Sound Localization Research Articles

Hybrid Cochlear Implant Outcomes and Improving Outcomes With Electric-Acoustic Stimulation.

Electric-acoustic stimulation (EAS) provides cochlear implant (CI) recipients with preserved low-frequency acoustic hearing in the implanted ear affording auditory cues not reliably transmitted by the CI including fundamental frequency, temporal fine structure, and interaural time differences (ITDs). A prospective US multicenter clinical trial was conducted examining the safety and effectiveness of a hybrid CI for delivering EAS. Fifty-two adults (mean age 59.9 yr) were enrolled in the study and followed up to 5 years postactivation. Testing included unaided and aided audiometric thresholds, speech perception (Consonant-Nucleus-Consonant [CNC] words in quiet and AzBio sentences +5 dB SNR), and patient-reported outcomes (Speech, Spatial, and Qualities of Hearing Scale). Functionally aidable hearing, defined as low-frequency pure-tone average (125-500 Hz) <80 dB HL, was maintained for 77% of patients through 1 year, with 66.7% maintaining through 5 years. Speech perception was significantly improved at all postoperative timepoints compared with preoperative performance with hearing aid(s), and patient-reported outcomes indicated significantly improved subjective speech understanding, spatial hearing, and sound quality. Participants with preserved acoustic hearing using EAS reported significantly higher subjective spatial hearing and sound quality than participants with electric-only hearing in the implanted ear. Patients with high-frequency hearing loss demonstrate significant long-term benefit with a hybrid CI including high rates of functional hearing preservation, significantly improved speech perception, and subjective patient-reported outcomes. EAS with binaural acoustic hearing affords benefit for subjective spatial hearing and sound quality beyond CI listening configurations using monaural acoustic hearing.

CRATI: Contrastive representation-based multimodal sound event localization and detection

CRATI: Contrastive representation-based multimodal sound event localization and detection

Spectral splitting of speech signal using time varying recursive filters for binaural hearing aids

&lt;p&gt;Speech perception in noisy environments is reduced in human with sensorineural hearing loss (SNHL) due to masking. Moderate SNHL cannot be cured medically hence masking effects should be reduced to enhance speech perception. To reduce masking, processing delay and hardware complexity the present paper is proposed a scheme to partition the voice signal into two signals which are complementary to each other by using the filter-bank summation method (FBSM) with a set of time-varying recursive band pass filters. Performance of the filter is evaluated with following measures: perceptual evaluation of speech quality (PESQ), mean opinion score (MOS) for speech quality and modified rhyme test (MRT) for speech intelligibility. The test signals used for the evaluation of quality are a syllable and a word and for the evaluation of intelligibility 300 monosyllabic words are used. The results demonstrated an increase in the quality and intelligibility of processed speech in a noisy environment. As a result, there is an enhancement in perception of processed speech in a noisy environment.&lt;/p&gt;

A review on deep learning methods for heart sound signal analysis

IntroductionApplication of Deep Learning (DL) methods is being increasingly appreciated by researchers from the biomedical engineering domain in which heart sound analysis is an important topic of study. Diversity in methodology, results, and complexity causes uncertainties in obtaining a realistic picture of the methodological performance from the reported methods.MethodsThis survey paper provides the results of a broad retrospective study on the recent advances in heart sound analysis using DL methods. Representation of the results is performed according to both methodological and applicative taxonomies. The study method covers a wide span of related keywords using well-known search engines. Implementation of the observed methods along with the related results is pervasively represented and compared.Results and discussionIt is observed that convolutional neural networks and recurrent neural networks are the most commonly used ones for discriminating abnormal heart sounds and localization of heart sounds with 67.97% and 33.33% of the related papers, respectively. The convolutional neural network and the autoencoder network show a perfect accuracy of 100% in the case studies on the classification of abnormal from normal heart sounds. Nevertheless, this superiority against other methods with lower accuracy is not conclusive due to the inconsistency in evaluation.

Enhancing sound source localization and music teaching through integrated computational resource allocation

In contemporary educational and computational settings, the incorporation of cutting-edge technologies like sound source localization and personalized music teaching helps in offering an effective resource allocation strategies. Previous systems for sound localization and music teaching frequently lacked real-time flexibility and effective resource use, reducing their efficiency in dynamic learning settings and tasks involving computation. To overcome these shortcomings, the SoundLocMusicTeachRA (SLMTRA) algorithm is presented, a single, integrated platform made to maximize sound localization accuracy, improve music teaching efficiency, and enhance computational resource oversight. However, the existing study did not highlight the importance of computation resource allocation but this proposed algorithm will address it. SLMTRA uses a new Bagging ensemble approach incorporating Random Forest (RF), Decision Trees (DT), Naive Bayes (NB), Support Vector Machine (SVM), and K-Nearest Neighbor (KNN), with hyperparameter tuning to enhance the effectiveness of the approach. These classifiers are trained utilizing sound localization datasets from recordings made with microphones, music teaching feedback datasets from data on student performance, and resource allocation datasets from metrics for computer utilization. Experimental findings indicate SLMTRA’s high accuracy in sound source localization, improved music teaching feedback capacities, as well as effective resource allocation tactics, guaranteeing the best performance of the system. The implementation of SLMTRA represents a noteworthy development in combining sound localization, music teaching, and resource allocation within a unified computational framework, offering a more flexible and effective system compared to previous methodologies.

Happy new ears: rapid adaptation to novel spectral cues in vertical sound localization.

Happy new ears: rapid adaptation to novel spectral cues in vertical sound localization.

Combined Effect of Noise Reduction, FBS-Based Spectral Splitting, and Dynamic Range Compression of Speech Signal on Source Localization in Binaural Hearing Aids

Localizing sound sources in three spatial dimensions (azimuth, elevation, and distance) is critical for human hearing comfort. It relies on two binaural cues: interaural time difference (ITD) and interaural level difference (ILD). Cochlear or auditory nerve injury can result in sensorineural hearing loss (SNHL). Hearing aids enable people with sensorineural hearing loss to converse more effectively and hear better. However, there is an apprehension that the binaural hearing aids may degrade the localization cues, thus affecting the source localization. In response to this concern, the current study investigates how the binaural hearing aid algorithm affects source localization by adopting a cascaded structure of noise reduction technique (wiener filter) followed by filter bank summation (FBS) based spectral splitting and dynamic range compression for binaural dichotic presentation. Listening tests for seven different azimuth angles (-90⁰, -60⁰, -30⁰, 0⁰, 30⁰, 60⁰, and - 90⁰) were conducted on six listeners with normal hearing under different signal-to-noise ratio (SNR) conditions as well as on six subjects with mild bilateral sensorineural hearing impairment. Test stimuli included background glass-breaking sound and broadband noise for participants with normal hearing. In an experiment with hearing-impaired subjects, the glass-breaking sound served as one of the test stimuli. The result showed that these binaural hearing aid algorithms had no adverse effects on localization ability.

Head rotations follow those of a truncated Fick gimbal during an auditory guided visual search task.

Recent interest in dynamic sound localisation models has created a need to better understand the head movements made by humans. Previous studies have shown that static head positions and small oscillations of the head obey Donders' law: for each facing direction there is one unique three-dimensional orientation. It is unclear whether this same constraint applies to audiovisual localisation, where head movement is unrestricted and subjects may rotate their heads depending on the available auditory information. In an auditory guided visual search task, human subjects were instructed to localise an audiovisual target within a field of visual distractors in the frontal hemisphere. During this task, head and torso movements were monitored using a motion capture system. Head rotations were found to follow Donders' law during search tasks. Individual differences were present in the amount of roll that subjects deployed, though there was no statistically significant improvement in model performance when including these individual differences in a gimbal model. The roll component of head rotation could therefore be predicted with a truncated Fick gimbal, which consists of a pitch axis nested within a yaw axis. This led to a reduction from three to two degrees of freedom when modelling head movement during localisation tasks.

Functional Connectivity Encodes Sound Locations by Lateralization Angles.

The ability to localize sound sources rapidly allows human beings to efficiently understand the surrounding environment. Previous studies have suggested that there is an auditory "where" pathway in the cortex for processing sound locations. The neural activation in regions along this pathway encodes sound locations by opponent hemifield coding, in which each unilateral region is activated by sounds coming from the contralateral hemifield. However, it is still unclear how these regions interact with each other to form a unified representation of the auditory space. In the present study, we investigated whether functional connectivity in the auditory "where" pathway encoded sound locations during passive listening. Participants underwent functional magnetic resonance imaging while passively listening to sounds from five distinct horizontal locations (-90°, -45°, 0°, 45°, 90°). We were able to decode sound locations from the functional connectivity patterns of the "where" pathway. Furthermore, we found that such neural representation of sound locations was primarily based on the coding of sound lateralization angles to the frontal midline. In addition, whole-brain analysis indicated that functional connectivity between occipital regions and the primary auditory cortex also encoded sound locations by lateralization angles. Overall, our results reveal a lateralization-angle-based representation of sound locations encoded by functional connectivity patterns, which could add on the activation-based opponent hemifield coding to provide a more precise representation of the auditory space.

Audiological and Subjective Benefits in a Child with Microtia and Atresia After Sequential Bilateral Implantation with Active Bone Conduction Devices: A Case Study

Background: With bilateral hearing loss, the main problems for the patient are speech understanding in noise and, especially in asymmetrical hearing loss, an inability to correctly localize sound sources. There are multiple methods of treatment and rehabilitation for people with conductive hearing loss, and one of them is to use an active bone conduction implant. This case study is designed to evaluate the auditory benefits and sound localization accuracy with active bilateral bone conduction implants—in comparison to unilateral ones—in a patient with congenital bilateral conductive hearing loss caused by a congenital malformation. We assess subjective and audiological benefits (functional, directional hearing, speech comprehension in quiet and noise). Case report: This study describes the results in a 15-year-old patient with bilateral congenital malformation of the outer ears and associated conductive hearing loss who was treated with two Bonebridge active bone conduction implants. Speech recognition ability, hearing thresholds, and sound localization were tested under three conditions: unaided, unilateral on the right-side, and bilateral on both sides. The patient filled in an Abbreviated Profile of Hearing Aid Benefit questionnaire (APHAB) to evaluate limitations in daily life caused by hearing impairment. The results show an improvement in free-field hearing thresholds and the ability to discriminate speech, both in quiet and in noise after implantation. Subjectively, the patient had significantly fewer problems with two implants than with one (or with no implant) in terms of hearing in everyday situations. Conclusions: Unilateral use of the Bonebridge device in a patient with congenital bilateral conductive hearing loss did not provide full benefits. However, bilateral implantation improved speech understanding in noise and sound localization.

Equipment Sounds’ Event Localization and Detection Using Synthetic Multi-Channel Audio Signal to Support Collision Hazard Prevention

Construction workplaces often face unforeseen collision hazards due to a decline in auditory situational awareness among on-foot workers, leading to severe injuries and fatalities. Previous studies that used auditory signals to prevent collision hazards focused on employing a classical beamforming approach to determine equipment sounds’ Direction of Arrival (DOA). No existing frameworks implement a neural network-based approach for both equipment sound classification and localization. This paper presents an innovative framework for sound classification and localization using multichannel sound datasets artificially synthesized in a virtual three-dimensional space. The simulation synthesized 10,000 multi-channel datasets using just fourteen single sound source audiotapes. This training includes a two-staged convolutional recurrent neural network (CRNN), where the first stage learns multi-label sound event classes followed by the second stage to estimate their DOA. The proposed framework achieves a low average DOA error of 30 degrees and a high F-score of 0.98, demonstrating accurate localization and classification of equipment near workers’ positions on the site.

First photon-counting detector computed tomography in the living crocodile: a 3D-Imaging study with special reference to amphibious hearing.

Crocodiles are semi-aquatic animals well adapted to hear both on land and under water. Currently, there is limited information on how their amphibious hearing is accomplished. Here, we describe, for the first time, the ear anatomy in the living crocodile using photon-counting detector computed tomography (PCD-CT) and 3D rendering. We speculate on how crocodiles, despite their closed ear canals, can use tympanic hearing in water that also provides directional hearing. A Cuban crocodile (Crocodylus rhombifer) underwent photon-counting detector computed tomography (PCD-CT), under anesthesia and spontaneous respiration. In addition two seven-month-old C. rhombifer and a juvenile Morelet´s crocodile (Crocodylus moreletii) underwent micro-computed tomography (µCT) and endoscopy. One adult Cuviérs dwarf caiman (Paleosuchus palpebrosus) was micro-dissected and video-recorded. Aeration, earflap, and middle ear morphology were evaluated and compared after 3D modeling. PCD-CT and µCT with 3D rendering and segmentation demonstrated the anatomy of the external and middle ears with high resolution in both living and expired crocodiles. Based on the findings and comparative examinations, we suggest that the superior earflap, by modulating the meatal recess together with local bone conduction, may implement tympanic hearing in submerged crocodiles, including directional hearing.

Distinct Neuron Types Contribute to Hybrid Auditory Spatial Coding.

Neural decoding is a tool for understanding how activities from a population of neurons inside the brain relate to the outside world and for engineering applications such as brain-machine interfaces. However, neural decoding studies mainly focused on different decoding algorithms rather than different neuron types which could use different coding strategies. In this study, we used two-photon calcium imaging to assess three auditory spatial decoders (space map, opponent channel, and population pattern) in excitatory and inhibitory neurons in the dorsal inferior colliculus of male and female mice. Our findings revealed a clustering of excitatory neurons that prefer similar interaural level difference (ILD), the primary spatial cues in mice, while inhibitory neurons showed random local ILD organization. We found that inhibitory neurons displayed lower decoding variability under the opponent channel decoder, while excitatory neurons achieved higher decoding accuracy under the space map and population pattern decoders. Further analysis revealed that the inhibitory neurons' preference for ILD off the midline and the excitatory neurons' heterogeneous ILD tuning account for their decoding differences. Additionally, we discovered a sharper ILD tuning in the inhibitory neurons. Our computational model, linking this to increased presynaptic inhibitory inputs, was corroborated using monaural and binaural stimuli. Overall, this study provides experimental and computational insight into how excitatory and inhibitory neurons uniquely contribute to the coding of sound locations.

Combined Keyword Spotting and Localization Network Based on Multi-Task Learning

The advent of voice assistance technology and its integration into smart devices has facilitated many useful services, such as texting and application execution. However, most assistive technologies lack the capability to enable the system to act as a human who can localize the speaker and selectively spot meaningful keywords. Because keyword spotting (KWS) and sound source localization (SSL) are essential and must operate in real time, the efficiency of a neural network model is crucial for memory and computation. In this paper, a single neural network model for KWS and SSL is proposed to overcome the limitations of sequential KWS and SSL, which require more memory and inference time. The proposed model uses multi-task learning to utilize the limited resources of the device efficiently. A shared encoder is used as the initial layer to extract common features from the multichannel audio data. Subsequently, the task-specific parallel layers utilize these features for KWS and SSL. The proposed model was evaluated on a synthetic dataset with multiple speakers, and a 7-module shared encoder structure was identified as optimal in terms of accuracy, direction of arrival (DOA) accuracy, DOA error, and latency. It achieved a KWS accuracy of 94.51%, DOA error of 12.397°, and DOA accuracy of 89.86%. Consequently, the proposed model requires significantly less memory owing to the shared network architecture, which enhances the inference time without compromising KWS accuracy, DOA error, and DOA accuracy.

Improving speech intelligibility in noise and spatial perception: the critical role of hearing aid microphone position.

Hearing aid (HA) manufacturers have introduced behind-the-ear (BTE) models where the microphone is positioned in the ear canal, which could impact auditory performance by distorting the pinna's acoustic cues. This study aimed to compare two different BTE HAs with varying microphone positions: the receiver in the ear (RITE) and the transducer in the ear (TIE). The study involved 10 participants who had never used HAs before. They used both RITE and TIE HAs bilaterally for 3 weeks. Auditory performance was assessed through free field hearing assessments (hearing thresholds, speech recognition threshold, and speech discrimination score), the Turkish Matrix Sentence Test (TURMatrix), a sound localization test, and the Satisfaction with Amplification in Daily Living (SADL) questionnaire. There was no significant difference between TIE and RITE in the free field hearing assessments. However, TIE outperformed RITE in non-adaptive TURMatrix scores in quiet, adaptive TURMatrix scores in noise, and sound localization accuracy at various angles. SADL sub-scores (Positive Effect, Service and Cost, and Personal Image) and overall satisfaction scores were significantly better for TIE. The microphone position in HAs can influence auditory performance. This study demonstrated that TIE provided better speech intelligibility, localization accuracy, and user satisfaction compared to RITE.

Effect of Bio-Inspired Cutout Shapes at the Leading Edge of Propellers on Noise and Flight Efficiency

In recent years, the application of bio-inspired structures has garnered attention for enhancing the performance of fluid machinery. In this study, we experimentally investigated the effects of introducing a bio-inspired cutout structure to the propellers of drones, aiming to improve thrust efficiency and reduce noise levels. Our results demonstrated reductions in noise levels compared to conventional propellers. Parametric studies revealed that the roundness of the structure significantly influenced both flight efficiency and noise levels, suggesting its importance for replicating the inherent fluid characteristics found in nature. Additionally, optimal parameters for noise reduction, such as the length of the cutout, angle of incision relative to the flow direction, and the distance between the gap were identified. Although no improvements in flight efficiency were observed, most of the models investigated exhibited only around a 5% reduction in efficiency compared to the standard propellers, suggesting practical applicability for scenarios such as nighttime drone operations in urban areas. The noteworthy reduction in sound pressure levels in the mid- to high-frequency range achieved by the bio-inspired propellers in this study holds the potential to address the issue of drone noise pollution and encourage drone operations in urban areas. Moreover, the confirmed decrease in sound pressure at specific frequencies and the suggested controllability hint at the possibility of enhancing sound source localization performance using drones.

Clinical Outcomes for Adult Single-Sided Deafness Cochlear Implantees Exceeding the 5% Candidacy Criterion

Objectives: While single-sided deafness cochlear implants (SSD-CIs) have now received regulatory approval in the United States, candidate-ear candidacy criteria (no better than 5% word-recognition score) are stricter than for traditional CI candidates (50 to 60% speech recognition, best-aided condition). SSD implantation in our center began before regulatory approval, using a criterion derived from traditional candidacy: 50% consonant-nucleus-consonant (CNC) word-identification score in the candidate ear. A retrospective analysis investigated whether SSD patients exceeding the 5% CNC criterion nevertheless benefitted from a CI as assessed by spatial-hearing tests (speech understanding in noise [SIN] and localization) and by a patient-reported outcome measure quality-of-life instrument validated for patients with CIs. Design: A retrospective chart review assessed the clinical experience of a single CI center. Subjects consisted of 27 adult CI recipients with SSD (N = 21) or asymmetric hearing loss (AHL; N = 6) implanted since September 2019 with at least 3 months of postoperative follow-up. Patients with revision surgery or simultaneous labyrinthectomy and CI surgery were excluded from the sample. Subjects were divided into 2 groups based on preoperative CNC scores measured under best-aided conditions with a behind-the-ear hearing aid in the sound field at 0.9 m from a front loudspeaker, and the better ear masked using an insert earphone with 45 dB HL speech-weighted noise. The “MEETS” group had preoperative CNC word scores &lt;5%; the “EXCEEDS” group had scores &gt;5%. The clinical protocol also included intelligibility tests using AzBio sentences in the same test conditions as CNC; binaural spatial testing (broadband-noise sound localization, and matrix-sentence speech-reception thresholds in spatially separated noise) using a custom-built 7-speaker array; and the CI Quality of Life (CIQOL) instrument. To evaluate CI benefit, preoperative unaided performance was compared with postoperative binaural (acoustic ear + CI ear) performance at a clinic visit closest to 6 months postsurgery. Results: Of 27 SSD-CI recipients, 11 subjects exceeded the 5% preoperative CNC candidacy criterion. Both the MEETS and EXCEEDS groups improved significantly on all 5 primary study outcome measures (CI-alone CNC and AzBio, binaural SIN and sound localization, and CIQOL). The only statistically significant differences observed between the MEETS and EXCEEDS groups were that preoperative CNC and AzBio scores were significantly higher for the EXCEEDS group, as expected given that the groups were defined based on preoperative speech-perception scores in quiet. There were no statistically significant differences between the MEETS and EXCEEDS groups in postoperative scores in any test or in the magnitude of the improvement from preoperative to postoperative assessment. Conclusions: SSD- and AHL-CI recipients exceeding the 5% CNC preoperative candidacy criterion significantly improved in CI-alone speech perception, spatial hearing, and subjectively reported CIQOL outcomes and the observed benefits were indistinguishable from SSD- and AHL-CI recipients who met the 5% criterion. A less-restrictive SSD-CI and AHL-CI candidacy criterion should be considered, and larger-scale clinical trials to evaluate CI efficacy using a less-stringent candidate-ear criterion are warranted.

State-of-the-Art on the Impact of Bimodal Acoustic Stimulation on Speech Perception in Noise in Adults: A Systematic Review.

Bimodal stimulation (BS), which combines the use of a cochlear implant (CI) in one ear and a hearing aid (HA) in the opposite ear, is an established strategy to treat hearing loss by exploiting the unique capabilities of each device. CIs stimulate the auditory nerve by bypassing damaged hair cells, while HAs amplify sounds by requiring a functional hearing residual. The aim of this systematic review is to investigate the advantages and disadvantages of BS such as speech perception in noise. We examined clinical studies published from October 2020 to July 2024, following the PRISMA guidelines, focusing on the advantages and disadvantages of BS on speech perception in noise in adulthood. BS in adult patients significantly improves speech perception in quiet and noisy environments, especially for those with increased residual hearing. Unilateral CIs and BS perform similarly in quiet conditions, but BS significantly improves speech discrimination in noisy environments if loudness between the two devices is appropriately balanced. Directional microphones and programming software are new technologies that succeed in reducing environmental noise and improving verbal perception outcomes, although their features in the literature are controversial. In addition, the individuals using BS may face temporal mismatches mainly due to differing device latencies, affecting sound localization. Compensating for these mismatches can enhance localization accuracy. However, modulated noise remains a significant obstacle to verbal perception in noise. Valuable assessment tools such as music tests provide further information on hearing performance and quality of life. More research is needed to define certain selection criteria.

Study on Depth Estimation and Characteristic Analysis of Underwater Source Based on Deep-Sea Broadband Signal Modeling

Studies on estimating the underwater sound source localization using acoustic signal characteristics have mainly been conducted in shallow waters. Recently, technologies for stably and efficiently estimating the underwater sound sources localization using the underwater sound propagation characteristics of the Reliable Acoustic Path(RAP) in deep water areas are being studied. Underwater surveillance technology in deep sea areas is known to have the advantage of having low detection performance variability due to time-varying underwater environments and having a small shadow zone, making it easy to stably detect underwater sound sources and estimate location even from relatively long distance. In this study, we analyzed the sound propagation characteristics based on the actual marine environment in the deep sea of the Korean Peninsula and conducted a study to analyze the estimation performance of sound source depth using the broadband interference pattern of direct wave and sea surface reflected waves radiating from underwater sound sources.

Cochlear implantation for children with single-sided deafness: parents’ perspectives

ABSTRACT Historically, cochlear implantation is reserved for those with bilateral severe to profound hearing loss. However, indications have expanded to include Single-Sided Deafness (SSD) because of the known benefits of binaural hearing and the limitations of unilateral hearing, especially for children developing linguistic and cognitive skills. This study aimed to provide a qualitative perspective of lived experiences of children with SSD who use a cochlear implant (CI), as perceived and reported by their parents. An online questionnaire was developed and distributed to evaluate outcomes of cochlear implantation in children with SSD residing in New Zealand and the United States. Qualitative content analysis of open-ended questions identified themes, including: (1) motivating factors; (2) benefits of amplification; (3) challenges associated with the CI journey; and (4) advice to parents. Parents described benefits and challenges as a result of cochlear implantation, such as access to sound and academic and psychosocial development, as well as subjective improvements in spatial hearing, reduced listening fatigue, enhanced academic performance, and changes in quality of life. The difference that bilateral hearing makes to a child’s development is difficult to precisely define but parental insights offer valuable perspective to healthcare providers when considering what some consider an elective procedure.