Objective Confirm that central auditory dysfunction may be a precursor to the onset of Alzheimer’s Disease (AD) Design Cohort study Setting Research study center Participants 274 volunteers from a dementia surveillance cohort were followed for up to 4 years after having complete audiometric assessment. 21 of the participants received a consensus diagnosis of AD after hearing testing. Intervention Three central auditory tests were performed: the Dichotic Sentence Identification, the Dichotic Digits, and the Synthetic Sentence Identification with Ipsilateral Competing Message. Main Outcome Measures A new diagnosis of Alzheimer’s disease using the National Institute of Neurological and Communicative Diseases and Stroke–Alzheimer’s Disease and Related Disorders Association criteria at a consensus conference Results The mean scores on each CAD test were significantly poorer in the incident dementia group. Cox proportional hazards models with age as the time-scale were used to estimate the hazard ratio for incident dementia based on CAD test results. After adjusting for educational level, the hazard ratio for incident dementia in people with severe CAD based on a Dichotic Sentence Identification in free report mode of <50% was 9.9 (95% C.I. 3.6, 26.7). Conclusions In these cases, CAD was a precursor to Alzheimer’s dementia. We recommend evaluating older adults complaining of hearing difficulty with CAD tests. Those with severe CAD should receive a modified rehabilitation program and be considered for referral for neurologic evaluation.

Structured Abstract Objectives To develop normative data for wideband middle-ear reflectance in a newborn hearing-screening population, and to compare test performance with 1-kHz tympanometry for prediction of OAE screening outcome. Design Wideband middle-ear reflectance (using both tone and chirp stimuli over 0.2 to 6 kHz), 1-kHz tympanometry, and distortion-product otoacoustic emissions (DPs) were measured in 324 infants at two test sites. Ears were categorized into DP-pass and DP-refer groups. Results Normative reflectance values were defined over various frequency regions for both tone and chirp stimuli in ambient pressure conditions, and for reflectance area indices (RAIs) integrated over various frequency ranges. Receiver-operating-characteristic (ROC) analyses showed that reflectance provides the best discriminability of DP status in frequency ranges involving 2 kHz, and greater discriminability of DP status than 1-kHz tympanometry. Repeated-measures analyses of variance (ANOVA) established that (a) there were significant differences in reflectance as a function of DP status and frequency, but not sex or ear; (b) tone and chirp stimulus reflectance values are essentially indistinguishable, and (c) newborns from two geographic sites had similar reflectance patterns above 1-kHz. Birth type and weight did not contribute to differences in reflectance. Conclusions Referrals in OAE-based infant hearing screening were strongly associated with increased wideband reflectance, suggesting middle-ear dysfunction at birth. Reflectance improved significantly over the first 4 days after birth with normalization of middle-ear function. Reflectance scores can be achieved within seconds using the same equipment used for OAE screening. Newborns with high reflectance scores at Stage I screening should be rescreened within a few hours to a few days, as most middle-ear problems are transient and resolve spontaneously. If reflectance and OAE are not passed upon Stage II screening, referral to an otologist for ear examination is suggested along with diagnostic testing. Newborns with normal reflectance and a refer result for the OAE screen should be referred immediately to an audiologist for diagnostic testing with threshold auditory brainstem response (ABR) due to higher risk for permanent hearing loss.

The purpose of this study was to examine wideband energy reflectance (ER) at ambient pressure in adults with a variety of middle-ear disorders. The ER results from 9 participants with middle-ear disorders and 1 participant with bilateral sensorineural hearing loss were compared with data provided by a group of 40 young adults with normal hearing sensitivity. Wideband ER results for the participant with sensorineural hearing loss followed the typical pattern of the data for young adults with normal hearing. For the 9 participants with middle-ear disorders (13 ears), the wideband ER responses fell outside the 5th to 95th percentile of the normative data for some portion of the frequency range in patterns that were distinct for otitis media with effusion, otosclerosis, ossicular discontinuity, and perforation of the tympanic membrane. Two ears with hypermobile 226-Hz tympanograms and normal hearing sensitivity had low-frequency ER patterns similar to that of a patient with ossicular discontinuity. One participant with negative middle-ear pressure had high ER in the low frequencies. This distinct ER pattern was similar to the patterns produced by participants with otosclerosis, demonstrating that a correction for middle ear pressure will be important for the clinical application of ER. Overall, the results suggest that wideband ER may be useful as a diagnostic tool in the assessment of middle-ear disorders.

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Objective-Determine the relation of age-related auditory processing dysfunction and executive functioning.Background-Central auditory dysfunction is common in Alzheimer's dementia but the mechanism is not established.

Wideband acoustic transfer function (ATF) measurements of energy reflectance (ER) and admittance magnitude (|Y|) were obtained at varying static ear-canal pressures in 4-, 12-, and 24-week-old infants and young adults. Developmental changes in wideband ATF measurements varied as a function of frequency. For frequencies from 0.25 to 0.75 kHz there was as much as a 30% change in mean ER and |Y| with changes in static ear-canal pressure between 4 and 24 weeks of age. From 0.75 to 2 kHz, the effects of pressure produced a small number of significant differences in ER and |Y| with age, suggestive of a developmentally stable frequency range. Between 2 and 6 kHz, there were differential effects of pressure for the youngest infants; negative pressures caused increased ER and |Y| and positive pressures caused decreased ER and |Y|; the magnitude of this effect decreased with age. Findings from this study demonstrate developmental differences in wideband tympanometric ATF measurements in 4-, 12- and 24-week-old infants and provide additional insight on the effects of static ear-canal pressure in the young infant's ear. The maturational effects shown in the experimental data are discussed in light of known age-related anatomical changes in the developing outer and middle ear.

Studies that have examined age effects in the human middle ear using either admittance measures at 220 or 660 Hz or multifrequency tympanometry from 200 to 2000 Hz have had conflicting results. Several studies have suggested an increase in admittance with age, while several others have suggested a decrease in admittance with age. A third group of studies found no significant age effect. This study examined 226 Hz tympanometry and wideband energy reflectance and impedance at ambient pressure in a group of 40 young adults and a group of 30 adults with age > or = 60 years. The groups did not differ in admittance measures of the middle ear at 226 Hz. However, significant age effects were found in wideband energy reflectance and impedance. In particular, in older adults there was a comparative decrease in reflectance from 800 to 2000 Hz but an increase near 4000 Hz. The results suggest a decrease in middle-ear stiffness with age. The findings of this study hold relevance for understanding the aging process in the auditory system, for the establishment of normative data for wideband energy reflectance, for the possibility of a conductive component to presbycusis, and for the interpretation of otoacoustic emission measurements.

Wideband measures of reflectance, admittance and power were successfully used to estimate acoustic reflex thresholds in seven participants. A reflex threshold test was devised based on the magnitude of the response shift in the presence of a contralateral activator, and the similarity of the response shift spectra across frequency between successive activator levels. Across all participants in the study, the new test yielded a more sensitive measure of the acoustic reflex threshold than the clinical method. This finding has both clinical and theoretical implications for the study of the acoustic reflex.