Optimizing Amplification for Infants and Young Children The success of universal newborn hearing screening programs has created a need for a well-defined scientifically based approach to the selection and fitting of hearing aids with this population. Current hearing-aid technology is complex, requiring many decisions during the fitting process. Studies with adults have shown large individual differences in ... Features
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Features  |   December 01, 2004
Optimizing Amplification for Infants and Young Children
Author Notes
  • Patricia Stelmachowicz, is the director of Audiological Services at Boys Town National Research Hospital in Omaha, Nebraska. Her research on optimization of amplification for infants and young children is funded by the National Institutes of Health (DC04300). Contact her at stelmach@boystown.org.
    Patricia Stelmachowicz, is the director of Audiological Services at Boys Town National Research Hospital in Omaha, Nebraska. Her research on optimization of amplification for infants and young children is funded by the National Institutes of Health (DC04300). Contact her at stelmach@boystown.org.×
Article Information
Development / Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Special Populations / Early Identification & Intervention / Research Issues, Methods & Evidence-Based Practice / Attention, Memory & Executive Functions / Features
Features   |   December 01, 2004
Optimizing Amplification for Infants and Young Children
The ASHA Leader, December 2004, Vol. 9, 31-32. doi:10.1044/leader.FTR5.09222004.31
The ASHA Leader, December 2004, Vol. 9, 31-32. doi:10.1044/leader.FTR5.09222004.31
The success of universal newborn hearing screening programs has created a need for a well-defined scientifically based approach to the selection and fitting of hearing aids with this population. Current hearing-aid technology is complex, requiring many decisions during the fitting process. Studies with adults have shown large individual differences in hearing-aid benefit, and subjective test techniques (often used to optimize the hearing aid fitting with adults) cannot be used with infants and young children.
In addition, the advanced signal-processing algorithms in use today were developed and refined using information from adults. In order for young children with hearing impairments (HI) to take maximum advantage of new technology, several unanswered questions need to be addressed. Studies are underway in the Hearing Aid Research Laboratory at Boys Town National Research Hospital to address these questions.
Do young children with HI require different amplification characteristics than adults with HI?
It has been argued that the acoustic needs of young children differ from those of adults with similar hearing losses. Because young children do not have the language structure or world knowledge to supplement communication, they will be less able to “fill in the blanks” under difficult listening conditions. Data from our laboratory suggest that young children with prelingual HI require a wider stimulus bandwidth than adults with HI in order to perceive and produce fricatives accurately. Additional studies addressing specific amplification needs of children with HI as a function of age and language skills will help to provide a theoretical framework for age-appropriate hearing-aid fitting algorithms in this population.
Can technological advances that are beneficial for adults be applied to children with equal success?
At present, some forms of advanced signal processing (e.g., wide dynamic range compression, directional microphones) have been shown to provide both objective and subjective benefit for adults. Although single-microphone noise-reduction schemes do not appear to improve speech perception in noise, listening comfort is enhanced. It is risky to assume, however, that these technologies will be beneficial for young children. For example, directional microphones are designed to improve the signal-to-noise ratio by attenuating sounds from the rear. As such, this type of processing may have a negative impact on children’s ability to “overhear” the conversations of others (a rich source of language input) and may pose a safety risk if warning signals cannot be heard. Single-microphone noise reduction schemes generally work by detecting the presence of noise and then attenuating both the noise and signal. Resultant changes to the signal that might not be noticeable to adults may be detrimental to infants and young children who are still developing speech and language skills. Over the next five years, we will conduct studies to determine the age at which various processing schemes may be applicable for children with HI.
Once amplification is initiated, how long will it take for a child to reach optimum performance?
The time course of acclimatization to amplification and/or changes in signal processing has not been studied in young HI children. A clear understanding of auditory learning and acclimatization in relation to the hearing-aid fitting process is necessary to determine the need to modify amplification, alter intervention strategies, and/or explore the possibility of subtle learning problems unrelated to hearing loss. We are beginning to investigate the issue of acclimatization in young children with HI.
What outcome measures should be used to measure the success of amplification?
A variety of outcome measures (e.g., speech perception, judged intelligibility, listening comfort) have been used to assess hearing-aid benefit in adults. Assessing device efficacy for infants and children with HI is much more complex. Formal speech perception tasks generally cannot be used with children under three years and gross measures of auditory awareness are not sensitive to differences between signal processing schemes. In a recent longitudinal study, we quantified phonological and lexical development in both children with normal hearing and children with HI to characterize the course and rate of early speech and language development from four months to five years of age. Such data are needed to determine if and when changes in intervention are warranted. This information also may provide a means by which to predict ultimate success from early learning landmarks. In future studies in our lab, speech perception, speech production, novel-word learning, and ease of listening will be used as outcome measures.
It is our hope that the results of these future studies in our laboratory will expand our basic knowledge of the acoustic needs of young children with hearing loss and facilitate the optimization of amplification in this population.
Research Team and Representative Publications
Core Research Team

Patricia G. Stelmachowicz, principal investigator Andrew Lotto, co-investigator Mary Pat Moeller, co-investigator Stephen Neely, co-investigator Dawna Lewis, research associate Brenda Hoover, research assistant

Representative Publications
Kortekaas, R., & Stelmachowicz, P. G. (2000). Bandwidth effects on children’s perception of the inflectional morpheme /s/: Acoustical measurements, auditory detection, and clarity rating. Journal of Speech, Language, and Hearing Research, 43, 645–660. [Article]
Kortekaas, R., & Stelmachowicz, P. G. (2000). Bandwidth effects on children’s perception of the inflectional morpheme /s/: Acoustical measurements, auditory detection, and clarity rating. Journal of Speech, Language, and Hearing Research, 43, 645–660. [Article] ×
Pittman, A. L., Stelmachowicz, P. G., Lewis, D. E., & Hoover, B. M. (2002). Influence of hearing loss on the perceptual strategies of children and adults. Journal of Speech, Language, and Hearing Research, 45, 1276–1284. [Article]
Pittman, A. L., Stelmachowicz, P. G., Lewis, D. E., & Hoover, B. M. (2002). Influence of hearing loss on the perceptual strategies of children and adults. Journal of Speech, Language, and Hearing Research, 45, 1276–1284. [Article] ×
Pittman, A. L., Stelmachowicz, P. G., Lewis, D. E., & Hoover, B. M. (2003). Spectral characteristics of speech at the ear: Implications for amplification in children. Journal of Speech, Language, and Hearing Research, 46, 649–657. [Article]
Pittman, A. L., Stelmachowicz, P. G., Lewis, D. E., & Hoover, B. M. (2003). Spectral characteristics of speech at the ear: Implications for amplification in children. Journal of Speech, Language, and Hearing Research, 46, 649–657. [Article] ×
Stelmachowicz, P. G., Hoover, B. M., Lewis, D. E., Kortekaas, R. W., & Pittman, A. L. (2000). The relationship between stimulus context, speech audibility, and perception for normal- and hearing-impaired children. Journal of Speech, Language, and Hearing Research, 43, 902–914. [Article]
Stelmachowicz, P. G., Hoover, B. M., Lewis, D. E., Kortekaas, R. W., & Pittman, A. L. (2000). The relationship between stimulus context, speech audibility, and perception for normal- and hearing-impaired children. Journal of Speech, Language, and Hearing Research, 43, 902–914. [Article] ×
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., & Lewis, D. E. (2001). Effect of stimulus bandwidth on the perception of /s/ in normal- and hearing-impaired children and adults. Journal of the Acoustical Society of America, 110, 2183–2190. [Article] [PubMed]
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., & Lewis, D. E. (2001). Effect of stimulus bandwidth on the perception of /s/ in normal- and hearing-impaired children and adults. Journal of the Acoustical Society of America, 110, 2183–2190. [Article] [PubMed]×
Stelmachowicz, P. G., Pittman, A.L., Hoover, B. M., & Lewis, D. L. (2002). Aided perception of /s/ and /z/ by hearing-impaired children. Ear and Hearing, 23, 316–324. [Article] [PubMed]
Stelmachowicz, P. G., Pittman, A.L., Hoover, B. M., & Lewis, D. L. (2002). Aided perception of /s/ and /z/ by hearing-impaired children. Ear and Hearing, 23, 316–324. [Article] [PubMed]×
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., & Lewis, D. L. (2004). Novel word learning in normal-hearing and hearing-impaired children. Ear and Hearing, 25, 47–56. [Article] [PubMed]
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., & Lewis, D. L. (2004). Novel word learning in normal-hearing and hearing-impaired children. Ear and Hearing, 25, 47–56. [Article] [PubMed]×
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., Lewis, D. L., & Moeller, M. P. (2004). The importance of high-frequency audibility in the speech and language development of children with hearing loss. Archives of Oto-Rhino-Larynogology, 130, 556–562.
Stelmachowicz, P. G., Pittman, A. L., Hoover, B. M., Lewis, D. L., & Moeller, M. P. (2004). The importance of high-frequency audibility in the speech and language development of children with hearing loss. Archives of Oto-Rhino-Larynogology, 130, 556–562.×
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December 2004
Volume 9, Issue 22