech controls on F0 may depend on a feedback mechanism while articulation should rely more on a feedforward mechanism. Power spectral analysis of F0 might be applied to evaluate audio–vocal control for various hearing and neurological disorders in the future.

In-situ audiometry: How close is it to conventional audiometry?

Technology in the hearing aid industry is ever changing. One of the many features that may improve accuracy of hearing aid fittings and patients’ satisfaction is the inception of in-situ audiometry, which allows the clinician to measure hearing thresholds with a hearing aid in the patient's ear. Objective: The present study aimed to investigate the validity of in-situ audiometry measured with a behind-the-ear hearing aid coupled to a customized earmould relative to conventional thresholds measured using supra-aural head phones. Study design: A total of 24 ears from 15 participants with varying degrees of sensorineural hearing loss ranging from moderate to severe, were selected for the study. Pure tone hearing thresholds and real-ear-to-dial-differences were measured for both conventional and in-situ thresholds across 250 Hz to 6 kHz. Results: Slight but significant mean differences (p ˂ 0.05, paired t-test) of 3.2 and 3.4dB between conventional and in-situ thresholds at 2000 and 6000 Hz were found before adding REDD corrections with in-situ thresholds yielding better (lower) thresholds. Except at 250 Hz in dB HL, individual threshold variability between conventional and in-situ threshold measurements was within or equal to ± 10dB for > 95% of ears before and after adding REDD corrections. Large inter-participant variation in measured ear canal SPL was noticed at 250, 500, 4000 and 6000 Hz when measured in-situ compared to headphones, which was attributed to differences in earmould vent sizes provided for different degrees of hearing loss at the low frequencies and probe placement in the high frequencies. Conclusion: Overall in-situ audiometry proved to be valid especially in individuals with symmetrical sensorineural hearing loss. Although there are statistically significant differences, they are within clinically accepted standards. Furthermore, thresholds measured in ear canal SPL will be more comparable as any changes in hearing threshold levels in either of the measurements will be reflected by an inverse change in measured ear canal SPL during REDD measurements.

Air conduction, bone conduction, and soft tissue conduction audiograms in normal hearing and simulated hearing losses.

In order to differentiate between a conductive hearing loss (CHL) and a sensorineural hearing loss (SNHL) in the hearing-impaired individual, we compared thresholds to air conduction (AC) and bone conduction (BC) auditory stimulation. The presence of a gap between these thresholds (an air-bone gap) is taken as a sign of a CHL, whereas similar threshold elevations reflect an SNHL. This is based on the assumption that BC stimulation directly excites the inner ear, bypassing the middle ear. However, several of the classic mechanisms of BC stimulation such as ossicular chain inertia and the occlusion effect involve middle ear structures. An additional mode of auditory stimulation, called soft tissue conduction (STC; also called nonosseous BC) has been demonstrated, in which the clinical bone vibrator elicits hearing when it is applied to soft tissue sites on the head, neck, and thorax. The purpose of this study was to assess the relative contributions of threshold determinations to stimulation by STC, in addition to AC and osseous BC, to the differential diagnosis between a CHL and an SNHL. Baseline auditory thresholds were determined in normal participants to AC (supra-aural earphones), BC (B71 bone vibrator at the mastoid, with 5 N application force), and STC (B71 bone vibrator) to the submental area and to the submandibular triangle with 5 N application force) stimulation in response to 0.5, 1.0, 2.0, and 4.0 kHz tones. A CHL was then simulated in the participants by means of an ear plug. Separately, an SNHL was simulated in these participants with 30 dB effective masking. STUDY SAMPLE consisted of 10 normal-hearing participants (4 males; 6 females, aged 20-30 yr). AC, BC, and STC thresholds were determined in the initial normal state and in the presence of each of the simulations. The earplug-induced CHL simulation led to a mean AC threshold elevation of 21-37 dB (depending on frequency), but not of BC and STC thresholds. The masking-induced SNHL led to a mean elevation of AC, BC, and STC thresholds (23-36 dB, depending on frequency). In each type of simulation, the BC threshold shift was similar to that of the STC threshold shift. These results, which show a similar threshold shift for STC and for BC as a result of these simulations, together with additional clinical and laboratory findings, provide evidence that BC thresholds likely represent the threshold of the nonosseous BC (STC) component of multicomponent BC at the BC stimulation site, and thereby succeed in clinical practice to contribute to the differential diagnosis. This also provides evidence that STC (nonosseous BC) stimulation at low intensities probably does not involve components of the middle ear, represents true cochlear function, and therefore can also contribute to a differential diagnosis (e.g., in situations where the clinical bone vibrator cannot be applied to the mastoid or forehead with a 5 N force, such as in severe skull fracture).

Stimulus and transducer effects on threshold

Objective: This study examined differences in thresholds obtained under Sennheiser HDA200 circumaural earphones using pure tone, equivalent rectangular noise bands, and 1/3 octave noise bands relative to thresholds obtained using Telephonics TDH-39P supra-aural earphones. Design: Thresholds were obtained via each transducer and stimulus condition six times within a 10-day period. Study sample: Forty-nine adults were selected from a prior study to represent low, moderate, and high threshold reliability. Results: The results suggested that (1) only small adjustments were needed to reach equivalent TDH-39P thresholds, (2) pure-tone thresholds obtained with HDA200 circumaural earphones had reliability equal to or better than those obtained using TDH-39P earphones, (3) the reliability of noise-band thresholds improved with broader stimulus bandwidth and was either equal to or better than pure-tone thresholds, and (4) frequency-specificity declined with stimulus bandwidths greater than one equivalent rectangular band, which could complicate early detection of hearing changes that occur within a narrow frequency range. Conclusions: These data suggest that circumaural earphones such as the HDA200 headphones provide better reliability for audiometric testing as compared to the TDH-39P earphones. These data support the use of noise bands, preferably ERB noises, as stimuli for audiometric monitoring.

Audiometric profile of civilian pilots according to noise exposure.

OBJECTIVE To evaluate the audiometric profile of civilian pilots according to the noise exposure level.METHODS This observational cross-sectional study evaluated 3,130 male civilian pilots aged between 17 and 59 years. These pilots were subjected to audiometric examinations for obtaining or revalidating the functional capacity certificate in 2011. The degree of hearing loss was classified as normal, suspected noise-induced hearing loss, and no suspected hearing loss with other associated complications. Pure-tone air-conduction audiometry was performed using supra-aural headphones and acoustic stimulus of the pure-tone type, containing tone thresholds of frequencies between 250 Hz and 6,000 Hz. The independent variables were professional categories, length of service, hours of flight, and right or left ear. The dependent variable was pilots with suspected noise-induced hearing loss. The noise exposure level was considered low/medium or high, and the latter involved periods > 5,000 flight hours and > 10 years of flight service.RESULTS A total of 29.3% pilots had suspected noise-induced hearing loss, which was bilateral in 12.8% and predominant in the left ear (23.7%). The number of pilots with suspected hearing loss increased as the noise exposure level increased.CONCLUSIONS Hearing loss in civilian pilots may be associated with noise exposure during the period of service and hours of flight.

Provisional stimulus level corrections for low frequency bone-conduction ABR in babies under three months corrected age

Objective: To estimate bone-conduction stimulus level corrections by testing the auditory brainstem response (ABR) of normally-hearing newborns. The stimuli used were low frequency tone pips calibrated to reference levels derived from ISO 389 values. Design: Tone pips were presented via supra-aural earphones and a B71 Radioear bone vibrator at 0.5 or 1 kHz. ABR thresholds from both transducers were compared at each frequency. Study sample: twenty-seven newborn hearing screening referrals (33 ears) who passed an ABR discharge criterion at 4 kHz. Results: Median air- and bone-conduction ABR threshold differences were 30 dB at 0.5 kHz and 20 dB at 1 kHz. Conclusion: The 0.5 kHz data from this study and previous studies were compared. Previous studies suggested lower figures for the bone-conduction stimulus level correction. Likely sources of this discrepancy are discussed. The average 0.5 kHz bone-conduction correction value for infants < 3 months old is about 28 dB. The correction for 1 kHz is 20 dB. We recommend that calibration reference levels used in this study be adopted and that appropriate corrections be applied to bone conduction ABR thresholds in infants < 3 months old before calculation of any air-bone gap and subsequent clinical interpretation.

Hearing screening for school children: utility of noise-cancelling headphones.

BackgroundExcessive ambient noise in school settings is a major concern for school hearing screening as it typically masks pure tone test stimuli (particularly 500 Hz and below). This results in false positive findings and subsequent unnecessary follow-up. With advances in technology, noise-cancelling headphones have been developed that reduce low frequency noise by superimposing an anti-phase signal onto the primary noise. This research study examined the utility of noise-cancelling headphone technology in a school hearing screening environment.MethodsThe present study compared the audiometric screening results obtained from two air-conduction transducers—Sennheiser PXC450 noise-cancelling circumaural headphones (NC headphones) and conventional TDH-39 supra-aural earphones. Pure-tone hearing screening results (500 Hz to 4000 Hz, at 30 dB HL and 25 dB HL) were obtained from 232 school children, aged 6 to 8 years, in four Hong Kong primary schools.ResultsScreening outcomes revealed significant differences in referral rates between TDH-39 earphones and NC headphones for both 30 dB HL and 25 dB HL criteria, regardless of the inclusion or exclusion of 500 Hz results. The kappa observed agreement (OA) showed that at both screening intensities, the transducers’ referral agreement value for the 500 Hz inclusion group was smaller than for the 500 Hz exclusion group. Individual frequency analysis showed that the two transducers screened similarly at 1000 Hz and 2000 Hz at 25 dB HL, as well as at both 30 dB HL and 25 dB HL screening levels for 4000 Hz. Statistically significant differences were found for 500 Hz at 30 dB HL and at 25 dB HL, and for 1000 Hz and 2000 Hz at 30 dB HL. OA for individual frequencies showed weaker intra-frequency agreement between the two transducers at 500 Hz at both intensity criterion levels than at higher frequencies.ConclusionsNC headphones screening results differed from those obtained from TDH-39 earphones, with lower referral rates at 500 Hz, particularly at the 25 dB HL criterion level. Therefore, NC headphones may be able to operate at lower screening intensities and subsequently increase pure-tone screening test sensitivity, without compromising specificity. NC headphones show some promise as possible replacements for conventional earphones in school hearing screening programs.

Output capabilities of personal music players and assessment of preferred listening levels of test subjects: Outlining recommendations for preventing music‐induced hearing loss

Our goal was to assess the impact of personal music players, earphones, and music styles on output, the subject's preferred listening levels, and outline recommendations for the prevention of music-induced hearing loss. Experimental study. Personal music players' output capabilities and volunteers' preferred output levels were assessed in different settings. Based on current noise-induced hearing loss exposure limits, recommendations were outlined. On three different devices and earphone types and 10 music styles, free field equivalent sound pressure output levels were assessed by applying a microphone probe inside the auditory canal. Forty-five hearing-healthy volunteers were asked to select preferred listening levels in different background noise scenarios. Sound pressure output reached 126 dB. No difference was found between device types, whereas earbud and supra-aural earphones showed significantly lower outputs than in-ear earphones (P < .001). Three distinct music style groups were identified with as much as 14.4 dB difference between them. In silence, 17.8% of volunteers spontaneously selected a listening level above 85 dB. With 90 dB background noise, 40% selected a level above 94 dB. Earphone attenuation capability was found to correlate significantly with preferred level reductions (r = 0.585, P < .001). In-ear and especially supra-aural earphones reduced preferred listening levels the most. Safe-use recommendations were outlined, whereas selecting the lowest volume setting comfortable remained the main suggestion. High background noise attenuating earphones may help in reducing comfortable listening levels and should be preferred. A risk table was elaborated, presenting time limits before reaching a risky exposure.

Measurements of earplug attenuation under supra-aural and circumaural headphones

Objective: Supra-aural audiometric headphones are generally not recommended for use in measuring the attenuation of earplugs, because contact between the headphone and pinna and/or earplug could alter the attenuation obtained, and because of concerns of non-comparability between modes of excitation from supra-aural headphones and the sound-field procedure required by the standardized method. In this study, we compared measurements of earplug attenuation obtained under Telephonics TDH-50P supra-aural headphones with measurements obtained under circumaural headphones designed expressly for such testing. Design: The attenuation of three types of earplugs (foam, premolded quadruple-flange, and custom-molded) was measured in a repeated-measures design. Study sample: The study sample comprised 42 normal-hearing adults (21 females, 21 males). Results: With the foam earplugs, nearly all of the attenuation measurements under the supra-aural headphones fell within 10 dB of the measurements under the circumaural headphones. With the flange and custom earplugs, approximately 10% of individuals obtained spuriously high attenuation under the supra-aural headphones. Conclusions: We conclude that standard supra-aural audiometric headphones are suitable for measuring the attenuation provided by foam earplugs. However, supra-aural headphones should not be used to measure the attenuation of flange or custom-molded earplugs. The potential exists for substantial over-estimation of attenuation, especially of custom plugs.