D. Robert Frisina

Word recognition in competing babble and the effects of age, temporal processing, and absolute sensitivity

This study was designed to clarify whether speech understanding in a fluctuating background is related to temporal processing as measured by the detection of gaps in noise bursts. Fifty adults with normal hearing or mild high-frequency hearing loss served as subjects. Gap detection thresholds were obtained using a three-interval, forced-choice paradigm. A 150-ms noise burst was used as the gap carrier with the gap placed close to carrier onset. A high-frequency masker without a temporal gap was gated on and off with the noise bursts. A continuous white-noise floor was present in the background. Word scores for the subjects were obtained at a presentation level of 55 dB HL in competing babble levels of 50, 55, and 60 dB HL. A repeated measures analysis of covariance of the word scores examined the effects of age, absolute sensitivity, and temporal sensitivity. The results of the analysis indicated that word scores in competing babble decreased significantly with increases in babble level, age, and gap detection thresholds. The effects of absolute sensitivity on word scores in competing babble were not significant. These results suggest that age and temporal processing influence speech understanding in fluctuating backgrounds in adults with normal hearing or mild high-frequency hearing loss.

Progestin negatively affects hearing in aged women

Female hormone influences on auditory system aging are not completely understood. Because of widespread clinical use of hormone replacement therapy (HRT), it is critical to understand HRT effects on sensory systems. The present study retrospectively analyzed and compared hearing abilities among 124 postmenopausal women taking HRT, treated with estrogen and progestin (E+P; n = 32), estrogen alone (E; n = 30), and a third [non-hormone replacement therapy (NHRT; n = 62)] control group. Subjects were 60–86 years old and were matched for age and health status. All had relatively healthy medical histories and no significant noise exposure, middle-ear problems, or major surgeries. Hearing tests included pure-tone audiometry, tympanometry, distortion-product otoacoustic emissions (DPOAEs), transient otoacoustic emissions, and the hearing-in-noise test (HINT). The HINT tests for speech perception in background noise, the major complaint of hearing-impaired persons. Pure-tone thresholds in both ears were elevated (poorer) for the E+P relative to the E and control groups. For DPOAEs, the E+P group presented with lower (worse) levels than the E and control groups, with significant differences for both ears. For the HINT results, the E+P group had poorer speech perception than the E and control groups across all background noise speaker locations and in quiet. These findings suggest that the presence of P as a component of HRT results in poorer hearing abilities in aged women taking HRT, affecting both the peripheral (ear) and central (brain) auditory systems, and it interferes with the perception of speech in background noise.

39 – Auditory Temporal Processing during Aging

This chapter presents results of a thematic interdisciplinary approach to characterizing and determining the neural bases of presbycusis. Research audiology, psychoacoustics, behavior and experimental psychology, neuroimaging and neurology, single-cell neurophysiology, neuroanatomy and neurochemistry, and evoked potential neurophysiology contributed to cross-project experiments in humans and animals. By using psychoacoustic and evoked potential neurophysiological paradigms such as forward and backward masking (gaps), interstimulus intervals and rates, and by manipulating naturally occurring pauses and voice-onset times in speech, we were able to gain insights into age-related slowing of central nervous system timing mechanisms. The peripheral auditory system with its extensive bank of filters is responsible for the spectral analysis of simple and complex environmental sounds. Thus, inner ear dysfunction is characterized principally and initially by deficiencies in frequency analysis and sensitivity. In contrast, most sounds, and especially suprathreshold complex sounds such as speech, vary over time. Therefore, measures of temporal resolution that can reflect the integrity of the central auditory system have become especially useful in our research seeking to determine the effects of age, per se, on hearing. Here we present results of our temporal resolution research utilizing human and animal subjects aimed at determining neural sites of hearing loss due to aging. This chapter also reinforces how findings from animal models can assist in understanding the human condition and thus lead to future interventions.

Effect of age on binaural speech intelligibility in normal hearing adults

Abstract Sentence perception performance, in quiet and in background noise, was measured in three groups of adult subjects categorized as young, middle-aged, and elderly. Pure tone audiometric thresholds, measures of inner ear function, obtained in all subjects were within the clinically normal hearing range. The primary purpose of this study was to determine the effect of age on speech perception: a secondary purpose was to determine if the speech recognition problem commonly reported in elderly subjects might be due to alterations at sites central to the peripheral nervous system inner ear. Standardized sentence lists were presented in free field conditions in order to invoke binaural hearing that occurs at the brainstem level, and to simulate everyday speech-in-noise listening conditions. The results indicated: (1) an age effect on speech perception performance in quiet and in noise backgrounds, (2) absolute pure tone thresholds conventionally obtained monaurally do not accurately predict suprathreshold speech perception performance in elderly subjects, and (3) by implication the listening problems of the elderly may be influenced by auditory processing changes upstream of the inner ear.

Higher serum aldosterone correlates with lower hearing thresholds: A possible protective hormone against presbycusis

Aldosterone hormone is a mineralocorticoid secreted by adrenal gland cortex and controls serum sodium (Na(+)) and potassium (K(+)) levels. Aldosterone has a stimulatory effect on expression of sodium-potassium ATPase (Na, K-ATPase) and sodium-potassium-chloride cotransporter (NKCC) in cell membranes. In the present investigation, the relation between serum aldosterone levels and age-related hearing loss (presbycusis) and the correlation between these levels versus the degree of presbycusis in humans were examined. Serum aldosterone concentrations were compared between normal hearing and presbycusic groups. Pure-tone audiometry, transient evoked otoacoustic emissions (TEOAE), hearing in noise test (HINT) and gap detection were tested for each subject and compared to the serum aldosterone levels. A highly significant difference between groups in serum aldosterone concentrations was found (p = 0.0003, t = 3.95, df = 45). Highly significant correlations between pure-tone thresholds in both right and left ears, and HINT scores versus serum aldosterone levels were also discovered. On the contrary, no significant correlations were seen in the case of TEOAEs and gap detection. We conclude that aldosterone hormone may have a protective effect on hearing in old age. This effect is more peripheral than central, appearing to affect inner hair cells more than outer hair cells.

Acknowledgments to Reviewers

Lee Altenberg Jeffrey Horn Boris Mitavskiy Helio Barbosa Christian Igel Sanaz Mostaghim Alwyn Barry Hisao Ishibuchi T. Murata Ramon Bejar Christian Jacob Olfa Nasraoui Sana Ben Hamida Kim Jingwon Boris Naujoks Peter Bentley Bryant Julstrom Martin Oates Peter Bosman Maarten Keijzer Pedro Oliviera Larry Bull Robert Keller Colin Reeves Mikhail Burtsev James Kennedy Mark Roberts Martin Butz Mathias Kern Frank Rotlauf Carlos Cotta Joshua Knowles Ramon Sagarna Bart Craenen Mario Koppen Kumara Sastry Bruce A. Draper Tim Kovacs Michele Sebag Rolf Drechsler Peter Krause Yann Semet Marc Ebner Gary Lamont Jonathan Shapiro Aniko Ekart Samuel Landau Jim Smith Michael Emmerich Marco Laumanns Bill Spears Fernando Esponda Xavier Llora Chris Stephens Jonathan Fieldsend Sushil L. Louis Susan Stepney Peter Fleming Jose Antonio Lozano Ponnuthurai Suganthan Simon Garrett Bernard Manderick Juergen Symanzik Ruxandra Gorunescu Ester Bernado Mansilla Keiki Takadama Jens Gottlieb Elena Marchiori KC Tan Garry Greenwood James Marshal Jon Timmis Steven Gustafson Martin C. Martin Jano Van Hemert Nikolaus Hansen Helmut Mayer Lyndon While Robert Heckendorn Nick McPhee Martin Zachariasen Francisco Herrera Juan J. Merelo Eckart Zitzler John Holmes

Methods for Studying Hearing Impairment and Auditory Problems of the Aged

Age-related hearing loss—presbycusis—is the foremost communication disorder of our elderly, and one of their top three chronic medical conditions. Currently, there are no cures for the sensorineural hearing loss and auditory processing problems that affect the majority of persons over age 60. We hope that increased basic research with animal models coupled with human clinical studies will lead to breakthrough translational studies aimed at prevention and eventual biomedical cure. The present chapter reviews a variety of effective procedures for measuring hearing loss as a function of age, including both classical and experimental paradigms. A theme of this exposition is that by utilizing key testing procedures, we can gain an understanding about how age and age-related ototoxic insults and conditions can affect either the cochlea (portion of the inner ear used for hearing) or the central auditory system (portions of the brain used for hearing).