Outcome parameters in speech audiometry: retrospective analysis of data and reporting quality in clinical studies.

OBJECTIVES: The use of standardized outcome parameters is essential for the comparability of clinical studies. Pure-tone audiometry and speech audiometry are widely used, but there is no systematic evaluation of the outcome parameters in clinical application. Nevertheless, there is presumably a great heterogeneity especially in the field of speech audiometry. This study presents a snapshot of the current situation of documentation and usage of outcome parameters in otologic research. STUDY DESIGN: Retrospective study of existing literature analyzing common speech audiometric test material and procedure MAIN OUTCOME MEASURES: Intervention Studies from 2012 to 2016 concerning hearing ability were eligible for evaluation. Studies were analyzed with regard to study design, pathology and intervention, speech audiometric parameters, pure-tone audiometry, implementation of reporting standards and journal related data. RESULTS: 279 studies were included. Over 50% of the analyzed studies lacked proper documentation. In the remaining studies, there was a broad variance concerning the documented speech audiometric parameters, most often with a fixed presentation level of 65 dB SPL. CONCLUSION: The lack of generally used standards for reporting hearing outcomes makes it difficult to compare results of different clinical studies. An adequate description of the methods would be a first and important step in improving reports on audiological outcomes.

FreeHear: A New Sound-Field Speech-in-Babble Hearing Assessment Tool.

Pure-tone threshold audiometry is currently the standard test of hearing. However, in everyday life, we are more concerned with listening to speech of moderate loudness and, specifically, listening to a particular talker against a background of other talkers. FreeHear delivers strings of three spoken digits (0-9, not 7) against a background babble via three loudspeakers placed in front and to either side of a listener. FreeHear is designed as a rapid, quantitative initial assessment of hearing using an adaptive algorithm. It is designed especially for children and for testing listeners who are using hearing devices. In this first report on FreeHear, we present developmental considerations and protocols and results of testing 100 children (4-13 years old) and 23 adults (18-30 years old). Two of the six 4 year olds and 91% of all older children completed full testing. Speech reception threshold (SRT) for digits and noise colocated at 0° or separated by 90° both improved linearly across 4 to 12 years old by 6 to 7 dB, with a further 2 dB improvement for the adults. These data suggested full maturation at approximately 15 years old SRTs at 90° digits/noise separation were better by approximately 6 dB than SRTs colocated at 0°. This spatial release from masking did not change significantly across age. Test-retest reliability was similar for children and adults (standard deviation of 2.05-2.91 dB SRT), with a mean practice improvement of 0.04-0.98 dB. FreeHear shows promise as a clinical test for both children and adults. Further trials in people with hearing impairment are ongoing.

Reference ranges and stability of auditory and vestibular measures in a comprehensive assessment battery for traumatic brain injury.

BACKGROUND: Audiology clinics have many tools available to evaluate auditory and vestibular complaints. However, many tools lack established normative ranges across the life span. We conducted this study to establish reference ranges across the life span for audiology/vestibular measures commonly used to evaluate patients with traumatic brain injury. MATERIALS AND METHODS: In this repeated measures study, 75 adults, ages 18-65 years, without a history of traumatic brain injury, underwent robust auditory/vestibular evaluations three times over six months, including rotational chair, videonystagmography, computerized dynamic posturography, vestibular evoked myogenic potentials, and retinal fundoscopy. RESULTS: Age effect was notable for transient evoked otoacoustic emissions, pure-tone audiometry, auditory brainstem response, auditory middle latency response, and auditory-steady state response at 4000 hertz (Hz). Older participants (50-65 years) were more likely to have delayed latency horizontal saccades, positional nystagmus, slowed lower-extremity motor control responses, and delayed latency ocular vestibular evoked myogenic potentials. Low to mid-frequency horizontal (0.003-4 Hz) and mid-frequency vertical (1-3 Hz) vestibulo-ocular reflex, otolith-mediated reflexes, dynamic visual acuity and balance measures were generally not influenced by age. Females had larger static subjective visual testing offset angles, longer cervical vestibular evoked myogenic potential P1 latency, faster velocity horizontal saccades, and quicker motor control latency for large backward translations than age-matched males. CONCLUSION: These reference ranges can be used to discern impairment within the auditory and vestibular pathway following traumatic brain injury in young to middle-aged adults. ID: TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01925963.

ISO estimates of noise-induced hearing impairment.

The revision of International Organization for Standardization (ISO) standard ISO 1999 [(1971). International Organization of Standardization, Geneva, Switzerland)] in 1990 was based on two noise and hearing study databases, one presented by Burns and Robinson [(1970). Hearing and Noise in Industry (Her Majesty's Stationary Office, London)] and the other by Passchier-Vermeer [(1968). Report No. 35 and Supplement to Report No. 35 (Institute for Public Health Engineering, the Netherlands)]. However, the mathematical expression of these data in ISO 1999 neither closely predicts the distribution of hearing threshold levels in these two databases nor those in the National Institute for Occupational Safety and Health database. As a result, lower estimates of the risk of noise-induced hearing impairment are found using ISO 1999. An explanation of the revision is needed to justify these lower risk values.

Self-Reported Hearing Loss and Pure Tone Audiometry for Screening in Primary Health Care Clinics.

OBJECTIVE: To evaluate the performance of self-reported hearing loss alone and in combination with pure tone audiometry screening in primary health care clinics in South Africa. DESIGN: Nonprobability purposive sampling was used at 2 primary health care clinics. A total of 1084 participants (mean age 41.2 years; SD 15.5 years; range 16-97 years, 74.0% female) were screened using self-report and audiometry screening. Those failing audiometric screening and a sample of those who passed audiometric screening were also assessed by diagnostic pure time audiometry, to confirm or negate the finding of a hearing loss. RESULTS: Four hundred and thirty-six participants (40.2%) self-reported a hearing loss with no significant association with gender or race. One hundred and thirty-six participant (12.5%) self-reported hearing loss and failed audiometry screening (35 dB HL at 1, 2, and 4 kHz). Combining self-report with a second stage audiometry screening revealed a high test accuracy (81.0%) for hearing loss, being most accurate (86.1%) to identify high-frequency hearing loss. CONCLUSION: While self-report of hearing loss is an easy and time-efficient screening method to use at primary health care clinics, its accuracy may be limited when used in isolation and it may not be sufficiently sensitive to detect hearing loss. Combining a simple audiometry screening as a second-stage screen can significantly improve overall performance and efficiency of the screening protocol.

Accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss: incorporating automatic conditional rescreening.

PURPOSE: To validate the accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss (HFHL) 'Occupational Earcheck (OEC)' incorporating an automatic conditional rescreening, in an occupationally noise-exposed population. Secondary objectives were to assess the effects of age on test accuracy measures, and to assess the test accuracy for different degrees of HFHL. METHODS: A study was conducted on cross-sectional data of occupational audiometric examinations, including the index test OEC and reference standard pure-tone air conduction audiometry, of 80 noise-exposed workers. Sensitivity, specificity, and likelihood ratios were calculated for the OEC, after automatic conditional rescreening, for a younger and an older age group, and for two degrees of HFHL (HFHL25: PTA3,4,6 ≥ 25 dB HL, and HFHL35: PTA3,4,6 ≥ 35 dB HL, both for at least one ear). RESULTS: Test specificity for HFHL25 after a single test was 63%, and improved to 93% after the automatic conditional rescreen. Test sensitivity for HFHL25 decreased from 65% to 59%. Test sensitivity and specificity including automatic conditional rescreening for HFHL35 was 94% and 90%, respectively. The positive likelihood ratio for HFHL25 was 8.4, and for HFHL35 9.4. The negative likelihood ratio for HFHL35 was below 0.1. CONCLUSIONS: The OEC is an appropriate screening test, especially for HFHL35. Normal-hearing workers who obtained a positive test result for the first test for one or two ears, benefit from having an automatic rescreen, resulting in an improvement of the test specificity, and hence prevent unnecessary referral.

Phyllis M. Tookey Kerridge and the science of audiometric standardization in Britain.

The provision of standardized hearing aids is now considered to be a crucial part of the UK National Health Service. Yet this is only explicable through reference to the career of a woman who has, until now, been entirely forgotten. Dr Phyllis Margaret Tookey Kerridge (1901-1940) was an authoritative figure in a variety of fields: medicine, physiology, otology and the construction of scientific apparatus. The astounding breadth of her professional qualifications allowed her to combine features of these fields and, later in her career, to position herself as a specialist to shape the discipline of audiometry. Rather than framing Kerridge in the classic 'heroic-woman' narrative, in this article we draw out the complexities of her career by focusing on her pursuit of standardization of hearing tests. Collaboration afforded her the necessary networks to explore the intricacies of accuracy in the measurement of hearing acuity, but her influence was enhanced by her ownership of Britain's first Western Electric (pure-tone) audiometer, which she placed in a specially designed and unique 'silence room'. The room became the centre of Kerridge's hearing aid clinic that, for the first time, allowed people to access free and impartial advice on hearing aid prescription. In becoming the guardian expert and advocate of the audiometer, Kerridge achieved an objectively quantified approach to hearing loss that eventually made the latter an object of technocratic intervention.

[Speech audiometric assessment of informational masking. German version]. / Sprachaudiometrische Erfassung von "informational masking".

BACKGROUND: In communication situations with multiple speakers, speech recognition is adversely affected by energetic masking (EM) and informational masking (IM). IM characterizes masking effects caused by irrelevant information from competing speakers. This work investigates an approach to assess IM based on the Oldenburg Sentence Test (OLSa). Furthermore, the influence of interaural time differences (ITD) and aging effects on IM are considered. MATERIALS AND METHODS: IM was measured by superimposing two sentences from the OLSa. The beginning of the target sentence was indicated by the keyword "Stefan". To segregate between target and masker sentences, ITDs from 50 to 400 µs were included. The participants were asked to selectively attend to the target sentence and repeat back the spoken words. Potential factors associated with speech recognition results were assessed by an auditory measure of temporal fine structure and a neuropsychological profile. 16 normal-hearing listeners between 18 and 77 years of age participated in the study. RESULTS: Despite the clinically normal-hearing participants, the analysis showed a significant relationship between speech recognition outcome and pure-tone thresholds. All participants benefited from small ITDs between the target and masker sentence with regard to the unmasking of IM. The magnitude of unmasking could not be explained by any of the factors assessed in this study. Error analysis and the comparison to the literature reveal that the OLSa could be a useful tool to assess IM. Also in line with the current literature is the relationship between speech recognition outcome and pure-tone thresholds, as well as the strong effect of ITDs on the release from IM. CONCLUSION: Speech audiometric assessment of IM is of high relevance with regard to everyday communication situations. Due to its structure, the OLSa seems to be a useful tool for determining IM.

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.

Estudio normativo: umbrales auditivos de alta frecuencia (9-20 kHz) en normoyentes entre 8 años y 23 años y 11 meses, pertenecientes a la ciudad de Chillán / Normative study: high frequency hearing tresholds (9-20kHz) in normal-hearing patients in between the ages of 8 and 23 years and 11 months old, from Chillan city

Introducción: Diversos estudios evidencian que la audiometría de alta frecuencia cumple un importante rol en la detección temprana de pérdida auditiva; sin embargo, en Chile aún no se dispone de una normativa para su aplicación clínica. Objetivo: Normalizar los umbrales audiométricos de alta frecuencia (9-20 kHz) en normoyentes entre 8 y 23 años y 11 meses pertenecientes a la ciudad de Chillán. Material y método: No experimental, tipo descriptivo y corte transversal. Se evaluaron a 259 sujetos normoyentes, estudiantes de enseñanza básica, media y universitaria. A la muestra se le aplicó una audiometría de alta frecuencia, empleando un audiómetro (Gradson Stadler) GSI61 con fonoauriculares (Sennheiser) HDA 200. Resultados: Los umbrales auditivos incrementaron su valor según la edad y frecuencia. No se encontraron diferencias significativas según sexo. Se observaron diferencias significativas interaural en 9, 10 y 14 kHz. Los valores de los umbrales se presentaron en percentiles, considerando como normalidad aquellos ubicados entre el P10 y P75. Conclusión: Esta norma podría ser utilizada como referencia de normalidad para pesquisar tempranamente a sujetos en riesgo de pérdida auditiva y tomar las acciones sanitarias más pertinentes a cada caso en particular, empleando equipamiento similar.

Introduction: There are several studies showing that high frequency audiometry serves the important purpose in hearing loss early detection; nonetheless, Chile does not have a standard regulation for clinical implementation of the previously mentioned exam. Aim: To standardize high frequency thresholds (9-20) in patients with normal hearing in between the ages of 8 and 23 years and 11 months old from Chillan city. Material and method: Non-experimental, descriptive and held in a transversal lapse of time. 259 normal-hearing subjects were evaluated, belonging to elementary, middle, high school and higher -university- levels of education. All subjects underwent a high-frequency audiometry for which was used a (Gradson Stadler) GSI61 audiometer, with (Sennheiser) HDA 200 headphones. Results: It was observed that high-frequency thresholds tended to increase their figures according to age and frequency requirements. No meaningful differences -regarding male or female subjects- were found, although there were note worthy differences in 9, 10 and 14 kHz frequencies. The numbers of the thresholds were presented as percentiles, considering 'normal' those located in between P10 and P75. Conclusion: This regulation can be used as a point of reference for normality in order to early detect subjects having a hearing loss risk, and to also take health-related action suitable for each particular case, by using similar equipment to the one described in this study.

A software tool for pure­tone audiometry. Classification of audiograms for inclusion of patients in clinical trials. English version.

OBJECTIVE: Selecting subjects for clinical trials on hearing loss therapies relies on the patient meeting the audiological inclusion criteria. In studies on the treatment of idiopathic sudden sensorineural hearing loss, the patient's acute audiogram is usually compared with a previous audiogram, the audiogram of the non-affected ear, or a normal audiogram according to an ISO standard. Generally, many more patients are screened than actually fulfill the particular inclusion criteria. The inclusion criteria often require a calculation of pure-tone averages, selection of the most affected frequencies, and calculation of hearing loss differences. MATERIALS AND METHODS: A software tool was developed to simplify and accelerate this inclusion procedure for investigators to estimate the possible recruitment rate during the planning phase of a clinical trial and during the actual study. This tool is Microsoft Excel-based and easy to modify to meet the particular inclusion criteria of a specific clinical trial. The tool was retrospectively evaluated on 100 patients with acute hearing loss comparing the times for classifying automatically and manually. The study sample comprised 100 patients with idiopathic sudden sensorineural hearing loss. RESULTS AND CONCLUSION: The age- and sex-related normative audiogram was calculated automatically by the tool and the hearing impairment was graded. The estimated recruitment rate of our sample was quickly calculated. Information about meeting the inclusion criteria was provided instantaneously. A significant reduction of 30 % in the time required for classifying (30 s per patient) was observed.

Is this STS work-related? ISO 1999 predictions as an adjunct to clinical judgment.

BACKGROUND: Physicians and audiologists are often asked to decide whether standard threshold shifts (STSs) are work-related; epidemiological data can inform these decisions. METHODS: Predictions of ISO (2013) for both age-related and noise-induced threshold shifts, for the 2, 3, and 4 kHz average used in calculating OSHA STSs, are presented, in tables, graphs, and an Excel spreadsheet calculator. Specifically, the ISO 1999 model estimates age-related thresholds based on age and sex; it estimates noise-induced threshold shifts based on noise level and duration. It specifies that to estimate the final hearing thresholds for a person of given percentile, age, sex, and noise exposure, the expected age-related threshold is to be added to the expected noise-induced threshold shift. Examples show how these data can predict the relative contributions of aging and occupational noise to an STS. RESULTS: Early-career STSs, especially with high levels of noise exposure, are more likely to be primarily noise-induced. After the first decade of exposure, most STSs will be primarily age-related. CONCLUSION: Given a worker's age, sex, and occupational noise exposure history, ISO 1999 estimates of the expected contributions of aging and noise can supplement clinical judgment.

Distribution characteristics of normal pure-tone thresholds.

OBJECTIVE: This study examined the statistical properties of normal air-conduction thresholds obtained with automated and manual audiometry to test the hypothesis that thresholds are normally distributed and to examine the distributions for evidence of bias in manual testing. DESIGN: Four databases were mined for normal thresholds. One contained audiograms obtained with an automated method. The other three were obtained with manual audiometry. Frequency distributions were examined for four test frequencies (250, 500, 1000, and 2000 Hz). STUDY SAMPLE: The analysis is based on 317 569 threshold determinations of 80 547 subjects from four clinical databases. RESULTS: Frequency distributions of thresholds obtained with automated audiometry are normal in form. Corrected for age, the mean thresholds are within 1.5 dB of reference equivalent threshold sound pressure levels. Frequency distributions of thresholds obtained by manual audiometry are shifted toward higher thresholds. Two of the three datasets obtained by manual audiometry are positively skewed. CONCLUSIONS: The positive shift and skew of the manual audiometry data may result from tester bias. The striking scarcity of thresholds below 0 dB HL suggests that audiologists place less importance on identifying low thresholds than they do for higher-level thresholds. We refer to this as the Good enough bias and suggest that it may be responsible for differences in distributions of thresholds obtained by automated and manual audiometry.

Hearing threshold levels for an otologically screened population in Spain.

OBJECTIVE: The aim of the present study was to provide thresholds data as a function of age for an otologically normal population in Spain, compared to the current ISO 7029 (2000) standard. DESIGN: A prospective study in an otologically screened population. STUDY SAMPLE: Data was collected from 1175 otologically-normal persons aged between 5 and 90 years. Inclusion criteria involved those listed in ISO 389-1 (1998) and the 8253-1 (2010). Suitability for inclusion was evaluated through interview, based on a questionnaire, and physical examination. RESULTS: The hearing thresholds decreased slightly from 125 to 2000 Hz. From 2000 Hz onwards the thresholds increased; this increase being more pronounced with increasing frequency and age. No statistically significant sex differences were found. The hearing threshold levels in the present study were higher (poorer) than the ones provided by ISO 7029 (2000). CONCLUSIONS: Results from this study suggest that the thresholds listed in ISO 7029 (2000) may be too restrictive, and could be useful in formulating the ISO 7029 update.

Reference hearing thresholds in an extended frequency range as a function of age.

The ISO 7029 (2000) standard defines normative hearing thresholds H (dB hearing level) as a function of age Y (years), given by H = α(Y - 18)(2), up to 8 kHz. The purpose of this study was to determine reference thresholds above 8 kHz. Hearing thresholds were examined using pure-tone audiometry over the extended frequency range 0.125-16 kHz, and the acquired values were used to specify the optimal approximation of the dependence of hearing thresholds on age. A sample of 411 otologically normal men and women 16-70 years of age was measured in both ears using a high-frequency audiometer and Sennheiser HDA 200 headphones. The coefficients of quadratic, linear, polynomial and power-law approximations were calculated using the least-squares fitting procedure. The approximation combining the square function H = α(Y - 18)(2) with a power-law function H = ß(Y - 18)(1.5), both gender-independent, was found to be the most appropriate. Coefficient α was determined at frequencies of 9 kHz (α = 0.021), 10 kHz (α = 0.024), 11.2 kHz (α = 0.029), and coefficient ß at frequencies of 12.5 kHz (ß = 0.24), 14 kHz (ß = 0.32), 16 kHz (ß = 0.36). The results could be used to determine age-dependent normal hearing thresholds in an extended frequency range and to normalize hearing thresholds when comparing participants differing in age.

[Development and use of an APHAB database]. / Entwicklung und Anwendung einer APHAB-Datenbank.

A specific quality assurance questionnaire concerned with the provision of hearing aids was introduced that assesses elements of patient satisfaction within Germany's statutory healthcare system. A questionnaire-based assessment is now relevant for all physicians involved in the care of statutorily insured patients in Germany. The APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire is the most widely used. The APHAB assesses several different situations: the normal hearing situation, hearing in noise, comprehension of speech in situations of echo or reverberation and hearing in loud situations. The APHAB questionnaire-based patient evaluation of the benefit of hearing aids represents the third pillar of audiological diagnostics, alongside classical pure-tone and speech audiometry. The objective of the APHAB database is to allow evaluation of individual patient data on the basis of a larger volume of data.

Ambient noise impact on accuracy of automated hearing assessment.

OBJECTIVE: The aim of this study was to determine the effect of ambient noise on the accuracy of thresholds obtained using the KUDUwave portable clinical audiometer as compared to those obtained using a GSI-61 clinical audiometer in a sound booth. DESIGN: Pure-tone air conduction thresholds were obtained in three conditions: (1) with a clinical audiometer in a quiet sound booth, (2) with the KUDUwave in a quiet sound booth, and (3) with the KUDUwave with 40 dBA of background noise. STUDY SAMPLE: A total of 31 individuals ranging in age from 15 to 80 years participated in the study, 21 with normal hearing and ten with hearing loss. RESULTS: Eighty-nine percent of thresholds obtained with the KUDUwave in quiet, and 92% of thresholds obtained with the KUDUwave in background noise were within 5 dB of those obtained with the clinical audiometer. Accuracy was poorer at 250 Hz and 8000 Hz. CONCLUSION: Ambient noise typical of that found in a non-sound-treated room, did not affect the accuracy of air conduction hearing thresholds obtained with the KUDUwave. The KUDUwave may be a viable method of testing when a clinical audiometer and sound booth are not available.

A treatise on the thresholds of interoctave frequencies: 1500, 3000, and 6000 Hz.

BACKGROUND: For the past 50+ years, audiologists have been taught to measure the pure-tone thresholds at the interoctave frequencies when the thresholds at adjacent octave frequencies differ by 20 dB or more. Although this so-called 20 dB rule is logical when enhanced audiometric resolution is required, the origin of the rule is elusive, and a thorough literature search failed to find supporting scientific data. PURPOSE: This study purposed to examine whether a 20 dB difference between thresholds at adjacent octave frequencies is the critical value for whether the threshold of the interoctave frequency should be measured. Along this same line of questioning is whether interoctave thresholds can be predicted from the thresholds of the adjacent or bounding octave frequencies instead of measured, thereby saving valuable time. RESEARCH DESIGN: Retrospective, descriptive, correlational, and cross-sectional. STUDY SAMPLE: Audiograms from over a million veterans provided the data, which were archived at the Department of Veterans Affairs, Denver Acquisition and Logistics Center. DATA COLLECTION AND ANALYSIS: Data from the left and right ears were independently evaluated. For each ear three interoctave frequencies (1500, 3000, and 6000 Hz) were studied. For inclusion, thresholds at the interoctave frequency and the two bounding octave frequencies had to be measurable, which produced unequal numbers of participants in each of the six conditions (2 ears by 3 interoctave frequencies). Age tags were maintained with each of the six conditions. RESULTS: Three areas of analyses were considered. First, relations among the octave-frequency thresholds were examined. About 62% of the 1000-2000 Hz threshold differences were ≥20 dB, whereas about 74% of the 4000-8000 Hz threshold differences were <20 dB. About half of the threshold differences between 2000 and 4000 Hz were <20 dB and half were >20 dB. There was an inverse relation between frequency and the percent of negative slopes between octave-frequency thresholds, ranging from 89% at 1500 Hz to 54% at 6000 Hz. The majority of octave-frequency pairs demonstrated poorer thresholds for the higher frequency of the pair. Second, interoctave frequency thresholds were evaluated using the median metric. As the interoctave frequency increased from 1500 to 6000 Hz, the percent of thresholds at the interoctave frequencies that were not equal to the median threshold increased from ∼9.5% (1500 Hz) to 15.6% (3000 Hz) to 28.2% (6000 Hz). Bivariate plots of the interoctave thresholds and the mean octave-frequency thresholds produced 0.85-0.91 R² values and 0.79-0.92 dB/dB slopes. Third, the predictability of the interoctave thresholds from the mean thresholds of the bounding octave frequencies was evaluated. As expected, as the disparity between octave-frequency thresholds increased, the predictability of the interoctave threshold decreased; for example, using a ±5 dB criterion at 1500 Hz, 53% of the thresholds were ±5 dB when the octave thresholds differed by ≥20 dB, whereas 77% were ±5 dB when the octave thresholds differed by <20 dB. CONCLUSIONS: The current findings support the 20 dB rule for testing interoctave frequency thresholds and suggest the rule could be increased to 25 dB or more with little adverse effect.

Extended high-frequency (9-20 kHz) audiometry reference thresholds in 645 healthy subjects.

OBJECTIVE: The aim of the present study was to study patterns in the extended spectrum of the human hearing (0.125 to 20 kHz) in order to obtain reference thresholds. Then, we compare our values with existing results at extended high-frequencies (8 to 20 kHz) in an attempt to establish new standards for potential international adoption. DESIGN: A prospective study in a group of otologically healthy subjects. STUDY SAMPLE: A total of 645 subjects aged between 5 and 90 years were recruited. Pure-tone thresholds were determined for conventional and extended high-frequencies. RESULTS: There was an increase in the hearing thresholds as a function of frequency and age. For the 20 to 69 years old group, thresholds were lower in females than in males, especially at 12.5 and 16 kHz. Our threshold values are comparable to those presented in previous studies that used different instrumentation and populations. CONCLUSIONS: When comparing different studies the hearing thresholds were found to be similar. Therefore, it would be possible to establish international standard thresholds.