Diana C. Emanuel

The effect of otitis media and quality of daycare on children's language development

The objective of this study was to understand whether experience with otitis media (OM) early in life affected hearing levels of children as well as whether it affected the language development of children at 24 months of age. This study followed 67 daycare-attending infants for several years, performing weekly ear examinations by a nurse and physician and regular hearing testing. The Sequenced Inventory of Communication Development (SICD) was administered to all children at 24 months of age. Children were divided into chronic and non-chronic OM groups. In addition, half the children were in high quality daycare and half were in low quality daycare. Results suggested that children in low quality daycare with chronic OM performed more poorly on the expressive portion of the SICD in comparison to non-chronic children in low quality care. There were no differences on SICD performance for the OM groups in high quality care. Children with chronic OM also showed a hearing loss during episodes of OM while children with non-chronic or infrequent episodes did not show a hearing loss even during bouts of OM. Findings suggest that chronic OM may have adverse effects only when there is a hearing loss associated with OM and children are in a suboptimal environment, like low quality childcare.

Effect of static force on bone conduction hearing thresholds and comfort

Abstract Objective: To assess the effect of the static force of a bone vibrator on the results of bone conduction (BC) threshold measurements and comfort. Design: BC thresholds were determined for 40 participants using the standardized P-3333 headband and a leather adjustable headstrap with variable static forces (2.4, 3.4, 4.4, 5.4 N). Comfort ratings were examined using a five-point Likert scale. Results: Mean BC thresholds were within ± 2 dB across all conditions; differences may be considered small enough to be clinically insignificant. Participants experienced significantly greater discomfort with the P-3333 versus the adjustable headstrap. The mean static force of the P-3333 varied considerably and was higher in situ than the calibration standard of 5.4 N. Conclusions: The results suggest that future revisions of relevant international and national standards should address the use of an adjustable headstrap and a static force less than 5.4 N. Sumario Objetivo: Evaluar el efecto de la fuerza estática de un vibrador óseo en los resultados de las mediciones de los umbrales por conducción ósea (BC) y sobre la comodidad. Diseño: Se determinaron los umbrales BC en 40 participantes utilizando la diadema estandarizada P-3333 y una banda cefálica ajustable con fuerzas estáticas variables (2.4, 3.4, 4.4, 5.4 N). La calificación de la comodidad se examinó con una escala Likert de cinco puntos. Resultados: Los umbrales promedio estuvieron en los ± 2dB a través de todas las condiciones; las diferencias pueden ser consideradas lo suficientemente pequeñas para ser clínicamente insignificantes. Los participantes experimentaron una molestia mucho mayor con la P-3333 que con la banda cefálica ajustable. La fuerza estática de la P-3333 varió considerablemente y fue mayor in situ que en el estándar de calibración de 5.4 N. Conclusiones: Los resultados sugieren que las revisiones de los estándares internacionales y nacionales deben dirigir la atención al uso de las bandas cefálicas ajustables y una fuerza estática menor que 5.4 N.

Speech intelligibility and passive, level-dependent earplugs.

Objectives:Noise-induced hearing loss is one of the most common occupational diseases. Military personnel are at especially high risk due to the broad range of military noise hazards and the frequency of exposure. Hearing protectors are vital for this particular workforce, yet they can impede the ability to understand necessary communication in the field. Level-dependent hearing protectors are designed to protect the auditory system from the hazards of impulse noise, while preserving the ability to hear speech and other important auditory signals. The aim of this study was to evaluate the effect of two different passive, level-dependent earplugs (Combat Arms Earplugs; Sonic II Ear valves) on speech understanding of normal-hearing listeners in the presence of low-level background noise. The Combat Arms Earplug, developed specifically for use by military personnel, represented devices that attenuate impulse noise using small orifices and the Sonic II ear valve represented devices using an internal diaphragm. Design:This study used a repeated-measures experimental design. Four scrambled lists of each of the four Northwestern University No. 6 50-word lists were presented in random order at 65 dB SPL in the presence of quiet and two different types of background noise: multitalker and military vehicle noise; using three ear conditions: NP (open ear), CA (Combat Arms Earplugs), and SO (Sonic II earplugs); and three signal-to-noise ratios (SNRs): −10, 0, and +10 dB. Word recognition scores (WRSs) of 18 native English-speaking adults with normal hearing sensitivity were measured in all test conditions. The percentage of words correctly repeated was used to determine differences between the two different level-dependent devices, types of background noise, and SNRs. Results:Results showed a statistically significant increase in WRS as SNR increased from −10 to +10 dB. A repeated-measures analysis of variance for ear condition × noise × SNR indicated a significant main effect for SNR but not for type of noise or ear condition. A slight but significant interaction was found for SNR and ear condition. Conclusions:SNR had great impact on the ability of listeners to understand speech in the presence of background noise; however, the type of noise and the type of level-dependent device used did not. The results of the study support the notion that individuals potentially subjected to high-level impulse noise should be able to use level-dependent earplugs in low-level continuous noise without compromising speech understanding. More specifically, the passive, level-dependent earplugs currently used by military personnel do not appear to be detrimental to speech communication for listeners with normal hearing when the speech is at an average conversational level and the listener is actively attending to the signal.