Habituation of changed acoustics properties after canal wall down mastoidectomy.

PURPOSE: Our objective is to evaluate the effect of habituation on the altered ear canal acoustics after canal wall down mastoidectomy. METHODS: A total of 11 participants with single sided dry cavities and normal contralateral ear canals with normal hearing thresholds were included in the study. Filtered sound fragments were created that simulate the different acoustic properties based on the participants Real Ear to Coupler Difference (RECD) of the cavity ear and the contralateral normal ear canal. These filtered sound fragments are presented to the cavity ear canal and the contralateral normal ear canal using inserts earphones. Participants performed a subjective quality assessment of the sound fragments using paired comparison with a seven-point scale (- 3 till + 3). RESULTS: Mean assessment of sound quality revealed the following results; naturalness of sounds of the cavity ear canal is 0.29 (± 1.41; ns) in favour of the filtered sound fragment of the normal ear canal. Mean assessment of sharpness of sounds in the cavity ear canal is 1.55 (± 1.21, p = 0.55) in favour of the filtered sound fragment of the normal ear canal. Overall preference in the cavity ear canal was in favour of the normal ear canal acoustics 0.72 (SD ± 1.54 p = 0.224). CONCLUSIONS: Patients with cavity ear canals seem to habituate to their altered ear canal acoustics. Transforming the ear canal acoustics of the cavity ear to normal ear canal acoustics seem to sharpen the incoming sounds. Overall assessment of quality of sound of the normal ear canal acoustics is better than the cavity acoustics.

Can we predict the altered subjective quality assessment of sound after ear canal surgery?

PURPOSE: To correlate the subjective quality assessment of ear canal acoustics of the participants to the objective measurement of the ear canal acoustics. The objective ear canal acoustics is the frequency-dependent modulation of soundwaves through the ear canal. Our second objective is to design a model to predict the subjective quality of sound based on the altered objective ear canal acoustics. METHODS: To determine the frequency-dependent modulation of the soundwaves the real-ear unaided gain (REUG) of the ear canal is measured. 40 participants with normal hearing were presented six simulated sound fragments representing the acoustic properties of six different ear canals (REUG). These six sound fragments were built based on the difference between these six REUGs and the average REUG of a normal adult ear canal. Subjective sound quality was evaluated using a VAS score and a paired comparison score. RESULTS: We found a strong correlation between the objective ear canal acoustics and the subjective assessment of the quality of sound (Spearman's rho-0.89). Our linear mixed VAS model for individual participants has an intercept of 95.6 and a slope of - 4.2 (p < 0.001). The paired comparison analysis endorsed our findings that an increased difference in REUG is predictive for a decreased quality assessment of ear canal acoustics. CONCLUSION: There is a strong correlation between the subjective evaluation of ear canal acoustics and the objective quality assessment of ear canal acoustics. Our models show that an increased difference in REUG predicts a decreased quality of ear canal acoustics.

The effects of a canalplasty and a canal wall reconstruction on perceived sound quality: preliminary results.

Objective of this work was to evaluate the perceptual effect of the acoustic properties before and after canalplasty and a reconstruction of the posterior canal wall in revision modified radical cavity surgery. This is a prospective study. Twenty normal hearing subjects were presented six simulated sound conditions representing the acoustic properties of six different ear canals (two normal ears, and two pre- and postoperative conditions). The six different real ear unaided responses of these ear canals were used to filter Dutch sentences, resulting in six simulated sound conditions. A seventh unfiltered 'reference' condition was used for comparison. Sound quality was evaluated using a seven-point paired comparison rating and a visual analogue scale (VAS). Significant differences in sound quality were found between all conditions and the pre-operative cavity condition (all p < 0.001) using both the paired comparison rating and VAS. No significant differences in VAS were found comparing the other conditions with each other. But when using the paired comparison rating, the post-operative canalplasty condition and both the pre and post-operative cavity conditions differed significantly from the other conditions. This explorative study shows that altering the acoustics of the OEAC after a canalplasty and a reconstruction of the ear canal in revision modified radical cavity surgery results in perceivable changes in sound quality. It is likely that these changes are primarily due to volume changes. To which extent these changes are of clinical importance remains to be determined.

Otoacoustic emissions in screening cleft lip and/or palate children for hearing loss--a feasibility study.

Patients with cleft lip and/or palate abnormalities are likely to suffer permanent conductive (PCHL) or sensorineural hearing loss (SNHL) due in part to the association with syndromes known to include PCHL or SNHL. The presence of otitis media, a nearly universal complication in these patients, makes identifying the hearing impaired in this population a challenge, since the detection of permanent hearing loss is made more difficult. This problem might be overcome by using click-evoked otoacoustic emissions (CEOAE's) shortly after birth. Twenty-one out of 28 newborns presented to the regional cleft palate team were eligible for CEOAE screening shortly after birth. Among these 21 infants, five had anomalies other than cleft lip and/or palate associated with an increased risk for hearing impairment. At the first CEOAE screening (ILO88 Emission Analyser, mean age 3 weeks, range 1-11 weeks) clear CEOAE's were present in all of the 18 ears of nine infants with isolated lip and/or jaw clefts. In 24 ears of 12 infants with palatal clefts, CEOAE's were present in only six ears (three infants), not demonstrable due to noisy registration in another six ears and absent in 12 ears despite a quiet registration. During follow-up of those who failed the first screening (18 ears, nine infants), normal hearing was found in 14 ears (seven infants) and sensorineural hearing loss was documented in four ears (two infants). CEOAE screening in infants with isolated lip and/or jaw clefts seems feasible and effective. In infants with palatal clefts an auditory brain stem screening might be more appropriate.

Dynamic response of a neonatal catheter-manometer system in situ.

OBJECTIVE: The purpose of this study was to develop, validate, and apply a flush-pulse method to determine the dynamic response of a neonatal catheter-manometer system (CMS) in situ. METHODS: In the flush-pulse method, the opened fast-flush valve of the CMS is closed; as a result, the fluid column in the CMS is impacted. This procedure can be done without affecting the net flow of infusion fluid. We validated the method in laboratory conditions by comparing 14 paired results obtained with this method to the results obtained using a generally accepted step-response method. The measurable values are the resonance frequency (fr) and the damping coefficient (delta). The analysis of the flush-pulse method in situ is complicated by the patient's blood pressure wave. A remedy for this problem that is based on the first derivative of the pressure signal has been developed. The flush-pulse method is applied 14 times in situ. RESULTS: In laboratory settings, the fr ranged from 12.5 to 64.0 Hz and delta ranged from 0.14 to 0.32. The correlation coefficient was 0.99 for fr and 0.91 for delta. We found four overdamped systems in situ (delta > 1). In other systems fr values between 8.5 and 41.0 Hz and delta values between 0.16 and 0.72 were observed. The dynamic response in situ appeared to deteriorate with time due to routine intensive care procedures. CONCLUSIONS: The flush-pulse method proved to be a valid test for determining the dynamic response. The results obtained in situ emphasize the need for a regular evaluation of the dynamic response of the neonatal CMS in order to assess the shape of the pressure wave.

Otoacoustic emissions in preterm infants: indications for cochlear development?

A longitudinal study of click-evoked otoacoustic emissions (CEOAEs) in 19 ears of 11 preterm infants--post-conceptional age (PCA): 30 to 39 weeks--resulted in a total of 90 CEOAE recordings. All but one of the 19 ears showed an increase of CEOAE amplitude at increasing PCA. The mean increase rate was 1.36 dB per week (dB/wk) for the left ears (n = 11, SD = 1.04 dB/wk), and 1.17 dB/wk for the right ears (n = 8, SD = 0,87 dB/wk). In six ears of three infants we were able to follow a total of 15 frequencies of spontaneous otoacoustic emissions (SOAEs). All of the monitored SOAE frequencies showed a positive shift in frequency with time, ranging from about 10 Hz/wk around 2000 Hz to about 50 Hz/wk around 5000 Hz. This increase of CEOAE amplitude and SOAE frequency indicates that OAE properties are not fully developed in preterm infants. Although the influence of middle ear properties cannot be excluded or proved, the observed SOAE frequency shift suggests development of the fine structures in the cochlea itself.

Click-evoked oto-acoustic emission measurement in preterm infants.

UNLABELLED: Click-evoked oto-acoustic emissions (CEOAE) are acoustic responses produced by the inner ear, reflecting functional auditory integrity. We studied both the success rate of the CEOAE method and the CEOAE presence in preterm infants during their stay at the Neonatal Intensive Care Unit (NICU), by analysis of the results of longitudinal CEOAE measurements in 19 preterm infants. The CEOAE method proved to be feasible in the majority of the population under study; the CEOAE measurement failed in 8% of the total of 226 attempts. Within the range of 30-40 weeks post-conceptional age (PCA) the CEOAE presence increased from about 50% to 80%. These results show the possible clinical application of CEOAE in a NICU for the monitoring of cochlear function during treatment of preterm infants. CONCLUSION: Bedside CEOAE measurement in preterm infants in a NICU is feasible at a PCA as low as 30 weeks.

Long-term and short-term variations in amplitude and frequency of spontaneous otoacoustic emissions in pre-term infants.

In pre-term infants, spontaneous otoacoustic emission (SOAE) frequencies show an upward shift with time. The present study aimed to monitor the SOAE amplitude variation during this frequency shift. A long-term observation of 87 SOAE frequencies from 18 pre-term infants yielded a positive frequency shift of 0.72 per cent per week, which was not accompanied by a simultaneous amplitude shift, as the mean variations in SOAE amplitude were practically zero. Furthermore, there was no relationship between the short-term SOAE amplitude variation and the infant's post-conceptional age. Only the absolute amount of SOAE amplitude variation seemed to grow with time. Comparison with induced variations in SOAE frequency argues against a middle ear influence on the SOAE frequency shift. In our view, the absence of any amplitude shift during the upward SOAE frequency shift further suggests cochlear development during the last period of gestation.

Frequency shift of individual spontaneous otoacoustic emissions in preterm infants.

In adults, spontaneous otoacoustic emissions (SOAE) have shown a considerable frequency stability. In preterm infants, however, the SOAE proved to show an apparent and consistent upward shift of frequency at increasing postconceptional age (PCA). In 25 ears of 14 preterm infants (PCA, 29.1-41.3 wk) a total of 66 SOAE frequencies were monitored, ranging from 1611 to 5774 Hz. All but one of the SOAE frequencies shifted toward higher frequency. The SOAE frequency shift rate in Hertz per week was proportionally constant relative to the SOAE frequency. The mean shift rate was 0.74 +/- 0.39%/wk. At increasing PCA, the SOAE frequency shift rate tended to slow down. A linear fit through the data predicted the SOAE frequency to stop at about 45-50-wk PCA. The frequency dependence and time course of the SOAE frequency shift strongly suggest cochlear maturation during the last period of gestation.