Speech Recognition in Noise with Four Remote Microphone Technologies Krishna S. Rodemerk, Au.D. & Jason A. Galster, Ph.D. Starkey Hearing Technologies Test Conditions (24 Total) HINT 12 Feet Remote Microphone Only 1) Unaided (6 Feet and 12 Feet) 15 the hearing aid, overcoming the negative effects of talker distance, ambient noise, and 2) Omnidirectional Hearing Aid Microphone Only (6 Feet and 12 Feet; 3 different reverberation (Chisolm et al., 2007). Traditionally, remote microphone technology was most sets of hearing aids) Wireless Bluetooth® paired with near-field magnetic induction (NFMI) systems were evaluated at each visit: hearing aid only, remote microphone only and remote 2.4 GHz microphone plus hearing aid microphone. The HINT sessions were at least two weeks apart regular hearing aid wearers and none had remote microphone experience. All participants talker (p <0.001). HINT SNR-50 (dB) Box plot whiskers represent the 5th and 95th percentiles and the shaded box shows the 25th 0 * * * -10 participants received. However, it was unexpected that performance was similar when ic ic + 90 0 2. 4 M Hz GH z M M ic ic M oo th would decrease with activation of the hearing aid microphone (Boothroyd & Iglehart, 1998). We speculate that the noise levels used in this study were not sufficiently high to cause the HINT 6 Feet Remote Microphone Only Figure 4. HINT SNR-50 is shown as a function of microphone condition. Participants were seated 6 feet from the talker. The remote microphones were set such that there was equal contribution from the hearing aid microphone and the remote microphone. 15 HINT 12 Feet Remote Microphone + Hearing Aid Mic was presented from four speakers surrounding the participant (45°, 135°, 225°, and 315°). Participants were tested at 6 and 12 feet from the talker loudspeaker. The order of remote microphone conditions was counterbalanced across participants. presentations levels may reveal this effect. Though not discussed in detail here, the observed benefits were acoustically predictable in affects the quality and level of the transmitted signal. Successful use of any remote 10 microphone technology should include counseling on proper use and orientation. -5 * * -15 -20 0 * -5 * -10 * ic Chisolm, T.H., Noe, C.M., McArdle, R., & Abrams, H. (2007). Evidence for the use of hearing assistive technology by adults: The role of the FM system. Trends in Amplification, 11(2), 73-89 M ot e Re m -15 M ic + ic M GH z 2. 4 90 0 M Hz oo th M M ic ic + + HA HA M ic M ic HA M ic HA + FM Bl ue t 2. 4 GH z HA HA Hz M 0 90 O nl y O nl y O nl y HA Un ai de d -20 oo th /F M Figure 2. HINT SNR-50 is shown as a function of microphone condition. In the figure above, participants were seated 6 feet from the talker. The remote microphones were streaming only (no contribution from the hearing aid or environmental microphone). References Boothroyd, A., & Iglehart, F. (1998). Experiments with classroom FM amplification. Ear & Hearing, 19(3), 202-217. * GH z 2. 4 Hz M 0 90 O nl y O nl y ic M ot e Re m ot e Re m oo th FM Re m ot e M M ic ic O nl y O nl y O nl y HA GH z 2. 4 90 0 M Hz HA O nl y O nl y HA oo th /F M Un ai de d -25 5 Bl ue t * -10 * HINT SNR-50 (dB) HINT SNR-50 (dB) 0 conditions. Each condition was assessed one time using two lists (20 sentences for each condition). The speech was presented at 0° azimuth while continuous, speech shaped noise expected effect. Future studies using a test protocol that allows for higher noise nature. Of clinical note, proximity of the remote microphone to a talker's mouth greatly 15 Bl ue t only, remote microphone only and hearing aid microphone plus remote microphone 5 Bl ue t required for correct repetition of 50% of the sentences, was recorded for the hearing aid comparing remote microphone test conditions with and without the hearing aid microphone activated. Previous reports of this comparison suggest that remote microphone benefit + HA HA M M ic ic + + HA HA M M ic O nl y Bl ue t Bl ue t FM oo th /F M when compared to unaided and any hearing aid only condition (p <0.001). HA Un ai de d -20 prescribed targets in all test conditions. Verification of the remote microphone in-situ the accuracy of the listener’s response. The HINT SNR-50, or the signal-to-noise ratio when comparing remote microphone streaming, both with and without the hearing aid with all four of the tested remote microphone systems. * 10 presented at a fixed level (55 dB SPL) and the sentence levels were varied depending on the hearing aid microphone was introduced. -15 solid black line inside the box. Asterisks indicate significant improvement in HINT SNR-50 transparency was confirmed for all fittings, ensuring that the hearing aid output matched The Hearing in Noise Test (HINT) was used in its adaptive form during which the noise was participants were seated both 6 feet and 12 feet from the talker (p >0.05). As expected, distance between the participant and talker did not affect the benefit that the percentiles. Mean is shown as the dotted line and the median performance is the prescribed to age appropriate DSL v5.0 targets (Scollie et al., 2005). Remote microphone Test Material No difference was observed between remote microphone only performance when microphone enabled, to hearing aid only and unaided listening. This benefit was observed -5 GH z and 75 Real-ear measures were completed using an Audioscan Verifit. All hearing aids were puts. 6 feet and 12 feet from the talker (p <0.001). Participants in this study demonstrated significantly improved speech recognition in noise Verification phones with the remote microphone, the audio mixture was set to equal levels for both in- condition across all four remote microphone systems when participants were seated both The results of this study agree with previous reports of remote microphone benefit. 5 O nl y Results th pathway to the measurement. When the test condition combined the hearing aid micro- significantly increased speech recognition in noise when compared to the hearing aid only Discussion 2. 4 risks or benefits. output was done at test condition distances to allow for contribution of the direct acoustic Performance with the combination of remote microphones and hearing aid microphones 15 10 consent process that reviewed study methodology, their required involvement, and any used a standard size 13 tube. microphone systems when participants were seated both 6 feet and 12 feet from the HINT 6 Feet Remote Microphone + Hearing Aid Mic were financially reimbursed for their participation in the study and completed an informed system(s). All participants were fit with occluded, full shell custom earmolds; each earmold -20 -25 Figure 1. Five speaker array used for HINT testing. In the test set-up, the average Reverberation Time (RT60) was 0.4 seconds across frequency and the Direct to Reverberant Ratio was 6dB. sensorineural hearing loss participated in this study. Ten out of sixteen participants were bilateral set of hearing aids was paired with the respective, compatible remote microphone Performance with remote microphone streaming significantly increased speech recognition Performance was similar between three of the four remote microphone conditions when Sixteen adults aged 52 to 81 years (mean = 68.5 years) with mild to moderately-severe, and programming software from three hearing aid companies were used in this study. Each are discussed below. in noise when compared to the hearing aid only condition across all four remote Figure 3. HINT SNR-50 is shown as a function of microphone condition. In the figure above, participants were seated 12 feet from the talker. The remote microphones were streaming only (no contribution from the hearing aid or environmental microphone). Participants Commercially available behind-the-ear (BTE) hearing aids, remote microphone systems, * Post-hoc analyses used Tukey’s pairwise multiple comparison test, meaningful observations -15 to mitigate any learning effects. Methods Devices * * * -10 HA 900 MHz -5 remote microphone systems; remote microphone/hearing aid mix) Testing was done over two visits. Three microphone conditions for two remote microphone significant main effect of microphone condition: F(7,105) = 233.5, p <0.001 for six feet F(7,105) = 149.4, p <0.001 for 6 feet remote microphone plus hearing aid microphone and Maybe we could use this section as a lab design section and show an image of our speaker array? Hz Frequency Modulation (FM) 4) Remote Microphone Streaming + Hearing Aid Microphone (6 Feet and 12 Feet; 4 0 M protocol: systems) Four RMANOVAs were completed for the conditions shown in Figures 2-5; each showed a F(7,105) = 214.8, p <0.001 for 12 feet remote microphone plus hearing aid microphone. 0 microphone systems. Each of the four systems used a different wireless audio transmission Or O nl y This study documented speech recognition in noise with four commercially available remote 10 5 3) Remote Microphone Streaming Only (6 Feet and 12 Feet; 4 remote microphone Results remote microphone only; F(7, 105) = 255.2, p <0.001 for 12 feet remote microphone only; 90 often used in educational settings in the form of frequency modulated, or FM, systems. Would probably look nicer, but could be confusing? HA Remote microphones provide a direct audio input that results in a consistent input level to Results Bl Un ue ai to de ot h/ d FM HA 90 O nl 0 y M Hz HA O 2. nl 4 y G Hz FM HA Re O Bl nl m ue y ot to e ot M h ic Re O nl m 90 y ot 0 e M M Hz ic Re O nl m 2. y ot 4 e G M Hz ic Re O nl m y ot e M ic O nl y A remote microphone is a wireless transmitter that routes audio signals to a hearing aid. Methods HINT SNR-50 (dB) Introduction Wondering if we should put both HINT and ANL stats here and display both graphs to the right? Figure 5. HINT SNR-50 is shown as a function of microphone condition. Participants were seated 12 feet from the talker. The remote microphones were set such that there was equal audio contribution from the hearing aid microphone and the remote microphone. Lewis, M.S., Crandell, C.C., Valente, M., & Horn, J.E. (2004). Speech perception in noise: Directional microphones versus frequency modulation (FM) systems. Journal of the American Academy of Audiology, 15, 426-439. Nilsson M., Soli S.D., & Sullivan J.A. (1994). Development of the Hearing In Noise Test for the measurement of speech reception thresholds in quiet and in noise. Journal of the Acoustical Society of America, 95(2), 1085-99. Scollie, S., Seewald, R., Cornelisse, L., Moodie, S., Bagatto, M., et al. (2005). The Desired Sensation Level Multistage Input/Output Algorithm. Trends in Amplification 4(9), 159-197.
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