Data Analysis

Data Analysis

Data Analysis

Introduction

Amplification has been utilized by patients for many years. There are various factors that have an impact on the success of these devices, one being proper fitting and programming of the aids. Hearing aids are often programmed to various prescriptions that utilize the individual's audiometric pure tone thresholds, most comfortable levels, and dynamic range to determine the best fit.

Real ear measurements are a good clinical tool to determine the response of the hearing aid in an individual's ear. Real ear measurements are used to ensure that the initial adjustment of the hearing aid is an adequate match to a target frequency response set from the fitting prescriptions (Dillon & Keidser, 2003). Mueller, Hawkins and Northern (1992), determined that real ear measurements were preferred over a 2cc coupler due the characteristics of an individuals ear and the change of response of a hearing aid once inserted into an individual's ear.

Participants and Pre-fitting Audiologic Testing

The test protocol was administered to 22 participants, 6 females and 16 males. Participants were all previous hearing aid users between the ages of 24 and 83 years and were recruited from the University of Northern Colorado Speech-Language Pathology and Audiology Clinic. After signing a letter of informed consent, audiometric evaluations and tympanograms were administered via a Grason Stadler GSI 61 audiometer and a Grason Stadler GSI 33 immittance bridge, respectively, calibrated to American National Standards Institute (ANSI, S3.6-1996) standards.

Otoscopy was performed to make sure there were no foreign objects or cerumen present in the ear canal which could affect results. Following otoscopy, an immittance test was performed to rule out any middle ear pathology. Pure tone air conduction testing was then performed from 250-8000Hz for ear. Bone conduction testing was performed at 500, 1000, 2000 and 4000 Hz. Frequency specific loudness discomfort levels (LDLs) were obtained for 500, 1500, and 3000 Hz for each ear. All participants displayed between a mild to moderately-severe, sensorineural hearing loss with hearing levels no better than 20 dBHL at 500 Hz and no worse than 75 dBHL at 3000 Hz. Symmetry between ears was within 15 dB for any given frequency. All participants displayed type A typanograms, verifying that a conductive component was not present. Using Margolis and Hunter's (2000) normative data, criteria for inclusion based on immittance testing were static admittance of .30 to 1.70, tympanic width (daPa) of 51-114, and a peak pressure of -100 daPa to +100 daPa. Table 1 shows the average hearing thresholds across participants in dBHL as a function of audiometric frequency.

Table 1

Average hearing threshold levels (in dBHL) for the right and left ears as function of audiometric frequency

250 Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz

Right Ear 34 36 44 55 61 70

Left Ear 28 34 39 52 60 69

Ear impressions were also obtained during the pre-fitting visit and custom molds were ordered.

Hearing Aid Fitting

At the second visit, each participant was binaurally fit with binaural Siemens Centra S VC behind-the-ear (BTE) hearing aids couple to the ear using vinyl, ...