Kristi Oeding

Effectiveness of the Directional Microphone in the Baha® Divino™

BACKGROUND Patients with unilateral sensorineural hearing loss (USNHL) experience great difficulty listening to speech in noisy environments. A directional microphone (DM) could potentially improve speech recognition in this difficult listening environment. It is well known that DMs in behind-the-ear (BTE) and custom hearing aids can provide a greater signal-to-noise ratio (SNR) in comparison to an omnidirectional microphone (OM) to improve speech recognition in noise for persons with hearing impairment. Studies examining the DM in bone anchored auditory osseointegrated implants (Baha), however, have been mixed, with little to no benefit reported for the DM compared to an OM. PURPOSE The primary purpose of this study was to determine if there are statistically significant differences in the mean reception threshold for sentences (RTS in dB) in noise between the OM and DM in the Baha® Divino™. The RTS of these two microphone modes was measured utilizing two loudspeaker arrays (speech from 0° and noise from 180° or a diffuse eight-loudspeaker array) and with the better ear open or closed with an earmold impression and noise attenuating earmuff. Subjective benefit was assessed using the Abbreviated Profile of Hearing Aid Benefit (APHAB) to compare unaided and aided (Divino OM and DM combined) problem scores. RESEARCH DESIGN A repeated measures design was utilized, with each subject counterbalanced to each of the eight treatment levels for three independent variables: (1) microphone (OM and DM), (2) loudspeaker array (180° and diffuse), and (3) better ear (open and closed). STUDY SAMPLE Sixteen subjects with USNHL currently utilizing the Baha were recruited from Washington Universitys Center for Advanced Medicine and the surrounding area. DATA COLLECTION AND ANALYSIS Subjects were tested at the initial visit if they entered the study wearing the Divino or after at least four weeks of acclimatization to a loaner Divino. The RTS was determined utilizing Hearing in Noise Test (HINT) sentences in the R-Space™ system, and subjective benefit was determined utilizing the APHAB. A three-way repeated measures analysis of variance (ANOVA) and a paired samples t-test were utilized to analyze results of the HINT and APHAB, respectively. RESULTS Results revealed statistically significant differences within microphone (p < 0.001; directional advantage of 3.2 dB), loudspeaker array (p = 0.046; 180° advantage of 1.1 dB), and better ear conditions (p < 0.001; open ear advantage of 4.9 dB). Results from the APHAB revealed statistically and clinically significant benefit for the Divino relative to unaided on the subscales of Ease of Communication (EC) (p = 0.037), Background Noise (BN) (p < 0.001), and Reverberation (RV) (p = 0.005). CONCLUSIONS The Divinos DM provides a statistically significant improvement in speech recognition in noise compared to the OM for subjects with USNHL. Therefore, it is recommended that audiologists consider selecting a Baha with a DM to provide improved speech recognition performance in noisy listening environments.

Difference in Speech Recognition between a Default and Programmed Telecoil Program

BACKGROUND Hearing loss can lead to isolation and social withdrawal. The telephone oftentimes connects persons with hearing loss to society; however, telephone use is impeded by narrow bandwidth, loss of visual cues, electromagnetic interference, and inherent phone-line noise. In the past, research assessing telephone communication has consistently reported that switching from the microphone to a telecoil will typically result in the acoustic signal being discernibly softer. Properly used telecoils improve the signal-to-noise ratio (SNR), decrease the chance for acoustic feedback, and overcome the impact of distance and reverberation creating an opportunity for clearer telephone communication. Little research, however, has examined matching the telecoil frequency response to the prescribed target of the microphone frequency response (National Acoustics Laboratories, Non-Linear, version 1 [NAL-NL1]). PURPOSE The primary goal of this study was to determine if differences exist in speech recognition for sentences (AZ-BIO) and consonant-vowel nucleus-consonant monosyllabic words (CNC) between two telecoil conditions (default and programmed). A secondary goal was to determine if differences exist in speech recognition for sentences between male and female talkers. RESEARCH DESIGN A single-blinded randomized controlled trial. STUDY SAMPLE Twenty experienced adult hearing aid users with bilateral symmetric slight to severe sensorineural hearing loss were recruited from Washington University in St. Louis School of Medicine. In addition, ten normal-hearing participants were recruited to determine the presentation level of the speech stimuli for the hearing aid participants. DATA COLLECTION AND ANALYSIS Participants underwent real-ear measures to program the microphone frequency response of a receiver-in-the-canal hearing aid to NAL-NL1. Using the manufacturer software, one telecoil program remained as the manufacturer default and a second telecoil program was programmed so the sound pressure level for an inductive telephone simulator frequency response matching the microphones frequency response to obtain as close to a 0 dB relative simulated equivalent telephone sensitivity value as possible. Participants then completed speech recognition measures including AZ-BIO sentences (male and female talkers) and CNC monosyllabic words and phonemes, using both telecoil programs. A mixed model analysis was performed to examine if significant differences in speech recognition exist between the two conditions and speech stimuli. RESULTS Results revealed significant improvement in overall speech recognition for the programmed telecoil performance compared with default telecoil performance (p < 0.001). Also, improved performance in the programmed telecoil was reported with a male talker (p < 0.001) and performance for sentences compared with monosyllabic words (p < 0.001) or phonemes (p < 0.001). CONCLUSIONS The programmed telecoil condition revealed significant improvement in speech recognition for all speech stimuli conditions compared with the default telecoil (sentences, monosyllables, and phonemes). Additional improvement was observed in both telecoil conditions when the talker was male.

Evaluation of a BICROS System with a Directional Microphone in the Receiver and Transmitter.

BACKGROUND The bilateral contralateral routing of signals (BICROS) system has provided limited benefit for speech recognition in noise for patients with asymmetric sensorineural hearing loss, even when an automatic adaptive multichannel directional microphone (DM) is in the receiver (Rx) and an omnidirectional microphone (OM) is in the transmitter (Tx). A recent BICROS system was introduced that can be programmed with a DM in the Rx and an OM or a DM in the Tx. PURPOSE To examine if significant differences in sentence recognition in noise and subjective preferences are present between an OM and an adaptive broadband DM programmed in the Tx of a BICROS system with an automatic adaptive multichannel DM programmed in the Rx. RESEARCH DESIGN A randomized crossover single-blind design was used to assess differences between the OM and DM programmed in the Tx. STUDY SAMPLE Eighteen adult experienced BICROS system users were recruited. DATA COLLECTION AND ANALYSIS The BICROS system was fit using real-ear insertion gain measures. The Tx was programmed with an OM and a DM and the Rx was always programmed with an automatic adaptive multichannel DM. The order of microphone condition in the Tx was counterbalanced. Participants acclimatized to the BICROS system for 4 weeks and returned and completed the Abbreviated Profile of Hearing Aid Benefit (APHAB) for the respective microphone condition. The Tx was then programmed with the other microphone condition and participants acclimatized for another four weeks. At the final visit, the APHAB was completed for the respective microphone condition. After eight weeks of acclimatization, Hearing in Noise Test sentences were presented in the R-Space™ system with the Tx in either the OM or DM condition for three listening conditions: (1) speech from 90° to the Rx and noise from 0°, 90°, and 180° to the Tx (Sp Rx/N Tx), (2) speech from 90° to the Tx and noise from 0°, 90°, and 180° to the Rx (Sp Tx/N Rx), and (3) speech from 0° and noise from eight surrounding loudspeakers separated by 45° (diffuse). RESULTS A two-factor repeated measures analysis of variance revealed no significant differences between the OM and DM microphone conditions for Sp Rx/N Tx listening condition. A significant mean disadvantage of 1.9 dB (p < 0.01) was revealed for the DM compared to the OM for Sp Tx/N Rx listening condition and a mean advantage of 2.6 dB (p < 0.001) for the DM compared to the OM in a diffuse listening condition. There were no significant differences in the APHAB aided problem and resulting benefit scores between the OM and DM for the following subscales: ease of communication, background noise, reverberation, and aversiveness of sounds. CONCLUSIONS No significant differences were revealed between OM and DM for Sp Rx/N Tx. The DM performed significantly poorer than OM for the Sp Tx/N Rx listening condition. Results revealed significant benefit for the DM compared to OM for the diffuse listening condition. No significant differences were revealed between the OM and DM on the APHAB.

The Effect of a High Upper Input Limiting Level on Word Recognition in Noise, Sound Quality Preferences, and Subjective Ratings of Real-World Performance.

BACKGROUND One important factor that plays a role in front-end processing is the analog-to-digital converter within current hearing aids. The average input dynamic range of hearing aids is 96 dB SPL with an upper input limiting level (UILL) of 95-105 dB SPL. The UILL of standard hearing aids could distort loud signals, such as loud speech or music, which have root-mean-square values of 90 and 105 dB SPL with crest factors of 12 dB SPL to 14-20 dB SPL, respectively. This indicates that these loud sounds could create a distorted signal for patients when the input limiting level is reached. PURPOSE To examine if significant differences in word recognition in noise, sound quality preferences, and subjective ratings of real-world performance exist between conventional and high UILL hearing aids. RESEARCH DESIGN Words in noise and sound quality preferences were assessed using recordings on a Knowles Electronic Manikin for Acoustic Research with conventional and high UILL hearing aids, different microphone modes, and listening conditions. Participants wore the hearing aids for 2 mo and completed questionnaires on subjective performance. STUDY SAMPLE Ten adults with bilateral slight to moderately severe sensorineural hearing loss were recruited. RESULTS A four-factor repeated-measures analysis of variance (ANOVA) revealed significant differences between the conventional and high UILL across microphone modes and listening conditions for words in noise [F(2, 18) = 6.0; p < 0.05]. A three-factor repeated-measures ANOVA for sound quality preferences revealed a significant difference only for presentation level [F(1, 9) = 81.0; p < 0.001]. A one-factor ANOVA did not reveal significant differences between the conventional and high UILL on subjective ratings of real-world performance. CONCLUSIONS Word recognition and sound quality preferences revealed significant differences between the conventional and high UILL; however, there were no differences in subjective ratings of real-world performance. One participant preferred the conventional UILL, two the high UILL, and seven thought performance was equal, which may be due to the listening environments participants encountered, as evidenced by datalogging.

Differences in sensation level between the Widex Soundtracker and two real-ear analyzers.

BACKGROUND SoundTracker is an algorithm in Widexs Compass fitting software that could potentially be used to estimate a patients aided sensation level (SL). SoundTrackers accuracy of estimating a patients SL has never been verified in comparison to SL measured with commercially available real-ear analyzers. PURPOSE Determine whether statistically significant differences are present between the estimated SL of the Widex SoundTracker software application and the measured SL of the Audioscan Verifit and Frye 6500 real-ear analyzers at 500, 1000, 2000, and 4000 Hz. RESEARCH DESIGN This study used a randomized repeated measures design to determine differences in SL between SoundTracker and the Verifit and 6500. STUDY SAMPLE Ten subjects (N = 20 ears) were recruited who were experienced users of behind-the-ear hearing aids with conventional vented earmolds and had bilateral sensorineural hearing loss that was >30 dB HL below 1000 Hz and ≤70 dB HL to 4000 Hz. DATA COLLECTION AND ANALYSIS Real-ear in-situ thresholds (dB sound pressure level [SPL]) and real-ear aided responses (REAR; dB SPL) were measured at 500, 1000, 2000, and 4000 Hz to determine differences in SL between SoundTracker, Verifit, and 6500. A three-factor repeated measures analysis of variance (ANOVA) was utilized to determine differences between method (real-ear analyzers and SoundTracker), analyzer (Verifit and 6500), and frequency (500, 1000, 2000, and 4000 Hz). RESULTS Mean differences in measured SL for the Verifit and 6500 were ≤2 dB when compared to the estimated SL using SoundTracker. A statistically significant difference in SL was present between the Verifit and SoundTracker at 2000 Hz (p < 0.01), but no significant differences were present at 500, 1000, and 4000 Hz. A statistically significant difference in SL was present between the 6500 and SoundTracker at 4000 Hz (p < 0.01), but no significant differences were present at 500, 1000, and 2000 Hz. Mean differences in measured SL between the real-ear analyzers (difference of SoundTracker SL minus Verifit SL compared to the difference of SoundTracker SL minus 6500 SL) were ≤2 dB with a statistically significant difference present at 2000 Hz (p < 0.01), but no statistically significant differences were present at 500, 1000, or 4000 Hz. CONCLUSIONS Nearly 85% of the differences between the estimated SoundTracker SL and the measured SLs of the Verifit and 6500 were ≤2 dB. Despite some limitations of this study, SoundTracker could be useful as a counseling tool to illustrate to patients which sounds are audible or inaudible when unaided and aided.

Challenges in Fitting a Hearing Aid to a Severely Collapsed Ear Canal and Mixed Hearing Loss

BACKGROUND Collapsed ear canals typically occur when an outside force, such as a headset for audiometric testing, is present. However, when a collapsed ear canal occurs without external pressure, this creates a challenge not only for performing audiometric testing but also for coupling a hearing aid to the ear canal. PURPOSE This case report highlights the challenges associated with fitting a hearing aid on a patient with a severe anterior-posterior collapsed ear canal with a mixed hearing loss. RESEARCH DESIGN A 67-yr-old female originally presented to Washington University in St. Louis School of Medicine in 1996 with a long-standing history of bilateral otosclerosis. She had chronic ear infections in the right ear and a severely collapsed ear canal in the left ear and was fit with a bone anchored hearing aid (BAHA®) on the right side in 2003. However, benefit from the BAHA started to decrease due to changes in hearing, and a different hearing solution was needed. It was proposed that a hearing aid be fit to her collapsed left ear canal; however, trying to couple a hearing aid to the collapsed ear canal required unique noncustom earmold solutions. CONCLUSIONS This case study highlights some of the obstacles and potential solutions for coupling a hearing aid to a severely collapsed ear canal.