The long-term goals of this project are to investigate changes in peripheral auditory function during maturation and aging and to investigate the relationship between these changes and concomitant changes in auditory perception. Specifically, we will: (1) define the time course for maturation and aging of distortion product otoacoustic emission (DPOAE) fine structure and the individual components comprising the distortion product, (2) define the time course for maturation and aging of the medial olivocochlear (MOC) reflex and (3) relate the observed changes in peripheral auditory physiology to changes in speech perception throughout the human lifespan. Past work has established that peripheral immaturities in the auditory system exist postnatally but the time course for maturation has not been defined, nor have the sources of this immaturity been fully specified. Experiments in this project will allow us to complete the maturational time line, examine the sources of immaturity by studying auditory function at multiple levels of the system, and consider how these changes in peripheral function impact communicative ability. The objectives will be achieved by implementing a novel approach that considers change in peripheral auditory function throughout the human lifespan as a continuum, including both maturational and aging processes.
The first aim will be addressed by measuring DPOAE fine structure to parse out the relative contribution from two basilar membrane sources: the DPOAE generator region and the DP characteristic frequency (CF) region. State-of-the-art swept-tone methodology will be used in eight age groups ranging from premature infants to elderly adults. There are currently no published studies of DPOAE fine structure in infants although this issue may be highly relevant to questions of cochlear maturation.
The second aim will be accomplished by implementing a DPOAE contralateral noise technique to measure MOC reflexes in the same eight age groups at three frequencies. This paradigm will take into account each subject's individual DPOAE fine structure pattern and record the MOC reflex at response peaks (maxima) only, to control for the relationship between DPOAE components during maturation and aging.
The third aim will be accomplished by measuring speech perception in noise along with the two previously described metrics of peripheral auditory function, in adolescent through elderly subjects. This experiment will examine the relationship between changes in the periphery and communicative ability and define the extent to which changes in auditory peripheral physiology throughout life can account for changes in perception. This work is relevant to hearing health and clinical practice because it will provide a normative framework for changes in auditory peripheral function from birth through old age. Furthermore, defining DPOAE fine structure in the pediatric population will help specify which cochlear regions are evaluated during routine DPOAE hearing tests and, thus, have the potential to increase accuracy of hearing diagnoses in children. Finally, this project will lead to a clearer understanding of how natural changes in auditory peripheral function contribute to diminishing speech perception in latter years and will help parse out peripheral versus central contributions to this decline. This work will provide a normative framework for natural changes in auditory peripheral function during maturation and aging and will help specify which cochlear regions (and frequencies) are actually assessed during a routine pediatric hearing evaluation using otoacoustic emissions. This information has the potential to increase the sophistication and accuracy of hearing evaluations and thus, of subsequent intervention. This work will also lead to an understanding of how natural, lifetime changes in auditory peripheral function contribute to diminishing speech perception during the latter decades of life and help parse out peripheral versus central contributions to this decline.
|Abdala, Carolina; Guérit, François; Luo, Ping et al. (2014) Distortion-product otoacoustic emission reflection-component delays and cochlear tuning: estimates from across the human lifespan. J Acoust Soc Am 135:1950-8|
|Abdala, Carolina; Dhar, Sumitrajit (2012) Maturation and aging of the human cochlea: a view through the DPOAE looking glass. J Assoc Res Otolaryngol 13:403-21|
|Garinis, Angela; Werner, Lynne; Abdala, Carolina (2011) The relationship between MOC reflex and masked threshold. Hear Res 282:128-37|
|Dhar, Sumitrajit; Rogers, Abigail; Abdala, Carolina (2011) Breaking away: violation of distortion emission phase-frequency invariance at low frequencies. J Acoust Soc Am 129:3115-22|
|Keefe, Douglas H; Abdala, Carolina (2011) Distortion-product otoacoustic-emission suppression tuning in human infants and adults using absorbed sound power. J Acoust Soc Am 129:EL108-13|
|Abdala, Carolina; Dhar, Sumitrajit; Mishra, Srikanta (2011) The breaking of cochlear scaling symmetry in human newborns and adults. J Acoust Soc Am 129:3104-14|
|Abdala, Carolina; Dhar, Sumitrajit (2010) Distortion product otoacoustic emission phase and component analysis in human newborns. J Acoust Soc Am 127:316-25|
|Abdala, Carolina; Dhar, Sumitrajit (2010) Differences in distortion product otoacoustic emission phase recorded from human neonates using two popular probes. J Acoust Soc Am 128:EL49-55|
|Abdala, Carolina; Mishra, Srikanta K; Williams, Tracy L (2009) Considering distortion product otoacoustic emission fine structure in measurements of the medial olivocochlear reflex. J Acoust Soc Am 125:1584-94|
|Deeter, Ryan; Abel, Rebekah; Calandruccio, Lauren et al. (2009) Contralateral acoustic stimulation alters the magnitude and phase of distortion product otoacoustic emissions. J Acoust Soc Am 126:2413-24|
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