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Hearing Aid Verification

Reference List

  1. Bagatto, M. P. (2001). Optimizing your recd measurements. Hearing Journal, 54(9), 32,34-36.
    Abstract: The proliferation of hearing screning programs has led to the identification of an increasing number of infants and children who require amplification. In an attempt to bring greater accuracy and objectivity to the challenging process of selecting and fitting amplification for the pediatric population, the real-ear-to-coupler difference (RECD) measurements procedure has been developed. Since infants and children have much smaller ears than adults, they bring considerable variation with them to the middle ear impendance and residual ear canal volume can significantly influence the adult RECD. Therefore, it is important to measure the RECD, on both adults and children, and utilize it in the amplification process whenever possible.

  2. Bagatto, M. P., Scollie, S. D., Seewald, R. C., Moodie, K. S., & Hoover, B. M. (2002). Real-ear-to-coupler difference predictions as a function of age for two coupling procedures. Journal of the American Academy of Audiology, 13(8), 407-415.
    Abstract: The predicted real-ear-to-coupler difference (RECD) values currently used in pediatric hearing instrument prescription methods are based on 12-month age range categories and were derived from measures using standard acoustic immittance probe tips. Consequently, the purpose of this study was to develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across the age continuum. To this end, RECD data were collected on 392 infants and children (141 with acoustic immittance tips, 251 with earmolds) to develop normative regression equations for use in deriving continuous age predictions of RECDs for foam/acoustic immittance tips and earmolds. Owing to the substantial between-subject variability observed in the data, the predictive equations of RECDs by age (in months) resulted in only gross estimates of RECD values (i.e., within +/- 4.4 dB for 95% of acoustic immittance tip measures; within +/- 5.4 dB in 95% of measures with custom earmolds) across frequency. Thus, it is concluded that the estimates derived from this study should not be used to replace the more precise individual RECD measurements. Relative to previously available normative RECD values for infants and young children, however, the estimates derived through this study provide somewhat more accurate predicted values for use under those circumstances for which individual RECD measurements cannot be made

  3. Feigin, J. A., Kopun, J. G., Stelmachowicz, P. G., & Gorga, M. P. (1989). Probe-tube microphone measures of ear-canal sound pressure levels in infants and children. Ear and Hearing, 10(4), 254-258.
    Abstract: Probe-tube microphone measures of ear-canal sound-pressure levels were obtained for 31 children under 5 years of age. These data were compared to similar measures from a group of 21 adults. The intrasubject variability was smallest for the frequency range from 750 to 3000 Hz and at no frequency did the mean standard deviation exceed 3 dB. Real ear to coupler differences for the children showed the same pattern as a function of frequency as for adults but were significantly larger. A systematic decrease in real ear to coupler differences was observed with increasing age between 1000 and 3000 Hz. An estimate of ear-canal volume did not appear to be a clinically useful predictor of real ear to coupler differences

  4. Hoover, B. M., Stelmachowicz, P. G., & Lewis, D. E. (2000). Effect of earmold fit on predicted real ear SPL using a real ear to coupler difference procedure. Ear and Hearing, 21(4), 310-317.
    OBJECTIVES: The goal of Experiment I was to quantify the SPL entering the ear canal via a secondary pathway created by a vent in the earmold and/or a slit leak around the earmold. The goal of Experiment II was to determine the validity of a real ear to coupler difference (RECD) procedure under conditions that are likely to produce errors (e.g., when hearing aid gain in the low frequencies is minimal and large negative RECD values occur as a result of venting or a loosely fitting earmold). DESIGN: In Experiment I, the SPL entering the ear via the secondary pathway was measured in 61 hearing-impaired children and 13 normal-hearing adults. In Experiment II, traditional probe microphone measures of real ear SPL were compared to the SPL predicted using the RECD procedure in five normal-hearing adults with loosely fitting earmolds. RESULTS: Results of Experiment I indicated that sound entered the ear canal unattenuated at 250 and 500 Hz, regardless of earmold fit, vent size, or subject age. In Experiment II, the largest differences between traditional probe microphone measures of SPL and predicted measures were noted when hearing aid gain was 0 dB and large negative RECD values were present. When hearing aid gain was minimal and the RECD was in the -10 to -22 dB range, predicted values underestimated the real ear SPL by an average of 14 dB. CONCLUSIONS: Although the results of this study apply only to a limited range of conditions found in clinical practice, in those cases, the errors may influence clinical decisions about the type of hearing aid fitted and the amount of gain provided. Potential solutions to this problem are discussed

  5. Martin, H. C., Westwood, G. F., & Bamford, J. M. (1996). Real ear to coupler differences in children having otitis media with effusion. British Journal of Audiology, 30, 71-78.
    Abstract: The aim of this study was to investigate the effects of otitis media with effusion (OME) on the 'real ear to coupler difference' (RECD) in children. RECDs are important in the procedures used for selection of appropriate amplification characteristics for children with permanent (usually sensorineural) hearing impairment. Subjects were 28 children aged between 4.6 and 7.6 years, 14 of whom had OME. There was no evidence of middle ear pathology in the remaining 14 who comprised the control group. All real-ear and coupler measures showed good test-retest repeatability at 4.0 kHz and below. The mean RECDs in frequency range 0.2-3.0 kHz were found to be up to 3.5 dB greater for the children having OME than for those without OME, although when statistically analysed only the differences in RECD at 1.0 kHz and 1.5 kHz were significant. Due to low correlation between the root mean square (RMS) sound pressure level (SPL) in the ear canal and ear canal volume, and low correlation between the subject's maximum RECD and ear canal volume, neither of these other variables could be used to predict an individual's RECD in this study. Large inter-subject variability was found, with a maximum standard deviation of 5.6 dB at 0.2 kHz, so this study greatly supports the need for individual RECD measurements to be made whenever possible, rather than using averaged transformation figures, par ticularly if the individual has OME

  6. Martin, H. C., Munro, K. J., & Langer, D. H. (1997). Real-ear to coupler differences in children with grommets. British Journal of Audiology, 31, 63-69.
    Abstract: Real-ear to coupler differences (RECDs) are important for the selection of appropriate amplification characteristics for hearing impaired children. The aim of this study was to investigate the effects of patent grommets on RECDs in children. Subjects were 32 children aged between 4 and 7 years, 16 had a patent grommet in one or both ears as confirmed by otoscopy and large equivalent ear canal volumes on tympanometry. There was no evidence of middle ear pathology in the remaining 16 who comprised the control group. All real-ear and coupler measures showed good test-retest repeatability across the whole frequency range. The mean difference in RECDs between the two groups in the frequency range 0.125-0.75 kHz was 15 dB. The differences in RECDs were statistically significant (P < 0.01) for all frequencies below 0.75 kHz. There was a strong correlation between the mean RECD and equivalent ear canal volume at all frequencies between 0.125 and 0.5 kHz, and a moderate correlation at 0.75 kHz. Large inter-subject variability was found, with a maximum standard deviation of 6.6 dB at 4.0 kHz. Therefore, this study supports the need for individual RECD measures to be made, particularly for subjects with grommets, rather than using averaged transformation figures. It suggests that more low frequency gain should be given to hearing aid users with patent grommets to overcome the redu ced SPL in the ear canal, due to leakage through the vented tympanic membrane

  7. Moodie, K. S., Seewald, R. C., & Sinclair, S. T. (1994). Procedure for predicting real-ear hearing aid performance in young children. American Journal of Audiology, 3, 23-31.

  8. Munro, K.J., and Buttfield, L.M. (2005). Comparison of real-ear to coupler difference values in the right and left ear of adults using three earmold configurations. Ear and Hearing, 26(3), 290-298.
    OBJECTIVE: The purpose of the study was to compare real-ear to coupler difference (RECD) values in the right and left ear of adults using three earmold configurations. DESIGN: The RECD was obtained from both ears of 18 normal hearing adults by subtracting the HA2 2-cc coupler response from the real-ear response using an ER-3A insert earphone and a swept pure tone on the Audioscan RM500 probe-tube microphone system. The measurements were made with a personal earmold, foam eartip, and oto-admittance tip. RESULTS: The mean difference between the right and left RECD was close to 0 dB for all earmold configurations and was not statistically significant on a repeated-measures analysis of variance (p > 0.05). In 90% of participants, the difference between ears was generally less than 3 dB at 0.5 to 4 kHz. CONCLUSIONS: Cooperative participants with non-occluding wax and normal middle ear function (on tympanometry) show small differences in RECD between the right and left ear, irrespective of the earmold configuration. The study has yet to be extended to the clinical setting where subject cooperation and earmold fit may differ from the present study. In the meantime, the findings from the present study indicate that where an RECD can be obtained from only one ear of a participant, it is probably best to use this to derive real-ear SPL of both ears instead of relying on average age appropriate corrections.

  9. Scollie, S. D., Steinberg, M. J., & Seewald, R. C. (2002). Evaluation of electroacoustic test signals II: development and cross-validation of correction factors. Ear and Hearing, 23(5), 488-498.
    OBJECTIVE: To develop and cross-validate corrections for improving the match between amplified speech levels and frequency response measurements with hearing aids. DESIGN: Previously published correction approaches were reviewed. Two regression-based corrections and two nonregression corrections were developed from an existing database of hearing aid responses measured with clinically available test signals and speech (Scollie & Seewald, 2002). Corrections were evaluated on a second database of digital hearing aid responses for test signals and speech. The second data set was constructed specifically to challenge three hypothesized threats to the robustness of the corrections. RESULTS: The error for each signal (corrected and uncorrected) was calculated. Correction procedures produced a significant improvement in the match between predicted and measured aided levels of speech. Inclusion of compression-related variables provided small but significant improvements. Results generalized to the second data set. CONCLUSIONS: Correction procedures may be applied to improve the match between aided test signal levels and aided levels of speech

  10. Scollie, S. D., & Seewald, R. C. (2002). Evaluation of electroacoustic test signals I: comparison with amplified speech. Ear and Hearing, 23(5), 477-487.
    OBJECTIVE: To evaluate the ability of clinical test signals to match the aided levels of real speech, across a range of hearing aid circuit types and strengths. DESIGN: Hearing aids (N = 41) were set to DSL targets for moderate, severe, and profound hearing losses. These hearing aids were tested with three test signals (Fonix Pure Tones, Fonix Composite Noise, and Audioscan Swept), as well as with running speech. The difference between the aided test signal and the aided speech was calculated. RESULTS: Accuracy of matches between aided test signals and aided speech levels depended on circuit type, signal type, and test level. CONCLUSIONS: Clinical test signals can more accurately match the aided levels of speech for all types of hearing aids if they are 1) speech-weighted and 2) temporally modulated. Matches were more accurate at low to moderate test levels (i.e., 50 to 70 dB SPL), and less accurate at high test levels (i.e., 85 dB SPL)

  11. Scollie, S. D., Seewald, R. C., Cornelisse, L. E., & Jenstad, L. M. (1998). Validity and repeatability of level-independent HL to SPL transforms. Ear and Hearing, 19, 407-413.
    OBJECTIVE: The purpose of this study was to evaluate the reliability and validity of the real ear to coupler difference (RECD) and the real ear to dial difference (REDD) in predicting real ear SPL (RESPL). DESIGN: The RESPL, RECD, and REDD were measured in the right ear of 24 normal-hearing subjects using probe microphone equipment and both insert and supra-aural earphones. The phones and probe tube were removed and replaced, and the RECD and REDD were remeasured. RESULTS: RESPL was predicted using the RECD for insert earphone data and the REDD for supra-aural earphone data. Reliability estimates were calculated as the difference between test and retest values for the RECD and REDD. Validity estimates were calculated as the difference between measured and predicted RESPL. Results indicate that the RECD and REDD have equal and high reliability and validity in predicting RESPL. CONCLUSIONS: It is concluded that the RECD and REDD may be used as level-independent HL to SPL transforms as a substitute for in situ audiometric procedures

  12. Scollie, S. D., & Seewald, R. C. (2002). Electroacoustic Verification Measures with Modern Hearing Instrument Technology. In R.C.Seewald & J. S. Gravel (Eds.), A sound foundation through early amplification 2001: Proceedings of the second international conference. (Vol. pp. 121-138). Great Britain: St. Edmundsbury Press.

  13. Seewald, R. Real ear to coupler difference measures: A strategy for electroacoustic fitting in young children. 1993.
    Ref Type: Unpublished Work

  14. Seewald, R. C. (1991). Hearing aid output limiting considerations for children. In J.A.Feigin & P. G. Stelmachowicz (Eds.), Pediatric amplification: Proceedings of the 1991 national conference (Vol. pp. 19-36). Omaha, NE: Boys Town National Research Hospital.

  15. Seewald, R. C., Hudson, S. P., Gagne, J. P., & Zelisko, D. L. (1992). Comparison of two methods for estimating the sensation level of amplified speech. Ear and Hearing, 13, 142-149.
    Abstract: Several methods have been proposed to estimate the sensation level (SL) at which children receive amplified speech from their hearing aids. The present study compared the SL estimates obtained with two such methods: (1) a sound field aided audiogram approach, and (2) an electroacoustic approach that incorporated the use of a probe tube microphone system (Seewald, Ross, & Stelmachowicz, 1987). Sound field aided thresholds were obtained for 13 hearing-impaired subjects at eight audiometric frequencies. For the electroacoustic approach, in situ thresholds were obtained using a button-type hearing aid receiver attached to a custom earmold. Real ear aided responses were measured using a 70 dB RMS speech-weighted composite noise signal (Frye, 1986). A comparison of the frequency-specific SL estimates derived from the two different methods revealed that the sound field aided audiogram approach yielded higher SL estimates for 74% of the individual comparisons. A detailed analysis of the findings obtained from two subjects suggested that when the results of the two methods did not agree, the differences were due to an interaction between signal level and the unique input/output characteristics of the subjects' hearing aids. A precautionary measure is suggested for those who wish to use sound field aided threshold data to estimate the SLs at which children receive amplified conve rsational speech

  16. Seewald, R. C., Moodie, K. S., Sinclair, S. T., & Scollie, S. D. (1999). Predictive validity of a procedure for pediatric hearing instrument fitting. American Journal of Audiology, 8, 143-152.
    Abstract: In 1994, Moodie, Seewald, & Sinclair described the development of a clinical procedure for predicting real-ear hearing instrument performance in young children. The purpose of the present study was to determine the validity of this procedure for predicting the real-ear aided gain (REAG) and real-ear saturation response (RESR) of hearing instruments worn by children. To this end, both the REAG and RESR were measured, through probe-microphone measures, and predicted, using the Moodie et al. procedure. The findings confirmed that the 2-cc coupler-based procedure, with individualized acoustic transforms, described by Moodie et al., resulted in highly accurate predictions of real-ear hearing instrument performance for both REAG and RESR at five test frequencies. The implications of these findings for the clinical fitting of hearing instruments in infants and young children are discussed.

  17. Seewald, R. C. (1999). Hearing aids for children. American Speech and Hearing Association, 41(3), 43-44.

  18. Sinclair, S. T., Beauchaine, K. L., Moodie, K. S., Feigin, J., Seewald, R. C., & Stelmachowicz, P. G. (1996). Repeatability of a real-ear-to-coupler difference procedure as a function of age. American Journal of Audiology, 5, 52-56.
    Abstract: For a given individual, the applicability of an average real-ear-to-coupler transfer function in the fitting of hearing aids is of limited utility, because the acoustical properties of individual ears may differ substantially from average transformation values (Feigin, Kopun, Stelmachowicz, & Gorga, 1989; Fikret-Pasa & Revit, 1992). It has been suggested, therefore, that individual real-ear-to-coupler difference (RECD) measures should be obtained whenever possible and applied within the fitting process (Hawkins, 1992; Nelson Barlow, Auslander, Rines, & Stelmachowicz, 1988). The purpose of this study was to investigate the repeatability of a specific RECD measurement procedure that has been developed for clinical application with young children (Moodie, Seewald, & Sinclair, 1994). The test-retest reliability of this procedure is reported for 10 adults and 90 children in the birth-to-7-year age range.

  19. Tharpe, A. M., Fino-Szumski, M. S., & Bess, F. H. (2001). Survey of hearing aid fitting practices for children with multiple impairments. American Journal of Audiology, 10(1), 32-40.
    Abstract: The fitting of amplification on young children with multiple impairments in addition to hearing loss is a challenge faced regularly by audiologists. However, very little has been published on this topic in the audiological literature. The purpose of this survey was to document hearing aid fitting practices for this population within the United States. Specifically, audiologists who regularly serve children were asked to complete a series of questions on their educational preparation and their hearing aid selection, fitting, and verification practices for children with multiple impairments. For purposes of this survey, multiple impairments included vision impairment, mental retardation, physical impairment, and autism spectrum disorders. Findings from this survey suggest that children with special needs in addition to hearing loss are typically fit in the same way and with the same type of amplification as those with hearing loss only. In addition, differences were noted in hearing aid selection, fitting, and verification practices across work settings. Future directions and research needs are suggested.

  20. Tharpe, A. M., Sladen, D., Huta, H. M., & McKinley, R. A. (2001). Practical considerations of real-ear-to-coupler difference measures in infants. American Journal of Audiology, 10(1), 41-49.
    Abstract: The purpose of this study was to investigate some of the practical issues surrounding the use of the real-ear-to-coupler difference (RECD) measure in infants in clinical settings. Twenty-two newborns were seen once a month during their first year of life for the purpose of obtaining RECD measurements. Two methods for obtaining the RECD were examined: the commonly used constant insertion depth method and the acoustic method. Differences between the results of the two methods were examined as well as test-retest reliability for each. Findings suggest that no compelling evidence exists to support the use of one of these methods over the other. Use of either method resulted in good test-retest reliability in the midfrequency range of the RECD, with poorer reliability on both ends of the frequency spectrum. Test-retest reliability decreased with increasing age for both methods. In addition, reliability of between-ear RECD values was examined. Between-ear measurements were most reliable in the midfrequency range, and reliability decreased slightly with increasing age

  21. Westwood, G. F., & Bamford, J. M. (1995). Probe-tube microphone measures with very young infants: Real ear to coupler differences and longitudinal changes in real ear unaided response. Ear and Hearing, 16, 263-273.
    OBJECTIVE: The feasibility and practicalities of performing probe-tube microphone measures with infants is addressed, as well as two aspects of acoustic functioning of infant ears: the real ear unaided response (REUR) and the real ear to coupler difference (RECD). DESIGN: Part 1 is a longitudinal study involving 12 infants. Serial measures of REUR were obtained over an 18-mo period. Infants were < or = 3 mo for the first test and < or = 21 mo at the last test visit. Practicalities of probe-tube microphone testing of unsedated infants and changes in the position (i.e., frequency) of the primary REUR peak were addressed. For part 2 of the project, 33 infants under 12 mo of age took part. A comparison of real ear hearing aid gain versus coupler gain was made. Test-retest differences for real ear aided response were estimated. RESULTS: Part 1 results indicate that probe-tube microphone measures in unsedated infants are feasible and show good within-subject repeatability. REUR measures for the more alert and mobile older subjects, as for the younger infants, showed an acceptably small degree of intersubject variability. The frequency of the primary REUR peak decreased during the first year of life, with a group mean of 2932 Hz reached at the end of the first year. However, thereafter, instead of stabilizing at around this value there was considerable fluctuation in the frequ ency of REUR peak. For Part 2, results a) confirmed the large RECD value for infants in the first year of life and b) showed a high degree of intersubject variability. Test retest measures of real ear aided response (REAR) gave values small enough to indicate the clear potential of probe-microphone use with infants during the hearing aid selection and fitting process. CONCLUSION: These findings should encourage attempts to carry out individual probe-tube microphone measurements with very young infants. They point to the need for infant hearing aid fitting procedures which involve such measurements to secure appropriate amplification

Prescriptive Fitting Strategies
Using Probe-Microphone Measures
Advantages of RECD measurements with infants and young children
Frequently Asked Questions