Investigating sound-field reproduction methods as perceived by bilateral hearing aid users and normal-hearing listeners.

A perceptual study was conducted to investigate the perceived accuracy of two sound-field reproduction approaches when experienced by hearing-impaired (HI) and normal-hearing (NH) listeners. The methods under test were traditional signal-independent Ambisonics reproduction and a parametric signal-dependent alternative, which were both rendered at different Ambisonic orders. The experiment was repeated in two different rooms: (1) an anechoic chamber, where the audio was delivered over an array of 44 loudspeakers; (2) an acoustically-treated listening room with a comparable setup, which may be more easily constructed within clinical settings. Ten bilateral hearing aid users, with mild to moderate symmetric hearing loss, wearing their devices, and 15 NH listeners were asked to rate the methods based upon their perceived similarity to simulated reference conditions. In the majority of cases, the results indicate that the parametric reproduction method was rated as being more similar to the reference conditions than the signal-independent alternative. This trend is evident for both groups, although the variation in responses was notably wider for the HI group. Furthermore, generally similar trends were observed between the two listening environments for the parametric method. The signal-independent approach was instead rated as being more similar to the reference in the listening room.

The impact of reverberation on speech intelligibility in cochlear implant recipients.

Listening to speech in an environment with reverberation can be challenging for both the normal and impaired auditory system. However, it has been shown for both normal- and impaired-hearing listeners that it is the late reflections that are responsible for degrading intelligibility, whereas early reflections actually aid intelligibility by increasing the effective signal-to-noise ratio. Contrastingly, studies conducted with cochlear implant (CI) recipients have suggested that CI recipients have almost no tolerance for reverberation and that they are negatively impacted by both early and late reflections. The main objective of the current study is to re-evaluate the influence of reverberation on speech intelligibility in CI recipients using more authentic virtual auditory environments. Unlike previous studies in this area, this study was conducted using a loudspeaker-based auralization system rather than non-individualized binaural room simulations. Speech intelligibility was measured in simulations of a range of actual physical rooms with plausible source-receiver distances, both with and without late reflections. The results show that the effect of reverberation is much smaller than previously suggested, especially with short source-receiver distances. Furthermore, the results suggest that, in contrast to previous literature, early reflections may not actually be detrimental to CI recipients.

Outcome measures based on classification performance fail to predict the intelligibility of binary-masked speech.

To date, the most commonly used outcome measure for assessing ideal binary mask estimation algorithms is based on the difference between the hit rate and the false alarm rate (H-FA). Recently, the error distribution has been shown to substantially affect intelligibility. However, H-FA treats each mask unit independently and does not take into account how errors are distributed. Alternatively, algorithms can be evaluated with the short-time objective intelligibility (STOI) metric using the reconstructed speech. This study investigates the ability of H-FA and STOI to predict intelligibility for binary-masked speech using masks with different error distributions. The results demonstrate the inability of H-FA to predict the behavioral intelligibility and also illustrate the limitations of STOI. Since every estimation algorithm will make errors that are distributed in different ways, performance evaluations should not be made solely on the basis of these metrics.

Cochlear Implantation in Sporadic Intralabyrinthine Schwannomas with Single-Sided Deafness: Implications for Binaural Hearing.

BACKGROUND AND OBJECTIVE: Intralabyrinthine schwannomas (ILSs) may have detrimental effects on ipsilateral hearing, commonly leading to single-sided deafness (SSD). Cochlear implantation in patients with ILSs is an option to partly restore ipsilateral hearing; however, the available literature fails to account for the binaural hearing benefits of a cochlear implant (CI) for ILSs. METHODS: We prospectively evaluated SSD patients with sporadic ILS undergoing cochlear implantation with simultaneous tumor resection (n = 10) or with tumor observation (n = 1). Patients completed the Speech, Spatial and Qualities Questionnaire (SSQ12) and the Nijmegen Cochlear Implant Questionnaire (NCIQ) pre- and postoperatively, as well as the Bern Benefit in Single-Sided Deafness (BBSSD) questionnaire postoperatively. Patients were also tested postoperatively with and without their CI to measure the effect on localization ability and binaural summation, squelch, and head shadow. RESULTS: Evaluation was completed for nine and six patients (subjective and objective data, respectively). The CI significantly improved the speech reception threshold (SRT) in the head shadow condition where the target signal was presented to the CI side and the noise to the front (SCIN0). On the other hand, the SRTs in the colocated condition (S0N0) and the condition where the target signal was presented to the front and the noise to the CI side (S0NCI) were unaffected by the CI. The mean localization error decreased significantly from 102° to 61° (p = 0.0031) with the addition of a CI. The scores from SSQ12 demonstrated nonsignificant changes. For NCIQ, the self-esteem and the social interaction domains increased significantly but insignificantly for the remaining domains. The BBSSD responses ranged from +0.5 to +3.5 points. CONCLUSION: After implantation, patients achieved significantly better scores across some of the patient-reported and objective parameters. In addition to reporting on a number of ILS cases where implantation was performed, the study is the first of its kind to document patient-reported and objective binaural hearing improvement after cochlear implantation in patients with ILS and, thereby, lends support to the active management of ILS.

Baseline pupil size encodes task-related information and modulates the task-evoked response in a speech-in-noise task.

Pupillometry data are commonly reported relative to a baseline value recorded in a controlled pre-task condition. In this study, the influence of the experimental design and the preparatory processing related to task difficulty on the baseline pupil size was investigated during a speech intelligibility in noise paradigm. Furthermore, the relationship between the baseline pupil size and the temporal dynamics of the pupil response was assessed. The analysis revealed strong effects of block presentation order, within-block sentence order and task difficulty on the baseline values. An interaction between signal-to-noise ratio and block order was found, indicating that baseline values reflect listener expectations arising from the order in which the different blocks were presented. Furthermore, the baseline pupil size was found to affect the slope, delay and curvature of the pupillary response as well as the peak pupil dilation. This suggests that baseline correction might be sufficient when reporting pupillometry results in terms of mean pupil dilation only, but not when a more complex characterization of the temporal dynamics of the response is considered. By clarifying which factors affect baseline pupil size and how baseline values interact with the task-evoked response, the results from the present study can contribute to a better interpretation of the pupillary response as a marker of cognitive processing.

Nordic results of cochlear implantation in adults: speech perception and patient reported outcomes.

BACKGROUND: Although cochlear implantation (CI) is widely performed in postlingually hearing-impaired adults in the Nordic countries, the literature on hearing outcomes remains scarce. Aims/objectives: To evaluate and correlate hearing outcomes after implantation. METHODS: Prospective evaluation of 40 adult first-implantation recipients pre- and post-implantation with Dantale, the Danish Hearing in Noise Test (HINT), the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the Speech, Spatial and Qualities of Hearing Scale (SSQ12). RESULTS: Dantalemean increased from 50% (95% CI [41.7,58.4])) to 73% (95% CI [66.6,80.1]) and 19% (95% CI [13.3,25.1]) to 40%(95% CI [32.1,46.7]) (quiet/noise). HINTwords increased from 71% (95% CI [58.8,83.8]) to 83% (95% CI [69.8,95.4]) and 59% (95% CI [46.2,70.6]) to 73% (95% CI [63.3,82.8]) (quiet/noise). NCIQmean changed from 277 (95% CI [252.4,301.6]) to 396 (95% CI [366.7,424.7]) and SSQ12mean from 27 (95% CI [21.3,31.8]) to 48 (95% CI [39.4,55.6]). Correlations coefficients were r s = 0.39-0.74 (p < .01) between Dantale/HINT, rs = 0.78 (p < .0001) between NCIQ/SSQ12, r s = 0.41-0.59 (p < .01) between NCIQ/SSQ12 and Dantale and r s = 0.24-0.41 (ns) between NCIQ/SSQ12 and HINT. CONCLUSION: The study documents a high auditory performance and patient-perceived improvement after implantation and advocate broader awareness of implantation as treatment option in the growing population of severe-to-profound hearing-impaired adults. Correlations between hearing measures may influence future evaluation practices.