Page 34 - Spring2020

Boys Town Acoustics Research
the BTNRH participated in the planning and execution of a multicenter study to determine the accuracy of a combination of ABR and OAE measures in universal newborn hearing screening (Norton et al., 2000). The study resulted in the rec- ommendation of the two-stage screening process, starting with OAEs and followed by an ABR in those infants who fail the OAE screening, that is used in most universal newborn hearing screening programs today.
In the course of the multicenter newborn hearing screen- ing study, Douglas Keefe expressed an interest in moving to the BTNRH to pursue work on the clinical applications of his measures of middle ear transfer functions. Keefe had developed a system for making wideband reflectance measurements in human ears that is capable of assessing forward and reverse pressure contributions in the ear canal in response to clicks (Keefe, 1997). A pressurized version of the test resulted in a new and significantly improved ver- sion of tympanometry that provided reflectance data over a wide range of frequencies. Work at the BTNRH demonstrated that reflectance measurements were accurate in predicting conductive hearing loss in children classified as having otitis media with effusion (Keefe et al., 2012). Wideband reflec- tance measures were an important contribution to newborn hearing screening because fluid in the newborn middle ear accounts for a high percentage of the false positives encoun- tered in OAE and ABR screening. In collaboration with others, Keefe demonstrated this utility in a large-scale study of well babies before their hospital discharge (Sanford et al., 2009). The potential impact of these observations in terms of health-care costs cannot be overstated.
The advent of universal newborn hearing screening in the 1990s revolutionized pediatric audiology and aural habilita- tion by greatly reducing the age at which hearing loss was identified. In addition to the work by Gorga, Neely, and others on the methodology for hearing screening, others at the BTNRH were involved in groundbreaking research on the treatment and consequences of hearing loss in newly identi-
fied infants and children.
Patricia Stelmachowicz and colleagues demonstrated the importance of amplification at frequencies above 4 kHz for speech and language development in infants and children with hearing loss (Stelmachowicz et al., 2001, 2004). The data are shown in Figure 5. At that time, results suggested that high-frequency gain would not improve and might actually degrade speech recognition in adults with hearing loss, by far
Figure 5. Speech perception accuracy improves with bandwidth out to 9 kHz for female and child talkers. NH, normal hearing; HI, hearing impaired. From Stelmachowicz et al., 2001, Figure 3.
the largest segment of the hearing aid market. Little thought, however, had been given to the fact that high frequencies that were not transduced by hearing aids carried information about fricatives that marked plurals in English, an important factor in language development and in speech production by children with hearing loss. Work by Stelmachowicz and her colleagues had a major impact on hearing aid design and fit- ting for the pediatric population.
Mary Pat Moeller took the lead in longitudinal studies explor- ing the consequences of infant hearing loss on a range of child and family outcomes. She codirected with J. Bruce Tomblin a
34 | Acoustics Today | Spring 2020