Effect of Sugar-Free Jelly on Glycemic Metabolism and Its Potential Health Benefits in Non-Diabetic Adults.

Excessive sugar consumption provides energy but has little nutritional value, contributing to the prevalence of obesity. Hence, "sugar-free" products using artificial or natural sweeteners, including sugar alcohols, have become popular. Accordingly, safety concerns and curiosity have arisen. Therefore, this study used a double-blind, crossover design to compare the effects of commercial sugar-free and sugar jellies (control) on the glycemic response in 16 adults without diabetes. Blood samples were collected to measure blood glucose, insulin, glucagon, ghrelin, C-peptide, glycated hemoglobin, and glycated albumin levels, and an oral glucose tolerance test was performed. Questionnaires on satiety and intestinal health were also administered. Sugar-free jellies resulted in significantly lower glucose and insulin levels and a reduced area under the curve while showing higher glucagon levels than the controls. Moreover, the sugar-free jelly initially resulted in the greater secretion of ghrelin; however, after 2 h, the control jelly resulted in higher ghrelin. No significant differences were observed in gut quotient, C-peptide, glycated hemoglobin, and glycated albumin levels. In conclusion, substituting sugar jelly with sugar-free jelly may induce lower blood glucose and insulin levels and higher glucagon levels, indicating a better ability to control glucose metabolism. Appetite was not stimulated by sugar-free jelly consumption.

Association of Central Auditory Processing Dysfunction With Preclinical Alzheimer's Disease.

OBJECTIVE: To investigate whether central auditory processing dysfunction measured by the dichotic digit test-1 digit (DDT1) is present in preclinical Alzheimer's disease (AD) individuals who are cognitively normal (CN) older adults with the cerebral beta-amyloid (Aß) deposition and to explore the potential of the DDT1 as a screening test for preclinical AD. STUDY DESIGN: Cross-sectional design. SETTING: A prospective observational cohort study. METHODS: CN older adults with a global clinical dementia rating score of 0 were included. The hearing test battery including pure-tone audiometry, speech audiometry, distortion product otoacoustic emission, and DDT1 was administered to participants. RESULTS: Fifty CN older adults were included. Among them, 38 individuals were included in the Aß deposition negative (AN) group and 12 were included in the Aß deposition positive (AP) group. The DDT1 scores of both the better and worse ears were significantly lower in the AP group than in the AN group (p = .008 and p = .015, respectively). No significant differences were observed between the groups in tests of the peripheral auditory pathways. In multivariable logistic regression analysis adjusted for apolipoprotein E4 positivity, the DDT1 better ear score predicted the AP group (p = .036, odds ratio = 0.892, 95% confidence interval: 0.780-0.985) with relatively high diagnostic accuracy. CONCLUSION: Our findings suggest that Aß deposition may affect the central auditory pathway even before cognitive decline appears. DDT1, which can easily be applied to the old-age population, may have the potential as a screening tool for preclinical AD.

Status of the Newborn Hearing Screening in the 4-Months Age National Infant Health Checkup in Korea: A Nationwide Population-Based Study.

BACKGROUND: The aims of this study are to review data on 4-months age National Health Screening Program for Infants and Children (NHSPIC) using a National Health Insurance Service (NHIS) database, and to analyze the newborn hearing screening (NHS) results and related characteristics of the 4-months NHSPIC for 7 years in South Korea. METHODS: We analyzed a NHIS database of infants who had participated in the 4-month age NHSPIC from 2010 to 2016. According to the results of hearing questionnaires and physical examination, we analyzed the outcomes of NHS and related infantile and socioeconomic factors. RESULTS: Among 3,128,924 of total eligible infants in Korea between the year 2010 and 2016, 69.2% (2,164,621 infants) conducted 4-months age NHSPIC, and 94.4% (2,042,577 infants) of which performed hearing questionnaires regarding NHS. Among the total hearing examinees, premature infants accounted for 3.6%, infants who were hospitalized in the neonatal intensive care unit (NICU) for more than 5 days accounted for 5.6%, and infants with head and neck abnormalities were 0.6%. The NHS performing rate was 79.1% for total hearing examinees in 2010, but gradually increased to 88.9% in 2016. The NHS performing rate in 2016 was 93.4% for premature infants, 91.7% for NICU hospitalized babies. The mean referral rate was 0.6% for total hearing examinees, 1.4% for premature infants, and 2.3% for NICU hospitalized babies. When we analyzed the NHS performing rate and the referral rate according to the household income level, the NHS performing rate of infants in Medical Aid programs was the lowest as 65.6%, and the NHS performing rates in other five levels of NHIS was higher ranging between 85.1% to 86.0%. The referral rate of infants in the Medical Aid program (3.8%) was significantly higher than those of infants in other classes (1.10-1.25%). CONCLUSION: The estimated overall NHS performing rate in Korea gradually increased and was 88.9% in 2016. The overall referral rate was low as 0.6%, and it was significantly different depending on the infant's health condition and household income levels. We assume that our finding would help to establish policies managing hearing impaired children, and to develop the customized hearing care service programs considering the household economic levels.

Enhanced Dichotic Listening and Temporal Sequencing Ability in Early-Blind Individuals.

Several studies have reported the better auditory performance of early-blind subjects over sighted subjects. However, few studies have compared the auditory functions of both hemispheres or evaluated interhemispheric transfer and binaural integration in blind individuals. Therefore, we evaluated whether there are differences in dichotic listening, auditory temporal sequencing ability, or speech perception in noise (all of which have been used to diagnose central auditory processing disorder) between early-blind subjects and sighted subjects. The study included 23 early-blind subjects and 22 age-matched sighted subjects. In the dichotic listening test (three-digit pair), the early-blind subjects achieved higher scores than the sighted subjects in the left ear (p = 0.003, Bonferroni's corrected α = 0.05/6 = 0.008), but not in the right ear, indicating a right ear advantage in sighted subjects (p < 0.001) but not in early-blind subjects. In the frequency patterning test (five tones), the early-blind subjects performed better (both ears in the humming response, but the left ear only in the labeling response) than the sighted subjects (p < 0.008, Bonferroni's corrected α = 0.05/6 = 0.008). Monosyllable perception in noise tended to be better in early-blind subjects than in sighted subjects at a signal-to-noise ratio of -8 (p = 0.054), the results at signal-to-noise ratios of -4, 0, +4, and +8 did not differ. Acoustic change complex responses to/ba/in babble noise, recorded with electroencephalography, showed a greater N1 peak amplitude at only FC5 electrode under a signal-to-noise ratio of -8 and -4 dB in the early-blind subjects than in the sighted subjects (p = 0.004 and p = 0.003, respectively, Bonferroni's corrected α = 0.05/5 = 0.01). The results of this study revealed early-blind subjects exhibited some advantages in dichotic listening, and temporal sequencing ability compared to those shown in sighted subjects. These advantages may be attributable to the enhanced activity of the central auditory nervous system, especially the right hemisphere function, and the transfer of auditory information between the two hemispheres.

Aggregation-Enhanced Photoluminescence and Photoacoustics of Atomically Precise Gold Nanoclusters in Lipid Nanodiscs (NANO2).

The authors designed a structurally stable nano-in-nano (NANO2) system highly capable of bioimaging via an aggregation-enhanced NIR excited emission and photoacoustic response achieved based on atomically precise gold nanoclusters protected by linear thiolated ligands [Au25(SC n H2n+1)18, n = 4-16] encapsulated in discoidal phospholipid bicelles through a one-pot synthesis. The detailed morphological characterization of NANO2 is conducted using cryogenic transmission electron microscopy, small/wide angle X-ray scattering with the support of molecular dynamics simulations, providing information on the location of Au nanoclusters in NANO2. The photoluminescence observed for NANO2 is 20-60 times more intense than that of the free Au nanoclusters, with both excitation and emission wavelengths in the near-infrared range, and the photoacoustic signal is more than tripled. The authors attribute this newly discovered aggregation-enhanced photoluminescence and photoacoustic signals to the restriction of intramolecular motion of the clusters' ligands. With the advantages of biocompatibility and high cellular uptake, NANO2 is potentially applicable for both in vitro and in vivo imaging, as the authors demonstrate with NIR excited emission from in vitro A549 human lung and the KB human cervical cancer cells.

Status of early hearing detection and intervention in South Korea: a nationwide population-based study of national infant health checkup.

The aim of this study was to evaluate the status of early hearing detection and intervention after newborn hearing screening (NHS) in South Korea. A retrospective review of Korean national health insurance service data of all infants receiving the 4-month old national infant health checkup between 2010 and 2016 from a nationwide population-based database was conducted. Based on the results of the NHS-administered hearing questionnaires as part of the national infant health checkup, individuals were classified into "pass" (1,730,615 infants) or "refer" (10,941 infants) groups. Next, an analysis was conducted of age and the frequencies of tracking audiologic tests and surgeries of the middle ear (ME) and cochlear implants (CI). Diagnostic auditory brainstem response and audiometry, and surgeries of ME and CI were significantly performed more and earlier in the refer group compared with the pass group. For infants in the pass group who were presumed to have delayed or acquired hearing loss, the time of the first audiology tests and CI surgery was significantly delayed compared to those in the refer group; the average ages for first CI were 37 and 52 months in the refer group and pass group, respectively. Therefore, for early detection of delayed-onset hearing loss, regular hearing screening programs should be considered throughout the preschool ages.

Rate of chronic otitis media operations and cholesteatoma surgeries in South Korea: a nationwide population-based study (2006-2018).

The aim of this study was to estimate the total number and rate of chronic otitis media (COM) operations and cholesteatoma surgeries in South Korea, using a nationwide survey which analysed a 13-year trend (2006-2018). This study also analysed the trend of COM operations and cholesteatoma surgeries according to year, sex, and age using a nationwide population-based database, and the 13-year trend was analysed according to age groups. This study used nationwide data from the National Health Information Database (NHID), which is a government-affiliated agency under the Korean Ministry of Health and Welfare that supervises all medical activities in Korea. Retrospective medical data of patients of all ages were extracted from the NHID from January 2006 to December 2018 (NHIS-2018). This study was conducted by the Research Committee of the Korean Society of Otorhinolaryngology-Head and Neck Surgery, and the Korean Audiological Society reviewed and confirmed the study. There was a 1.5 fold increase in COM operation rates in 2018, compared to 2007 figures. The annual total number of COM operations was 5,935 in 2007, 8,999 in 2012 (peak), and 8,870 in 2018 (17 in 100,000). Meanwhile, the total annual number of cholesteatoma surgeries decreased from 3,502 in 2006 to 3,199 in 2018 (6 in 100,000). The rate of COM operations was higher (1.27 fold) in the female population than in the males in 2018. However, cholesteatoma surgery rates were higher (1.2 fold) in the male population than in the females in 2018. According to the 2018 data, COM operations were most commonly performed in patients in their 50s. COM operation rates increased rapidly in patients aged 51-80. In other age groups however, rates were constant or showed a decrease in figures, especially in the 40s age group (1st rank in 2006 to 3rd rank in 2018). According to the 2018 data, cholesteatoma surgery was most commonly performed in patients in their 50s. Cholesteatoma surgery rates increased dramatically from 2006 to 2018 in patients aged 0-10 years due to congenital cholesteatoma. Cholesteatoma surgery rates also increased in patients aged 61-80 years due to ageing population. Cholesteatoma surgery rates decreased in patients aged 41-50 years, ranking 1st in 2006 and 4th in 2018. In conclusion, the annual rate of COM operations was 0.017%, and no longer increases, but stabilizes/decreased after a peak point in the advanced country. The mean rate of cholesteatoma surgery was 0.006%, and decreased annually. There was female dominance in COM operations, but male dominance in cholesteatoma surgery. Major age groups of patients who underwent COM/cholesteatoma surgery were the 50s and 60s, and congenital cholesteatoma (0-10 years) accounted for about 20% of all cholesteatoma surgery.

Development of the Jordanian Arabic early speech perception test.

INTRODUCTION: The Early Speech Perception (ESP) test has been previously used to assess speech perception skills in young hearing-impaired children. As the Arabic language is known to be diglossic, the purpose of this study was to develop a Colloquial Jordanian Arabic version (JAESP) of the ESP test and to check its usefulness. METHODS: The JAESP test encompasses four categories: detection of speech sounds, speech pattern perception, disyllabic word identification, and monosyllabic word identification. Picture boards representing the test materials were created and two equivalent lists for each test category were made. The word identification task was used to test a total of 43 children with reported normal-hearing abilities (15 children aged 3 years, 15 aged 4 years, and 13 aged 5 years). RESULTS: The scores for all age groups were 98-100% for all test materials. Statistical analysis showed that there was no significant difference between age groups and between lists (p ˃ 0.05). CONCLUSION: The findings of this study indicate that the JAESP test materials are appropriate for Jordanian children who are at least 3 years old. Additional studies are needed to verify the validity of the test materials for Jordanian hearing-impaired children.

Impact of hearing loss on the performance of auditory processing measured by questionnaires in Korean adolescents.

Increasing use of personal listening devices has been accompanied by increase in the prevalence of hearing loss (HL) among youth in Korea, as in other countries. Auditory processing disorder (APD) is one of the main factors affecting academic achievement at school. This study aimed to investigate the prevalence of HL in students attending general middle- and high schools and compare the findings with the APD survey results. From June 1 to December 31, 2016, Korean adolescents (n = 2,791) in the first years of middle- and high school underwent audiometric testing and otologic examination and completed questionnaires on APD. The survey was sponsored by the Korean Society of Otolaryngology-Head and Neck Surgery and the Korean Otology Society. The prevalence of speech-frequency hearing loss (SFHL) and high-frequency hearing loss (HFHL) in the poorer ear was 11.6% and 10.3%, respectively, among Korean adolescents. We analysed data from the Scale of Auditory Behaviors, Fisher's Auditory Problems Checklist, and KNISE-Auditory Behavioral Checklist and compared these with the results of hearing tests. We observed positive correlations among the APD questionnaire results and mean hearing levels. This study suggested that hearing loss, especially bilateral high-frequency hearing loss, may affect central auditory processing.

Apparatus to Measure Subnanometer Fluctuation of Giant Unilamellar Vesicle Membranes.

The design, calibration, and performance of an apparatus are described to study the nanometer-scale thermal or driven fluctuations of free-standing vesicle membranes using a design resembling the position detection system of optical tweezers except for the laser power lower by orders of magnitude to avoid trapping. Over four decades of frequency, 1-10,000 Hz, it reports membrane fluctuation amplitudes 0.01-100 nm by measuring scattering of a laser beam as it passes membranes (∼1 µm cross-section) suspended in the aqueous medium. The low-power laser beam, <100 µW, is sharply focused on the edge of a giant unilamellar vesicle, and fluctuations of position are measured using a position-sensitive photodetector. The central result of this approach is the capability to reach small fluctuations otherwise inaccessible using other techniques. The typical obtained data are fit to the standard Helfrich mechanical model. The applications and limitations of the device are discussed, as well as other potential uses to which the apparatus may be applied by rational extension of the approach presented.

WHO implementation workshop on guidelines on procedures and data requirements for changes to approved biotherapeutic products, Seoul, Republic of Korea, 25-26 June 2019.

The first global workshop on implementation of the WHO guidelines on procedures and data requirements for changes to approved biotherapeutic products adopted by the WHO Expert Committee in 2018 was held in June 2019. The workshop participants recognized that the principles based on sound science and the potential for risk, as described in the WHO Guidelines on post-approval changes, which constitute the global standard for product life-cycle management are providing clarity and helping national regulatory authorities in establishing guidance while improving time-lines for an efficient regulation of products. Consequently, the regulatory situation for post-approval changes and guideline implementation is changing but there is a disparity between different countries. While the guidelines are gradually being implemented in some countries and also being considered in other countries, the need for regional workshops and further training on post-approval changes was a common theme reiterated by many participants. Given the complexities relating to post-approval changes in different regions/countries, there was a clear understanding among all participants that an efficient approach for product life-cycle management at a national level is needed to ensure faster availability of high standard, safe and efficacious medicines to patients as per the World Health Assembly Resolution 67.21.

Biologically-active unilamellar vesicles from red blood cells.

We demonstrate a method to prepare giant unilamellar vesicles (GUVs) with biologically-active protein activity, by mixing erythrocyte (red blood cell) membrane extract with phospholipids and growing their mixture in a porous hydrogel matrix. This presents a pathway to retain protein biological activity without prior isolation and purification of the protein, though only the activity of the membrane protein GLUT1 is investigated to date. Using the cascade enzymatic reaction glucose oxidase and horseradish peroxidase to assay glucose concentration specifically within the GUV interior, we show that glucose is internalized by GLUT1 whereas adding cytochalasin B, a GLUT1 inhibitor, blocks glucose transport. The method presented here operates at biological ionic strength and is both simple and potentially generalizable.

Prevalence of severe-profound hearing loss in South Korea: a nationwide population-based study to analyse a 10-year trend (2006-2015).

To estimate prevalence of severe-profound hearing loss (HL) in South Korea, and analyse a 10-year trend of HL according to age, sex, and region by using a nationwide population-based database. Retrospective review from Korean National Health Insurance Service from 2006 to 2015. The degree of severe-profound HL was classified into six grades, based mostly on HL worse than 60 dB HL for both ears. Absolute number of HL was the highest in 2011 (0.25 million; males, 0.14 million; females, 0.11 million); it decreased gradually until 2015. Total HL prevalence was the highest in 2010 (0.5%; 251,954), and decreased annually to 2015 (0.46%; 237,272). The trend of HL prevalence showed a gradual decrease from 2010 to 2015. Prevalence of severe-profound HL was always higher in the male population (1.19 times higher than female in 2015). Prevalence of HL was higher in rural areas than in urban areas (1.4 times higher in 2015). Number of severe-profound HL in South Korea decreased gradually in all age groups annually, even though some older age groups had the highest peak in 2010-2011. Prevalence of severe-profound HL decreases gradually in all age groups annually in South Korea, although the absolute number of HL cases increases rapidly among those aged over 80 years.

The Diverse Range of Possible Cell Membrane Interactions with Substrates: Drug Delivery, Interfaces and Mobility.

The cell membrane has gained significant attention as a platform for the development of bio-inspired nanodevices due to its immune-evasive functionalities and copious bio-analogs. This review will examine several uses of cell membranes such as (i) therapeutic delivery carriers with or without substrates (i.e., nanoparticles and artificial polymers) that have enhanced efficiency regarding copious cargo loading and controlled release, (ii) exploiting nano-bio interfaces in membrane-coated particles from the macro- to the nanoscales, which would help resolve the biomedical issues involved in biological interfacing in the body, and (iii) its effects on the mobility of bio-moieties such as lipids and/or proteins in cell membranes, as discussed from a biophysical perspective. We anticipate that this review will influence both the development of novel anti-phagocytic delivery cargo and address biophysical problems in soft and complex cell membrane.

Effects of Membrane Defects and Polymer Hydrophobicity on Networking Kinetics of Vesicles.

The kinetics of clustering unilamellar vesicles induced by inverse Pluronics [poly(propylene oxide)m-poly(ethylene oxide)n-poly(propylene oxide)m, POm-EOn-POm] was investigated via experiments and molecular dynamic simulations. Two important factors for controlling the networking kinetics are the membrane defects, presumably located at the interfacial region between two lipid domains induced by acyl chain mismatch, and the polymer hydrophobicity. As expected, the clustering rate increases significantly with increasing bilayer defects on the membrane where the insertion of PPO is likely to take place because of the reduced energy barrier for the insertion of PO. The hydrophobic interaction between the PO blocks and membranes with the defects region dictates the "anchoring" kinetics, which is controlled by the association-dissociation of PO with the lipid membrane. As a result, the dependence of clustering rate on polymer concentration is strongly influenced by the hydrophobicity of the PO blocks. Nevertheless, longer PO blocks show stronger association with the membrane, resulting in faster consumption of the "active" sites made of these defect regions (causing mostly "invalid" insertions) with increasing polymer concentration, hence inhibiting the formation of large networking clusters, while shorter PO blocks undergo more frequent association with/dissociation from the defects, allowing continuous formation of larger clusters with increasing polymer concentration. This study provides important insights into how the organization and dynamics of a biomembrane influence its interaction with foreign amphiphilic molecules.

Nanoparticle puzzles and research opportunities that go beyond state of the art.

We present an overview of current progress and research challenges in the field of nanoparticle assembly, touching on the following topics: (1) historical perspective; (2) consideration of what is a nanoparticle; (3) contrast between nanoparticle self-assembly and top-down construction; (4) opportunities for nanoparticles with more intelligent sub-structures; (5) opportunities for nanoparticle systems cued to interact subtly in space and time. In this personal and subjective account, certain holy grails for nanoparticle science and technology are identified.

Unique effects of the chain lengths and anions of tetra-alkylammonium salts on quenching pyrene excimer.

Pyrene (Py) excimer, through its unique fluorescence quenching, exhibits high sensitivity and high selectivity in detecting specific electron-deficient molecules, providing a potential platform for sensing technology, optical switch, and probing hydrophobicity of molecular environment. In solution state, its quenching mechanism has been well-studied. However, there remain many unknown properties regarding the quenching mechanism of the solid-state Py excimer. In this paper, the effects of a series of tetra-alkylammonium salts (with a variety of chain lengths and anions) on Py excimer quenching are investigated to identify the controlling parameters of the fluorescence quenching in the binary system. Several experimental approaches including steady-state fluorescence spectroscopy, UV absorption, (13)C-nuclear magnetic resonance (NMR) spectra, X-ray diffraction, scanning electron microscopy, and time-dependent fluorescence decay are employed to seek for the fundamental understanding of the quenching mechanism. The result indicates a unique quenching effect of tetrabutylammonium cation on the pyrene excimer, and which is not observed in the other cations with different chain lengths (the same associated hexafluorophosphate anions). Meanwhile, hexafluorophosphate anion (in the presence of tetrabutylammonium) is able to effectively retain Py excimer fluorescence when the system is prepared by evaporating solvent at high temperature. It is also confirmed that dynamic quenching is involved in the process. Hydrophobic environment around Py molecules shows strong correlation with the formation of Py excimer. The knowledge obtained in this study provides the insights to how the interaction between salt and Py molecule affects the excimer fluorescence.

Association of tumor necrosis factor-α (TNF-α) promoter polymorphisms with overweight/obesity in a Korean population.

OBJECTIVE: Obesity is characterized by the activation of an inflammatory process leading to an increase in proinflammatory cytokines and adipokines. This study was designed to investigate the genetic association between tumor necrosis factor-α (TNF-α) polymorphisms and the risk of obesity in the Korean population. METHODS: Three single nucleotide polymorphisms [G-238A (rs361525), C-857T (rs1799724), and C-863A (rs1800630)] in the promoter region of TNF-α gene were analyzed in 123 control [body mass index (BMI) between 18 and 23] and 208 overweight/obese (BMI ≥ 23) subjects. RESULTS: The mean values of BMI in the control and overweight/obese groups were 21.1 ± 1.4 and 25.4 ± 1.8, respectively. Of the three SNPs, G-238A presented a significant association with overweight/obesity in the codominant model; the frequency of the G/G genotype in the overweight/obese group was 9.3% higher than that in the control group (P = 0.0046). When control and overweight/obesity subjects were combined together and analyzed, the level of high-density lipoprotein (HDL) was significantly higher in the C-857T C/C type SNP (P < 0.05). CONCLUSIONS: The results of this study suggest that the G allele of G-238A in TNF-α gene may be a risk factor for overweight/obesity in the Korean population and that the C allele of C-857T may be an protective factor in relation to the HDL level in the general Korean population.

Selective attention to pitch amid conflicting auditory information: context-coding and filtering strategies.

An auditory Eriksen-flanker task was used to study how conflicting information interferes with selective attention to task-relevant differences in pure-tone frequency. Across the observation intervals of the discrimination task, the relevant frequency differences between target tones were positive, but within an observation interval, they could appear to be small or negative relative to conflicting differences in flanker tones leading or trailing the target. Being correct required attending to the between-target and ignoring the target-flanker pitch relation (across and within observation-interval, respectively). The interference index was an elevation of conflict-laden frequency discrimination thresholds (FDTs), relative to no-conflict FDTs. When conflicting differences in frequency or level (but not in duration) trailed the relevant differences, interference (i.e., FDT elevation) was large and persistent, increased with the target-flanker time proximity, but decreased with extensive training. Interference occurs when the target-flanker pitch relation is more prominent than the one between targets, and the physical and/or perceptual effects of relevant and conflicting differences tend to cancel one another, as with the above conflicting differences. With untrained participants, the target-flanker pitch relation is most prominent in conditions fostering both the perceptual grouping of the target and flanker (e.g., close time proximity), and the recency and salience of the conflicting differences (e.g., trailing conflicting difference); conversely, by lessening such grouping and salience, prolonged training decreases or nullifies the interference. The interference observed herein does not arise because the relevant and the conflicting differences each prompt separate decisions or responses that are in mutual conflict; instead, it arises from the early-stage interaction between their perceptual effects.

Aging impairs the ability to ignore irrelevant information in frequency discrimination tasks.

Age effects on the ability to ignore irrelevant auditory information were studied using frequency discrimination threshold (FDT) tasks. FDTs were determined in an unmasked condition with target tones in isolation, and in two backward-masked conditions with a nontarget masking tone presented 20 to 240 ms after the target. One masked condition included irrelevant variability in the masker frequency, but the other did not. The no-variability condition yielded more masking in older than in young adults. Masker variability induced large FDT elevations in both groups; however, the improvement in FDTs with training was large in young but only minimal in older adults.