Adaptive Directional Microphone Research Articles

Do Different Types of Microphones Affect Listening Effort in Cochlear Implant Recipients? A Pupillometry Study.

It is known that subjects with a cochlear implant (CI) need to exert more listening effort to achieve adequate speech recognition compared to normal hearing subjects. One tool for assessing listening effort is pupillometry. The aim of this study is to evaluate the effectiveness of adaptive directional microphones in reducing listening effort for CI recipients. We evaluated listening in noise and listening effort degree (by pupillometry) in eight bimodal subjects with three types of CI microphones and in three sound configurations. We found a correlation only between sound configurations and listening in noise score (p-value 0.0095). The evaluation of the microphone types shows worse scores in listening in noise with Opti Omni (+3.15 dB SNR) microphone than with Split Dir (+1.89 dB SNR) and Speech Omni (+1.43 dB SNR). No correlation was found between microphones and sound configurations and within the pupillometric data. Different types of microphones have different effects on the listening of CI patients. The difference in the orientation of the sound source is a factor that has an impact on the listening effort results. However, the pupillometry measurements do not significantly correlate with the different microphone types.

Speech Understanding and Subjective Listening Effort in Noise With Different OTEs and Sound Processing Technologies.

To determine speech reception thresholds (SRTs) in noise and subjective listening effort (LE) in cochlear implant (CI) recipients for application of three sound processing (SP) technologies with two off-the-ear (OTE) CI sound processors, a fixed moderately directional microphone (Standard), an adaptive directional microphone (Beam), and the spatial noise-reduction setting ForwardFocus, with the Kanso 2 (OTE2), and Beam with the Kanso (OTE1). Prospective repeated measures, within-subject design. Single tertiary-referral center. Twenty CI recipients with bilateral severe-to-profound sensorineural hearing loss. SRTs were assessed in two spatial configurations with frontal speech and noise from 90-180-270 degrees (S0N90-180-270) or from the CI side (S0NCI). SRTs were obtained for sentences of the Oldenburg sentence test presented in International Collegium of Rehabilitative Audiology (ICRA) noise ICRA5-250. LE for speech understanding in noise was evaluated in S0N90-180-270 and assessed in effort scale categorical units (ESCUs) by using Adaptive Categorical Listening Effort Scaling (ACALES). LEs at 5-dB signal-to-noise ratio (SNR) were calculated from fitted psychometric curves. With OTE2 in S0N90-180-270, SRT with ForwardFocus (-4.28 dB SNR) was better than with Beam (-3.13 dB SNR) and Standard (0.43 dB SNR). ForwardFocus showed lower LE5dB (2.61 ESCU) compared with Beam (4.60 ESCU) and Standard (5.32 ESCU). In a comparison of both OTEs in S0N90-180-270 regarding best-performing SP technology, ForwardFocus with OTE2 yielded a better SRT and better LE5dB than Beam with OTE1 (SRT: -1.70 dB SNR; LE5dB: 4.00 ESCU). With OTE2 in S0NCI, SRT was improved with ForwardFocus (-2.78 dB SNR) compared with Beam (-1.23 dB SNR) and Standard (1.83 dB SNR). With respect to SP technology and OTE, CI recipients experience best SRT and lowest LE in S0N90-180-270 when using ForwardFocus with OTE2. ACALES is feasible for assessing subjective LE in CI recipients.

Using the hearing in noise test (HINT) in the assessment of the performance of directional microphone

ObjectivesHearing in noise test (HINT) is used to evaluate and compare the performance of different hearing aid. This research was designed to compare the performance of a fixed directional microphone (FDM) and an automatic adaptive directional microphone (AADM) with different noise directions using aided Arabic HINT.MethodsControl group (CG): 20 normal peripheral hearing adults. Study group (SG): 40 adults with bilateral symmetrical sensorineural hearing loss. Arabic HINT was performed in three noise situations at 0°, 90°, and 270° azimuths for both groups. For SG, test was done in 4 conditions: condition (I), without hearing aid; condition (II), aided response with omnidirectional microphone; condition (III), aided response with FDM; and condition (IV), aided response with AADM.ResultsFor all azimuths, there was a statistically considerable difference between CG and SG in all conditions. Also, there was a statistically significant difference between SG conditions I and II and II and III. But no statistically significant difference was observed between conditions III and IV when the noise was at 90° and 270° azimuths.ConclusionAADM is the best choice of selection in hearing aid fitting, and it performs better in noise, especially when the noise and speech are in front of the patient.

Evaluation of Potential Benefits and Limitations of Noise-Management Technologies for Children with Hearing Aids.

Children with hearing loss frequently experience difficulty understanding speech in the presence of noise. Although remote microphone systems are likely to be the most effective solution to improve speech recognition in noise, the focus of this study centers on the evaluation of hearing aid noise management technologies including directional microphones, adaptive noise reduction (ANR), and frequency-gain shaping. These technologies can improve children's speech recognition, listening comfort, and/or sound quality in noise. However, individual contributions of these technologies as well as the effect of hearing aid microphone mode on localization abilities in children is unknown. The objectives of this study were to (1) compare children's speech recognition and subjective perceptions across five hearing aid noise management technology conditions and (2) compare localization abilities across three hearing aid microphone modes. A single-group, repeated measures design was used to evaluate performance differences and subjective ratings. Fourteen children with mild to moderately severe hearing loss. Children's sentence recognition, listening comfort, sound quality, and localization were assessed in a room with an eight-loudspeaker array. The use of adaptive directional microphone technology improves children's speech recognition in noise when the signal of interest arrives from the front and is spatially separated from the competing noise. In contrast, the use of adaptive directional microphone technology may result in a decrease in speech recognition in noise when the signal of interest arrives from behind. The use of a microphone mode that mimics the natural directivity of the unaided auricle provides a slight improvement in speech recognition in noise compared with omnidirectional use with limited decrement in speech recognition in noise when the signal of interest arrives from behind. The use of ANR and frequency-gain shaping provide no change in children's speech recognition in noise. The use of adaptive directional microphone technology, ANR, and frequency-gain shaping improve children's listening comfort, perceived ability to understand speech in noise, and overall listening experience. Children prefer to use each of these noise management technologies regardless of whether the signal of interest arrives from the front or from behind. The use of adaptive directional microphone technology does not result in a decrease in children's localization abilities when compared with the omnidirectional condition. The best localization performance occurred with use of the microphone mode that mimicked the directivity of the unaided auricle.

Improving Cochlear Implant Performance in the Wind Through Spectral Masking Release: A Multi-microphone and Multichannel Strategy.

Adopting the omnidirectional microphone (OMNI) mode and reducing low-frequency gain are the two most commonly used wind noise reduction strategies in hearing devices. The objective of this study was to compare the effectiveness of these two strategies on cochlear implant users' speech-understanding abilities and perceived sound quality in wind noise. We also examined the effectiveness of a new strategy that adopts the microphone mode with lower wind noise level in each frequency channel. A behind-the-ear digital hearing aid with multiple microphone modes was used to record testing materials for cochlear implant participants. It was adjusted to have linear amplification, flat frequency response when worn on a Knowles Electronic Manikin for Acoustic Research to remove the head-related transfer function of the manikin and to mimic typical microphone characteristics of hearing devices. Recordings of wind noise samples and hearing-in-noise test sentences were made when the hearing aid was programmed to four microphone modes, namely (1) OMNI; (2) adaptive directional microphone (ADM); (3) ADM with low-frequency roll-off; and (4) a combination of omnidirectional and directional microphone (COMBO). Wind noise samples were recorded in an acoustically treated wind tunnel from 0° to 360° in 10° increment at a wind velocity of 4.5, 9.0, and 13.5 m/s when the hearing aid was worn on the manikin. Two wind noise samples recorded at 90° and 300° head angles at the wind velocity of 9.0 m/s were chosen to take advantage of the spectral masking release effects of COMBO. The samples were then mixed with the sentences recorded using identical settings. Cochlear implant participants listened to the speech-in-wind testing materials and they repeated the sentences and compared overall sound quality preferences of different microphone modes using a paired-comparison categorical rating paradigm. The participants also rated their preferences of wind-only samples. COMBO yielded the highest speech recognition scores among the four microphone modes, and it was also preferred the most often, likely due to the reduction of spectral masking. The speech recognition scores generated using ADM with low-frequency roll-off were either equal to or lower than those obtained using ADM because gain reduction decreased not only the level of wind noise but also the low-frequency energy of speech. OMNI consistently yielded speech recognition scores lower than COMBO, and it was often rated as less preferable than other microphone modes, suggesting the conventional strategy to switch to the omnidirectional mode in the wind was undesirable. Neither adopting an OMNI nor reducing low-frequency gain generated higher speech recognition scores or higher sound quality ratings than COMBO. Adopting the microphone with lower wind noise level in different frequency channels can provide spectral masking release, and it is a more effective wind noise reduction strategy. The natural 6 dB/octave low-frequency roll-off of first-order directional microphones should be compensated when speech is present. Signal detection and decision rules for wind noise reduction applications are discussed in hearing devices with and without binaural transmission capability.

Perceived sound quality of different signal processing algorithms by cochlear implant listeners in real-world acoustic environments

Well-documented benefits of noise-reduction technologies in laboratories do not always yield a significant difference in real-world acoustic environments. Many possible reasons were proposed and studied to address this discrepancy. The purpose of this study was to examine the effectiveness of different noise reduction strategies for cochlear implants in real-world acoustic environments. Sixteen listeners were fit with hearing aid preprocessors with electrical outputs and cochlear implant speech processors receiving the electrical inputs. The preprocessors were programmed to 1) no noise reduction: omnidirectional microphone (OMNI), 2) moderate noise reduction: a combination of omnidirectional and adaptive directional microphone modes with modulation-based noise reduction (TRI+NR); and 3) maximum noise reduction: adaptive directional microphone in all frequency channels with NR (ADM+NR). Listeners listened to sentences in a noisy café, a noisy restaurant, and a quiet hotel lobby. They were instructed to rate the overall sound quality preference, ease of listening, speech intelligibility, and listening comfort of sentences using a paired-comparison categorical rating paradigm. Results indicate cochlear implant listeners had no microphone preference in quiet but they preferred adaptive directional microphones in noisy environments. The paired-comparison categorical rating paradigm is a viable means to evaluate the benefits of signal processing strategies in real-world acoustic environments.

The effects of adaptive directional microphone on auditory evoked cortical P300 response and speech performance in cochlear implant users

Objective: The aim of this study was to evaluate the possible benefits of an adaptive directional microphone in noise by using auditory P300 and speech recognition scores (SRSs) in cochlear implant subjects.Design: The P300 and speech recognition scores were obtained (a) in quiet with an omnidirectional microphone (Quiet OM), (b) in noise with an omnidirectional microphone (Noise OM) and (c) in noise with an adaptive directional microphone (Noise BEAM) to compare the microphone effects.Study sample: Thirty-five cochlear implant subjects (22.87 ± 1.30 years)Results: The latencies of the P2, N2 and P3 responses as the discrimination potentials were significantly prolonged in the Noise OM condition compared with those obtained in the Quiet OM and Noise BEAM conditions (p < 0.05). The latencies of all responses in the Quiet OM and Noise BEAM conditions were similarly obtained (p > 0.05). SRSs were significantly lower in the Noise OM condition than in the Quiet OM and Noise BEAM condition (p < 0.05).Conclusions: During noise, the adaptive directional microphone system provided a discrimination ability similar to that seen in quiet settings for cochlear implant users.

Asound reproduction system using wave field synthesis to simulate everyday listening conditions

Test procedures used in clinical routine are often not sufficiently accurate to evaluate the auditory benefit of hearing systems and the improvements brought by new signal preprocessing algorithms. The aim of the study was to realize and evaluate asound reproduction system for simulation of everyday listening conditions. Asound reproduction system was developed using 128loudspeakers. By appropriate superposition of the loudspeaker signals (so-called wave field synthesis), it is possible to create almost arbitrary everyday listening conditions in areproducible laboratory setting. Auditory scenes can be changed in real time. The sound reproduction system was mechanically evaluated by measuring the sound field with amicrophone array. To validate the system, speech reception thresholds (SRT) were measured in bilateral cochlear implant (CI) users in moving and diffuse noise conditions. Furthermore, the impact of different types of directional microphones on speech perception was assessed. With amoving noise source in the dorsal half-space, CI users showed significant SRT improvements by using directional microphones with higher directional sensitivity (2.5 dB improvement) as well as with adaptive directional sensitivity (8.5 dB). The benefit of adaptive directional microphones is reduced in environments with diffuse noise. Wave field synthesis is auseful tool to simulate everyday listening conditions in areproducible laboratory environment. This technique can complement established clinical methods to assess the benefit of ahearing device fitting or of signal preprocessing algorithms in dynamic listening conditions.

Impact of Microphone Configuration on Speech Perception of Cochlear Implant Users in Traffic Noise.

The aim of this study was to investigate the impact of microphone configuration and noise reduction algorithm on speech perception of cochlear implant (CI) users in a moving noise setup. Eleven CI users provided with Advanced Bionics implant systems participated in this study. All tests were conducted with three different microphone settings: (a) omnidirectional behind the ear (BTE), (b) inside the pinna (ITP), and (c) adaptive directional microphone (adaptive beamformer, ABF). Speech reception thresholds (SRTs) were measured using the Oldenburg sentence test in a moving noise source condition. Furthermore, the effect of a noise reduction algorithm on speech perception was measured in a condition with an additional static noise source. The ABF setting significantly improved SRT by 5.7 dB compared with the BTE microphone, and by 4.7 dB compared with the ITP microphone in the moving noise condition. In the presence of an additional static noise source, there was a significant improvement in SRT of 0.9 dB with the use of NR in addition to ABF. Adaptive beamforming can significantly improve speech perception in moving noise. Depending on the noise condition, the combination of ABF with NR can provide additional benefit.

Using Microphone Technology to Improve Speech Perception in Noise in Children with Cochlear Implants.

Cochlear implant (CI) users are affected more than their normal hearing (NH) peers by the negative consequences of background noise on speech understanding. Research has shown that adult CI users can improve their speech recognition in challenging listening environments by using dual-microphone beamformers, such as adaptive directional microphones (ADMs) and wireless remote microphones (RMs). The suitability of these microphone technologies for use in children with CIs is not well-understood nor widely accepted. To assess the benefit of ADM or RM technology on speech perception in background noise in children and adolescents with cochlear implants (CIs) with no previous or current use of ADM or RM. Mixed, repeated measures design. Twenty (20) children, ten (10) CI users (mean age 14.3 yrs) who used Advanced Bionics HiRes90K implants with research Naida processors, and ten (10) NH age-matched controls participated in this prospective study. CI users listened with an ear-canal level microphone, T-Mic (TM), an ADM, and a wireless RM at different audio-mixing ratios. Speech understanding with five microphone settings (TM 100%, ADM, RM + TM 50/50, RM + TM 75/25, RM 100%) was evaluated in quiet and in noise. Speech perception ability was measured using children's spondee words to obtain a speech recognition threshold for 80% accuracy (SRT80%) in 20-talker babble where the listener sat in a sound booth 1 m (3.28') from the target speech (front) and noise (behind) to test five microphone settings (TM 100%, ADM, RM + TM 50/50, RM + TM 75/25, RM 100%). Group performance-intensity functions were computed for each listening condition to show the effects of microphone configuration with respect to signal-to-noise ratio (SNR). A difference score (CI Group minus NH Group) was computed to show the effect of microphone technology at different SNRs relative to NH. Statistical analysis using a repeated-measures analysis of variance evaluated the effects of the microphone configurations on SRT80% and performance at SNRs. Between-groups analysis of variance was used to compare the CI group with the NH group. The speech recognition was significantly poorer for children with CI than children with NH in quiet and in noise when using the TM alone. Adding the ADM or RM provided a significant improvement in speech recognition for the CI group over use of the TM alone in noise (mean dB advantage ranged from 5.8 for ADM to 16 for RM100). When children with CI used the RM75 or RM100 in background babble, speech recognition was not statistically different from the group with NH. Speech recognition in noise performance improved with the use of ADM and RM100 or RM75 over TM-only for children with CIs. Alhough children with CI remain at a disadvantage as compared with NH children in quiet and more favorable SNRs, microphone technology can enhance performance for some children with CI to match that of NH peers in contexts with negative SNRs.

KORZYŚCI Z AKTUALIZACJI PROCESORA AUDIO U DOŚWIADCZONYCH UŻYTKOWNIKÓW AKTYWNEGO IMPLANTU UCHA ŚRODKOWEGO: ROZUMIENIE MOWY W HAŁASIE I SUBIEKTYWNA OCENA

BackgroundMicrophone directionality plays an important role in speech understanding in challenging acoustic environments. A new audio processor (AP) from Med-El, known as Samba, automatically detects and selects optimal settings depending on the listening situation. This clinical investigation evaluated speech understanding in noise and subjective benefit of an AP upgrade from the prior Amadé to the new Samba.Material and MethodsFourteen Vibrant Soundbridge users with at least 3 months experience with the Amadé AP received the new Samba AP. Speech recognition in quiet was measured using the Freiburger monosyllable test. Speech understanding in noise was assessed using the Oldenburger sentence test. Subjective benefit was determined with the Hearing Device Satisfaction Scale and the Abbreviated Profile of Hearing Aid Benefit.ResultsNo differences were detected in pure tone audiometry or speech recognition in quiet between the two audio processors. However, the new Samba AP performed significantly better in challenging noise situations: when speech came from the front and noise from the back, the signal-to-noise ratio (SNR) improved by 3.4 dB with the automatic mode of the Samba AP compared to the Amadé AP. When the sources of speech and noise were switched, a significant improvement of 1.8 dB SNR was observed. Based on the two questionnaires, subjective benefit in daily life and device satisfaction were comparable for the two APs.ConclusionsDue to its new features, the Samba AP gave significantly better results in challenging acoustical test situations. Even when the direction of background noise changed, the Samba AP performed better due to the new built-in adaptive directional microphones.

The use of cochlear's SCAN and wireless microphones to improve speech understanding in noise with the Nucleus6® CP900 processor

Objectives: The newest Nucleus CI processor, the CP900, has two new options to improve speech-in-noise perception: (1) use of an adaptive directional microphone (SCAN mode) and (2) wireless connection to MiniMic1 and MiniMic2 wireless remote microphones. Design: An analysis was made of the absolute and relative benefits of these technologies in a real-world mimicking test situation. Speech perception was tested using an adaptive speech-in-noise test (sentences-in-babble noise). In session A, SRTs were measured in three conditions: (1) Clinical Map, (2) SCAN and (3) MiniMic1. Each was assessed for three distances between speakers and CI recipient: 1 m, 2 m and 3 m. In session B, the benefit of the use of MiniMic2 was compared to benefit of MiniMic1 at 3 m. Study sample: A group of 13 adult CP900 recipients participated. Results: SCAN and MiniMic1 improved performance compared to the standard microphone with a median improvement in SRT of 2.7–3.9 dB for SCAN at 1 m and 3 m, respectively, and 4.7–10.9 dB for the MiniMic1. MiniMic1 improvements were significant. MiniMic2 showed an improvement in SRT of 22.2 dB compared to 10.0 dB for MiniMic1 (3 m). Conclusions: Digital wireless transmission systems (i.e. MiniMic) offer a statistically and clinically significant improvement in speech perception in challenging, realistic listening conditions.

Outer Hair Cell Damage: A Completely Different Listening Experience

Outer Hair Cell Damage: A Completely Different Listening Experience

Should All Deaf Children Learn Sign Language?

Should All Deaf Children Learn Sign Language?

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

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. 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. A randomized crossover single-blind design was used to assess differences between the OM and DM programmed in the Tx. Eighteen adult experienced BICROS system users were recruited. 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). 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. 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.

From My Perspective: Thriving in the New Audiology Frontier

From My Perspective: Thriving in the New Audiology Frontier

The Effectiveness of the Directional Microphone in the Oticon Medical Ponto Pro in Participants with Unilateral Sensorineural Hearing Loss

Current bone anchored hearing solutions (BAHSs) have incorporated automatic adaptive multichannel directional microphones (DMs). Previous fixed single-channel hypercardioid DMs in BAHSs have provided benefit in a diffuse listening environment, but little data are available on the performance of adaptive multichannel DMs in BAHSs for persons with unilateral sensorineural hearing loss (USNHL). The primary goal was to determine if statistically significant differences existed in the mean Reception Threshold for Sentences (RTS in dB) in diffuse uncorrelated restaurant noise between unaided, an omnidirectional microphone (OM), split DM (SDM), and full DM (FDM) in the Oticon Medical Ponto Pro. A second goal was to assess subjective benefit using the Abbreviated Profile of Hearing Aid Benefit (APHAB) comparing the Ponto Pro to the participant's current BAHS, and the Ponto Pro and participant's own BAHS to unaided. The third goal was to compare RTS data of the Ponto Pro to data from an identical study examining Cochlear Americas' Divino. A randomized repeated measures, single blind design was used to measure an RTS for each participant for unaided, OM, SDM, and FDM. Fifteen BAHS users with USNHL were recruited from Washington University in St. Louis and the surrounding area. The Ponto Pro was fit by measuring in-situ bone conduction thresholds and was worn for 4 wk. An RTS was obtained utilizing Hearing in Noise Test (HINT) sentences in uncorrelated restaurant noise from an eight loudspeaker array, and subjective benefit was determined utilizing the APHAB. Analysis of variance (ANOVA) was used to analyze the results of the Ponto Pro HINT and APHAB data, and comparisons between the Ponto Pro and previous Divino data. No statistically significant differences existed in mean RTS between unaided, the Ponto Pro's OM, SDM, or FDM (p = 0.10). The Ponto Pro provided statistically significant benefit for the Background Noise (BN) (p < 0.01) and Reverberation (RV) (p < 0.05) subscales compared to the participant's own BAHS. The Ponto Pro (Ease of Communication [EC] [p < 0.01], BN [p < 0.001], and RV [p < 0.01] subscales) and participant's own BAHS (BN [p < 0.01] and RV [p < 0.01] subscales) overall provided statistically significant benefit compared to unaided. Clinically significant benefit of 5% was present for the Ponto Pro compared to the participant's own BAHS and 10% for the Ponto Pro and the participant's own BAHS compared to unaided. The Ponto Pro's OM (p = 0.05), SDM (p = 0.05), and FDM (p < 0.01) were statistically significantly better than the Divino's OM. No significant differences existed between the Ponto Pro's OM, SDM, and FDM compared to the Divino's DM. No statistically significant differences existed between unaided, OM, SDM, or FDM. Participants preferred the Ponto Pro compared to the participant's own BAHS and the Ponto Pro and participant's own BAHS compared to unaided. The RTS of the Ponto Pro's adaptive multichannel DM was similar to the Divino's fixed hypercardioid DM, but the Ponto Pro's OM was statistically significantly better than the Divino's OM.

The Effect of Hearing Aid Technologies on Listening in an Automobile

Communication while traveling in an automobile often is very difficult for hearing aid users. This is because the automobile/road noise level is usually high, and listeners/drivers often do not have access to visual cues. Since the talker of interest usually is not located in front of the listener/driver, conventional directional processing that places the directivity beam toward the listener's front may not be helpful and, in fact, could have a negative impact on speech recognition (when compared to omnidirectional processing). Recently, technologies have become available in commercial hearing aids that are designed to improve speech recognition and/or listening effort in noisy conditions where talkers are located behind or beside the listener. These technologies include (1) a directional microphone system that uses a backward-facing directivity pattern (Back-DIR processing), (2) a technology that transmits audio signals from the ear with the better signal-to-noise ratio (SNR) to the ear with the poorer SNR (Side-Transmission processing), and (3) a signal processing scheme that suppresses the noise at the ear with the poorer SNR (Side-Suppression processing). The purpose of the current study was to determine the effect of (1) conventional directional microphones and (2) newer signal processing schemes (Back-DIR, Side-Transmission, and Side-Suppression) on listener's speech recognition performance and preference for communication in a traveling automobile. A single-blinded, repeated-measures design was used. Twenty-five adults with bilateral symmetrical sensorineural hearing loss aged 44 through 84 yr participated in the study. The automobile/road noise and sentences of the Connected Speech Test (CST) were recorded through hearing aids in a standard van moving at a speed of 70 mph on a paved highway. The hearing aids were programmed to omnidirectional microphone, conventional adaptive directional microphone, and the three newer schemes. CST sentences were presented from the side and back of the hearing aids, which were placed on the ears of a manikin. The recorded stimuli were presented to listeners via earphones in a sound-treated booth to assess speech recognition performance and preference with each programmed condition. Compared to omnidirectional microphones, conventional adaptive directional processing had a detrimental effect on speech recognition when speech was presented from the back or side of the listener. Back-DIR and Side-Transmission processing improved speech recognition performance (relative to both omnidirectional and adaptive directional processing) when speech was from the back and side, respectively. The performance with Side-Suppression processing was better than with adaptive directional processing when speech was from the side. The participants' preferences for a given processing scheme were generally consistent with speech recognition results. The finding that performance with adaptive directional processing was poorer than with omnidirectional microphones demonstrates the importance of selecting the correct microphone technology for different listening situations. The results also suggest the feasibility of using hearing aid technologies to provide a better listening experience for hearing aid users in automobiles.

Individual Variability in Benefit from Fixed and Adaptive Directional Microphones

This study aimed to document improvements in speech recognition when listening through fixed or adaptive directional microphone arrays relative to listening through omnidirectional microphone arrays in a variety of near-field noise conditions. Twelve participants with mild to severe hearing loss were recruited. Data were analyzed in a manner to facilitate discussion of both group and individual performance. The activation of directional microphones significantly improved speech recognition in all listening conditions when compared to omnidirectional listening conditions. Significant differences in speech recognition performance were not observed between fixed and adaptive directional microphone conditions. Analysis of individual outcomes shows a wide range of both absolute speech recognition scores and directional benefit across treatment conditions.

The effects of an adaptive directional BEAM microphone on the mismatch negativity responses of cochlear implant users in noise

To investigate the effects of noise on mismatch negativity (MMN) responses and the possible benefits of an adaptive directional BEAM microphone in noise during MMN recordings, and to compare the cochlear implant-evoked potential results with normal hearing subjects. Materials and methods: /da/ and /di/ speech stimuli were used to elicit MMN responses in 11 Freedom cochlear implant users and in 11 normal hearing subjects. Speech noise was delivered at 80 dB sound pressure level (-10 dB signal-to-noise ratio). All subjects were tested in quiet and noisy conditions. To compare the microphone effects, MMN responses for the cochlear implant group were recorded with an omnidirectional and adaptive directional BEAM microphone mode in noise. Results: The MMN responses of the cochlear implantees and the normal hearing group were remarkably similar in terms of latency, amplitude, and morphology in both quiet and noisy conditions. MMN peak latencies were significantly prolonged in the noisy conditions compared to the quiet conditions for both groups. There was a significant decrease in MMN latencies when using an adaptive directional microphone in noise. Conclusion: MMN could be a useful tool to evaluate postoperative cortical auditory performance. BEAM technology provides an ease of discrimination similar to quiet settings for cochlear implant recipients in noisy environments (BEAM and Freedom are trademarks of Cochlear Limited).