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D-D Noise and the NICU
The researcher below has agreed to actively monitor the "Discussion" pages associated with his research efforts for a three week period starting Monday, February 16, and ending Friday, March 6, 2009. In order to facilitate a discussion of this work, information has been posted below.
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Noise and the NICU
Interactions of noise and antibiotic treatment in neonatal mice
Role of working memory in reading for d/hh children
Assessing and limiting noise associated with neonatal intensive care (NICU) environments
Interactions of noise exposure, hyperoxia, and kanamycin in young CBA/J mice; (with AuD student Elizabeth Fernandez and KK Ohlemiller)
Effects of nonverbal working memory training in deaf/hard of hearing children on speech, language, and reading development (PhD student Michelle Gremp with C Conway)
William W. Clark, Ph.D. - Director, Program in Audiology and Communication Sciences
314 747 0101
Type of Research:
Varies depending upon the study. The work in the NICU environment is descriptive, and involves assessment of noise exposure in premature infants during air and ambulance transport to the hospital as well as ambient exposures in the NICU as well. An interventional educational program is being planned that is designed to reduce noise in the environment, and the levels will be assessed before and after the intervention.
The mouse study is an experimental multivalent design using an inbred strain CBA/J mice exposed to noise/ototoxic antimbiotics/hyperoxia alone or in combination.
The nonverbal working memory study is still in development, but can be best described as a mixed design including an assessment of tools for improving working memory and an assessment of a training program implementation using pre- and post-measures in d/hh children
NICU studies: children transported to the NICU at Childrens' Hospital in St. Louis via helicopter or ambulance; measures are not be made on the neonates themselves; rather assessments are determined of the noises to which they are exposed.
Mouse studies: Inbred strains of mice maintained in the Fay and Carl Simons Center for the Study of the Biology of Hearing and Deafness the Department of Otolaryngology, located within our building and studied in the laboratory of Dr. Kevin Ohlemiller.
Working memory study: children who are deaf or hard of hearing recruited from our cooperating schools, including three auditory oral schools in St. Louis, as well as the St. Louis Special School district.
This work is being completed in two phases. The first phase was designed to evaluate noise exposures associated with emergency transport of at-risk infants to Children's Hospital by helicopter or ambulance. Working with collaborator Mary Jude Weathers, we assessed noise exposures to children as they were transported to the hospital. To our surprise, we found that children transported by helicopter were occasionally exposed to very high levels of noise (up to 115 dBA) during the trip. The highest levels occurred just before the baby was placed inside the idling helicopter, often as the flight crew and nursing staff waited for the attending physician to give or receive last-minute instructions. In fact, the infant was the only occupant of the helicopter who did not wear hearing protection. An additional concern related to the practice of administering a prophylactic dose of an antibiotic to each infant just prior to the flight. Because it is known that antibiotics and noise interact synergistically in young animals, we worried that dosing preemies might increase the risk of sustaining a noise-induced hearing loss during the flight, and we considered asking physicians to refrain from the treatment for that reason. Unfortunately, although we would have liked to complete ABR and OAEs on the babies before and after transport, it was just not possible, so we designed a mouse study (see below).
The second phase of the NICU study is ongoing, and involves an assessment of all the noise sources within the NICU. We are making engineering and administrative changes designed to improve the environment by making it quieter for all, and we also are planning an educational program for the NICU staff and others who work or visit. The noise environment will be surveyed three times: initial; after engineering controls and administrative changes, and after educational program.
This study evolved from the NICU transport noise study above and was designed to test the hypothesis that pre-exposure to an ototoxic antibiotic (kanamycin) and or hyperoxia would exacerbate the effects of noise exposures, as measured by ABR thresholds in an inbred mouse strain (CBA/J). To our great surprise, the pre-dose of kanamycin completely protected the mice from any hearing loss caused by the noise exposure, or the combination of noise and hyperoxia. An initial report is available at:
. This is the Capstone publication of AuD student Elizabeth (Baum) Fernandez.
We are currently completing the histology studies of the cochleas, and a paper will be submitted for publication shortly. Continuing studies are underway assessing the boundary conditions for the protection effect, and addressing mechanisms by which a low dose of kanamycin might protect the premature cochlea from a subsequent noise injury. I think this study is an excellent example of the bi-directional nature of good translational research. In this case, a potential clinical recommendation we were ready to make- dropping the gentamycin prophylactic dose to avoid exacerbation- in fact has been reversed by good laboratory research. In addition to protecting against infection, the prophylactic dose also appears to protect against noise induced hearing loss.
Working memory study:
(Ph.D. thesis of my student, Michelle Gremp, working with Chris Conway at Saint Louis University).
Great variation exists in the abilities of hearing impaired children in the areas of speech perception and language abilities, and the reasons for these differences remain unclear. Pisoni has suggested that even though the brain and nervous system continue to develop in the absence of auditory stimulation, some cortical reorganization does occur. The resulting effect can be an atypical development of speech and language skills. A number of variables have been connected to these differences such as length of auditory deprivation and mode of communication, but there are still a number of more central cognitive and linguistic factors such as perception, attention, learning, and memory whose roles remain unclear. In a recent study Geers showed that both forward and backward digit spans of normal-hearing children were longer than those of hearing-impaired children. Findings also indicated that oral-only children have longer digit spans than children taught in a total communication setting, suggesting that working memory ability is not a fixed trait.
Studies indicate that forward digit spans reflect coding strategies which are related to phonological processing and verbal rehearsal mechanisms that are used to maintain information in short term memory before retrieval and output. Pisoni has suggested that differences in measures of working memory are associated with some milestones in speech and language acquisition.
Working memory refers to the controlled, limited capacity storage and attention component of memory. It includes the ability to retain and manipulate information and takes place in the prefrontal cortex. Measures of working memory have been shown to reliably predict performance in a number of cognitive and ability tasks such as reading comprehension, language comprehension, vocabulary learning, note-taking, writing and spelling.
Non-verbal working memory training tasks have been shown to improve measures of working memory and to generalize to non trained tasks requiring working memory in a number of groups including children with ADHD and stroke patients. Additionally, changes in cortical activity, as evidenced through MRI results, have been shown which raises the possibility of training-induced plasticity in the neural systems associated with working memory.
This study will determine whether working memory training with deaf and hard of hearing children can improve performance on non trained measures of working memory (both non verbal and verbal) and the implications for speech, language, and reading development.
URL for more information concerning posted research
Copies of all our Capstone and Independent study reports are available in a digital archive (dspace):
. The archive contains more than 800 reports from 1938- 2009. Also, descriptions of research in PACS and the Department of Otolaryngology at Washington University School of Medicine are available at:
Collaborative opportunities within posted research:
We invite discussion of collaborative opportunities for the listed studies as well as other opportunities
Grant RFP's opportunities related to posted research:
The studies of NICU noise and the related basic study of interaction between kanamycin and noise in neonatal mice and its implications should be of interest to the NIDCD. Kevin Ohlemiller and other colleagues in our research department will be developing additional studies around the basic finding of protection, and I suspect we may see a supplement.
The project on working memory is new, and we will be interested in feedback from others as it develops, including funding opportunities.
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