Diagnosis and Follow-up of Hearing Loss in Infants Three experts in pediatric audiology addressed “Diagnosis and Follow-up of Hearing Loss in Infants” as part of the keynote panel at the Audiology Convention at ASHA on Nov. 20. This was the third daily keynote address offered at the Convention. Coverage on the first two keynote addresses appeared in the ... ASHA Convention Coverage
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ASHA Convention Coverage  |   February 01, 2005
Diagnosis and Follow-up of Hearing Loss in Infants
Author Notes
  • Linda Vaughan, is ASHA’s director of audiology practice management. Contact her at lvaughan@asha.org.
    Linda Vaughan, is ASHA’s director of audiology practice management. Contact her at lvaughan@asha.org.×
Article Information
Hearing Disorders / ASHA Convention Coverage
ASHA Convention Coverage   |   February 01, 2005
Diagnosis and Follow-up of Hearing Loss in Infants
The ASHA Leader, February 2005, Vol. 10, 1-4. doi:10.1044/leader.ACC.10022005.1
The ASHA Leader, February 2005, Vol. 10, 1-4. doi:10.1044/leader.ACC.10022005.1
Three experts in pediatric audiology addressed “Diagnosis and Follow-up of Hearing Loss in Infants” as part of the keynote panel at the Audiology Convention at ASHA on Nov. 20. This was the third daily keynote address offered at the Convention. Coverage on the first two keynote addresses appeared in the Dec. 14, 2004 and Jan. 18, 2005 issues of The ASHA Leader.
ABR, ASSR, and CAEP
Barbara Cone-Wesson, associate professor in the department of speech and hearing sciences at the University of Arizona, addressed “ABR, ASSR, and CAEP-What We Have Today and Hope for Tomorrow.” The advent of universal newborn hearing screening and the goal of identification of hearing loss by 3 months of age has brought the need to scrutinize and investigate current diagnostic evaluation techniques. Cone-Wesson stated that in regard to identifying infants with hearing loss, “we are doing a good job, but we can do better.”
She said that the hearing assessment of the population of 0ÿ6 months of age must include electrophysiologic evaluations and middle ear assessment, including bone conduction ABR. Audiologists should consider the status of the ear canal, tympanic membrane, and middle ear function. Additionally, maturation and its effects need to be considered. For example, wave I latency is mature by 6 weeks, but wave V continues to decrease for 12ÿ18 months. She added, “ABR is not a hearing test. It is a test of neural synchrony and is affected by maturity.”
When performing ABR on infants, it is important to consider technical aspects such as transducers, Cone-Wesson said. They alter temporal characteristics and frequency content that will influence latency and amplitude, and calibration of transducers is essential. She added, “ABR thresholds calibrated in the ear canal can vary up to 20 dB, so do we need to consider real ear coupler differences when testing ABR thresholds as we do with amplification?”
Cone-Wesson noted the excellent correlation between tone burst ABR and behavioral thresholds, particularly with moderate to severe hearing losses in the high frequencies. But the question remains, “How do we report tone burst thresholds? Absolute? Calculated thresholds from regression formulae predictions? Calculated thresholds using correction factors?” Again she stressed that in relation to bone conduction ABR, “Remember three things-calibrate, calibrate, calibrate!”
With the emergence and wider spread use of Auditory Steady State Response (ASSR) the advantages of its robust detection algorithm and automation are demonstrated by the 15 years of data now available. But, she posed the question, “What is the best combination of stimulus parameters for performing ASSR?” Cone-Wesson noted that future research is needed to determine perceptual correlates of electrophysiologic measures, obtain performance-intensity function for speech feature discrimination, and develop ASSR I-O function using complex mixed modulation stimulus.
Visual Reinforcement Audiometry
The panel’s second speaker was Judith Widen, associate professor in the department of hearing and speech at the University of Kansas Medical Center, who presented on “Visual Reinforcement Audiometry: Art or Science?” Widen offered insights into the theoretical and practical aspects of operant conditioning and the development of a practical VRA (visual reinforcement audiometry) protocol.
“Interestingly enough, VRA/behavioral hearing evaluations have become the gold standard for identification of hearing loss,” Widen noted. This has provided the impetus for two large multi-site research projects-the NIDCD Identification of Hearing Impairment and the ATPM/CDC Efficacy of OAE/ABR in Identifying Hearing Loss-for which specific clinically applicable VRA test protocols were developed. The test protocols called for testing to be completed under earphones using a two-person team approach.
When questioned about overcoming the issue of earphone use on infants, Widen quoted Wes Wilson: “How do I get babies to wear earphones? I’m bigger than they are.” She cautioned audiologists to be aware of examiner bias and to utilize control trials to minimize this effect. Research indicated that hearing results obtained with VRA techniques correlated within 10 dB of results obtained with conditioned play or adult procedures. There was also good correlation with tympanometry results. These findings stand to confirm the need for development and implementation of standardized VRA test protocols.
Hearing Loss in Infants
Christine Yoshinaga-Itano, a researcher at the Marion Downs Hearing Center and professor at the University of Colorado, Boulder, spoke about “Current Approaches to Diagnosis and Follow-Up of Hearing Loss in Infants.” Yoshinaga-Itano stated that her current study in diagnosis of hearing loss in infants was fueled by the fact that “currently, no tools exist which evaluate the ability of infants with hearing loss to discriminate speech.”
Previous research has been restricted to speech discrimination in older children, children with severe to profound hearing loss, and normal hearing infants with simulated hearing loss. Her research was designed with the goal of developing protocols that measure speech discrimination in infants with hearing loss. Protocols that utilized visual reinforcement and behavioral observation techniques were described.
Demonstrated testing indicated conditioned responses that revealed discrimination of speech sounds in young infants. With evidence that discrimination ability can be evaluated in young infants, practical questions regarding appropriate amplification and its effects on developing speech, early intervention design based on an infant’s auditory profile, and cochlear implant candidacy may be answered.
Parental involvement in the evaluation of auditory behaviors is helpful. Yoshinaga-Itano recommended that parents be trained to systematically observe their child’s responses to environmental sounds and to stimulated speech sounds to assist in the development of the child’s auditory profile. This provides valuable information to the audiologist regarding amplification modifications.
The 2005 Audiology Convention at ASHA will be held Nov. 18–20 in San Diego, CA.
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February 2005
Volume 10, Issue 2