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.

Abstract This research on military aviation noise was conducted because the personnel working with military aircraft were concerned about noise induced hearing damage. In addition, comprehensive data on hearing impairments and occupational exposure of military pilots in the Finnish Air Force was not available. Moreover, data on the effects of overflight noise of military jets was necessary for the evaluation of noise induced hearing deteriorations of members of the public who might be exposured accidentally for the low-level jets' overflights. The averaged noise exposure levels of pilots varied during a flight from 97 dB(A) to 106 dB(A) in the cockpit and from 83 dB(A) to 100 dB(A) at the entrance of the ear canal. Radio noise was 4–10 dB higher than background noise inside the helmet. The attenuation provided by air crew helmets varied from10 to 21 dB(A) in the laboratory, and was at the same level during real flights. The attenuation measured in the laboratory and in working conditions was about 30 dB(A) for earmuffs. An active noise cancellation (ANC) device decreased averaged noise exposure (LAeq8min) 4–8 dB over the noise attenuation of the same helmets when the ANC system was off. The noise of overflights by military jets were measured and the noise levels were lower than those known to cause the permanent threshold shifts. However, noise induced hearing damages might be possible in certain conditions. In order to assess the hearing loss risk of pilots, hearing thresholds were measured before and after one flight using both conventional and extended high frequency (EHF) audiometry. Minor temporary threshold shifts (TTS) were revealed. The risk of noise-induced damage at the studied exposure levels is, in all probability, rather small. A novel NoiseScan data management system proved to be an interesting tool in assessment of the risk of developing hearing impairment on the basis of known risk factors. Due to the small number of risk factors, the hearing of pilots was shown to be at considerably less risk than that of industrial workers in Finland.

En hörselnedsättning är en kommunikationsstörning som starkt påverkar en bebis utveckling på många områden, inte bara ljudperception och talad kommunikation. I Sverige screenas idag alla bebisar redan på BB, för att så tidigt som möjligt upptäcka medfödda skador. Dessa metoder har dock informationsbegränsningar angående hörselnedsättningens grad och frekvensberoende. När bebisar är ett halvår gamla kan den observerande audiometriska metoden Visual Reinforcement Audiometry (VRA) användas för att utreda hörselnedsättningen. Metoden baseras på att en audionom gör en subjektiv bedömning om bebisen reagerar och vänder huvudet till följd av presenterade ljudstimuli med känt frekvensinnehåll och känd ljudtrycksnivå. År 2009 genomfördes tester med en prototyp för att utreda om VRA-metoden lämpar sig att kombinera med eye-tracking. Detta för att kunna tidigarelägga utredningar eftersom bebisen inte behöver kontrollera sina nackrörelser, utan reaktionsbekräftan kan baseras på förändringar i bebisens blickfokus. Insamlad data var dock svårtolkad, men gav indikationer om att fortsatt arbete kunde leda till en mer objektiv version av VRA-metoden, lämpad för låga åldrar.I detta examensarbete har idén om ett eye-trackerbaserat hörseltest vidareutvecklats vilket resulterat i en ny prototypgeneration, grundad på ny metod för att fastställa hörnivåer. Metoden har främst släktskap med Békésy-metoden, med dynamiska ljudtrycksnivåer, men tar även den individuella reaktionslatensen i beaktning för att bedöma hörnivån vid tidpunkten patienten stimulerades att reagera, inte då reaktionen senare kunde registreras. Ett utredande arbete med studiebesök hos praktiserande audionomer, observationer av tester med föregående prototyp samt en fokusgruppdiskussion har resulterat i ett nytt användargränssnitt och en ny SQL-databasdriven resultathantering för att stödja forskning. Produktutvecklingen har även resulterat i en omarbetad konditioneringsfas, där bebisen fixerar blicken på ett objekt, som efter ett presenterat ljud kan bytas mot en belöning i form av en webbkameraström med t.ex. föräldern. Projektdeltagarna, som arbetat agilt enligt Deming-cykeln (även kallad PDCA), har löpande planerat, utvecklat, testat och tagit beslut med hjälp av funktionsprototyper som pilottestats på totalt 21 bebisar, 1 barn och 6 vuxna. Projektet avslutades med två verifierande tester. I det ena testades fem femmånaders bebisar för att bekräfta att hörnivåer kan bedömas vid en tidig ålder med den nya audiometriska metoden. För 80 % av bebisarna kunde, under en testsession, en till åtta hörtrösklar utredas. Det andra testet utredde precisionen i metoden jämfört med rentonsaudiometri utförd av Karolinska Universitetssjukhuset. Resultatet visar på en medelvägd differens om c:a 3 dB respektive 6-8,5 dB för de båda testdeltagarna. Fortsatt bekräftas att kombinationen av VRA-metoden och reaktionsdetektion med en eye-tracker kan realiseras även vid låga patientåldrar. Den nyutvecklade metoden för att bestämma hörnivåer visar på hög precision, men behöver fortsatt verifiering i likvärdiga testmiljöer samt evidensforskning. / Hearing impairment is a communication disorder which greatly affects an infant’s development in many areas, not just in sound perception and oral communication. Today all babies in Sweden are screened already in the maternity hospital, in order to detect birth defects as early as possible. However, the information given by these methods are limited in terms of how severe the hearing loss is and its frequency dependency. At six months of age the infants hearing reduction can be investigated by using the observation based audiometric method, Visual Reinforcement Audiometry (VRA). The method is based on an audiologist’s subjective observation of the infant’s reactions; to turn its head towards a reward due to sound stimuli of known frequency and sound pressure level. In 2009, a prototype was developed in order to investigate whether the VRA method is suitable to combine with eye tracking. The investigations could thus be performed earlier since the baby does not need to control their head movements, but the reaction detection can be based on changes in the infants gaze. The collected data were difficult to interpret, but indicated that further work could lead to a more objective version of the VRA method, suitable for infants of low age.In this thesis, the idea of an eye-tracker based hearing test has been further developed and has resulted in a new prototype generation, based on an entirely new method of determining hearing thresholds. The method are mostly related to the Békésy method, with dynamic sound pressure levels, but also takes the individual reaction latency into consideration in order to assess the hearing threshold. The assessment is based on the moment in time when the patient was stimulated to react, not when the latter reaction could be recorded. An investigative work based on a study of practicing audiologists, observation of tests with the previous prototype and a focus group discussion has led to a new user interface and a new SQL database-driven results handling in order to support research. The product development has also resulted in a revised conditioning phase. When the infant moves its gaze from a fixation object, due to sound stimuli, the object can be exchanged with a reward in the form of a webcam stream with e.g. the infant’s parent. Project participants, who have been working agile according to the Deming Cycle (also called PDCA), have regularly planned, developed, tested and taken decisions using prototypes which were pilot tested on a total of 21 babies, 1 child and 6 adults. The project was finalized with two verifying tests. In one of the tests five five-month old babies were tested in order to confirm that hearing thresholds can be assessed at low ages by the new audiometric method. One to four frequencies could be investigated during one test session with 80% of the babies. The second test investigated the accuracy of the method compared to pure tone audiometry, conducted at the Karolinska University Hospital. The results show an average weighted difference of approximately 3 dB respectively 6-8.5 dB for the participants. The combination of the VRA method with reaction detection via an eye-tracker remains realizable, even for infant patients. The newly developed method for determining hearing thresholds shows high precision, but needs further verification in identical test environments and further evidence-research.

published_or_final_version / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / abstract / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / Speech and Hearing Sciences / Doctoral / Doctor of Philosophy

Dichotic tests evaluate binaural integration through simultaneous presentation of different stimuli to each ear of a listener who has normal hearing sensitivity in both ears. Dichotic listening deficits may lead to problems with language, communication, reading, or academic performance. If accurately identified, dichotic deficits may be treatable with listening training or managed with accommodation. However, it is not clear which of several commercially-available dichotic test recordings are best for audiologists to use when assessing binaural integration in children. Literature review revealed limited evidence of reliability, accuracy, usefulness, or value for dichotic tests applied to children. Of 11 dichotic tests identified, five reported some evidence of test-retest reliability. Correlation between results on repeated administration was moderate to good (r=0.59 to 0.92). Evidence of accuracy was identified for 5 tests but was not generalizable due to significant limitations in study design. No evidence was found to either support or dispute claims of usefulness or value. Since reliability is a necessary prerequisite for good test performance, we sought to directly compare test-retest reliability for three dichotic measures: SCAN-3 Competing Words (CW), Musiek's Double Dichotic Digits (DD-M), and Bergen Dichotic Listening Test with Consonant-Vowel Syllables (CV-B). Sixty English-speaking children, 7-14 years old with normal hearing, had a single study-visit during which each test was administered twice. Changes on retest were compared to binomial model predictions, summarized by within-subject standard deviation (Sw), and compared among tests. Correlates of variance were explored. All 3 tests had reliability within bounds predicted by binomial model. Forty-item scores were more reliable (Sw=5%) than those based on 20-30 items (Sw=6-8%). No associations between participant characteristics and reliability were found. CW and DD-M were evaluated for evidence of agreement and decision consistency. Although participants were rank ordered similarly by right ear (ρ = 0.58), left ear (ρ = 0.51) and total (ρ = 0.73) scores, the tests did not agree on ranking by inter-aural asymmetry (ρ =0.18). CW and DD-M did not agree on direction of ear advantage (κ = 0.01, p = 0.93) and had poor agreement on which children displayed dichotic deficits (κ = 0.22, p < 0.01). DD identified significantly more participants with deficits (n=18) than CW (n=3) (p < 0.001). Although dichotic procedures show moderate reliability, their precision is limited. Assessment of their accuracy is limited by the absence of a widely-accepted gold standard reference test, but two commonly used tests failed to agree on which children had deficits. The data do not yet support routine clinical use of dichotic tests of binaural integration with children. Additional research is needed to determine if there are any conditions under which dichotic procedures demonstrate usefulness or value.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Zuzana Pokorná Supervisor: Doc. RNDr. Petr Klemera, CSc. Title of diploma thesis: Resveratrol - effect on the biological age Objective: Resveratrol is a natural polyphenol contained in number of plants. It is a potent antioxidant, which is known to have a number of beneficial health effects and be part of many biological processes. The compound is produced by plants to increase their survival and resistance to disease. We found the effect of Resveratrol on parameters of biological age-on the threshold of perception of the intensity of the volume (hearing) and reaction rate. Methods : A group of people used the resveratrol in a dose of 170 mg per day for 40 days. We measured by the PC program the selected parameter of hearing and reaction rate. Results : It has been shown that statistically significant improvement of hearing has occurred. The exact mechanism of the effect is not known. Probably operates through a group of enzymes, sirtuins. Reaction rate was not affected by substance. Conclusions : We have reviewed the potential effect of Resveratrol on human biological age. The improvement of hearing has been shown at the 0,01 significance level. The biggest improvement was...

Doctor Educationis / Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).