From sounds to meaning: the role of attention during auditory scene analysis

from Current Opinion in Otolaryngology and Head and Neck Surgery

Purpose of review: From the cochlea to associative auditory cortex, incoming acoustic data undergo a series of transformations that allow us to build up representations of the various sound sources present in the environment. Here, we examine the role of selective attention in this process, with an emphasis on studies understanding how the human brain solves complex auditory scenes. We also examine the potential usefulness of the scene analysis framework in research and clinical application to hearing problems.

Recent findings: Evidence from behavioral and neuroimaging studies suggests that auditory scene analysis engages attention-independent as well as attention-dependent processes. Selective attention may enhance figure-ground segregation via a sensory gain control mechanism that enhances the processing of task-relevant acoustic data, and a suppression mechanism that attenuates neuronal responses to task-irrelevant stimuli. Moreover, selective attention keeps sound representations active in memory, thereby easing their integration and comparison with stored (schemata) representations of prior sound objects.

Summary: Understanding an auditory scene requires complex interactions between data-driven and higher level schema-driven processes that reflect listeners’ knowledge and experiences with the auditory environment. Such interactions are at the forefront of hearing and determine our perceptual experience.

Gap junctions and connexins in the inner ear: their roles in homeostasis and deafness

from Current Opinion in Otolaryngology and Head and Neck Surgery

Purpose of review: Mutations in GJB2 and GJB6, the genes encoding the gap-junction proteins connexin 26 and connexin 30, are the most common cause of autosomal recessive nonsyndromic deafness in many populations across the world. In this review, we discuss current ideas about the roles of gap junctions in the inner ear and the implications of connexin mutations on auditory function.

Recent findings: In recent years, a complex picture of the roles of gap junctions in cochlear physiology emerged. Rather than being mere conduits for the circulation of potassium ions in the inner ear, gap junctions have been implicated in intercellular signaling among nonsensory cells and may be involved in the maintenance of the endothelial barrier in the stria vascularis. Studies of mutant channels and mouse models for connexin-related deafness have provided valuable insights into some of the mechanisms by which connexin dysfunction causes cochlear degeneration. They have also identified potential therapeutic interventions for specific connexin mutations, such as the restoration of normal connexin 26 protein levels in GJB6-associated deafness.

Summary: Despite recent advances, a better understanding of the complexity of gap-junctional communication in the inner ear and the structure-function relationships of connexin proteins is required for the development of mechanism-based treatments of connexin-associated hearing loss.

Implantable hearing devices

from Current Opinion in Otolaryngology and Head and Neck Surgery

Purpose of review: Implantable hearing devices have been developed to address the shortcomings of traditional hearing aids. Currently, there are two US Food and Drug Administration clinical trials evaluating fully implantable hearing devices.

Recent findings: Implantable hearing devices attempt to improve upon stigma, cosmesis, occlusion effect, and feedback, as well as other factors that prevent patients from using traditional hearing aids. However, there are many challenges inherent in designing an implantable hearing device. Different devices have attempted to overcome these challenges in different ways. We will discuss these differences in design, their individual pros and cons as well as directions of future research.

Summary: Although implantable hearing devices are not currently available they do hold promise for patients not adequately served by conventional hearing aids.

KCNQ4 mutations associated with nonsyndromic progressive sensorineural hearing loss

from Current Opinion in Otolaryngology and Head and Neck Surgery

Purpose of review: This article provides an update on the current progress in identification of KCNQ4 mutations responsible for DFNA2, a subtype of autosomal dominant nonsyndromic progressive hearing loss.

Recent findings: Hearing loss in pateints with DFNA2 usually start at high frequencies in their 20s and 30s, and then progress to more than 60 dB in less than 10 years, with middle and low frequencies often affected as well. To date, eight missense mutations and two deletions of the KCNQ4 gene have been identified in patients with DFNA2 with various clinical phenotypes. In general, missense mutations are associated with younger-onset and all-frequency hearing loss, whereas deletion mutations are underlying later-onset and pure high-frequency hearing loss. The etiology of DFNA2 remains largely unknown at this point, even though the degeneration of cochlear outer hair cells, caused by dysfunction of KCNQ4 channels, might be one of the underlying mechanisms.

Summary: During the last decade, significant progress has been made in identifying KCNQ4 mutations in patients with DFNA2. Elucidation of the pathogenic effect of these mutations will help to gain insights into the molecular mechanisms of hearing and hearing loss, which, in turn, will facilitate informative genetic counseling, early diagnosis, and even treatment of hearing loss.

The tectorial membrane: one slice of a complex cochlear sandwich

from Current Opinion in Otolaryngology and Head and Neck Surgery

Purpose of review: The review is both timely and relevant, as recent findings have shown the tectorial membrane plays a more dynamic role in hearing than hitherto suspected, and that many forms of deafness can result from mutations in tectorial membrane proteins.

Recent findings: Main themes covered are the molecular composition, the structural organization and properties of the tectorial membrane, the role of the tectorial membrane as a second resonator and a structure within which there is significant longitudinal coupling, and how mutations in tectorial membrane proteins cause deafness in mice and men.

Conclusion: Findings from experimental models imply that the tectorial membrane plays multiple, critical roles in hearing. These include coupling elements along the length of the cochlea, supporting a travelling wave and ensuring the gain and timing of cochlear feedback are optimal. The clinical findings suggest stable, moderate-to-severe forms of hereditary hearing loss may be diagnostic of a mutation in TECTA, a gene encoding one of the major, noncollagenous proteins of the tectorial membrane.

Masters degree addresses chronic speech pathologist shortage

from The University of Sydney News

A specialist University of Sydney masters program could help significantly reduce the acute national shortage of speech pathologists, according to Dr Leanne Togher.

Hearing Aid “Grows” With Child

from MedGadget.com

Fitting a hearing instrument for young children with hearing loss is one of the most difficult tasks faced by audiologists. Children born with impaired hearing can only communicate to a very limited degree, and they also have different auditory perception than adults who have suffered gradual loss of hearing. In the latter case, the brain loses its capacity to perceive high frequencies. Children with hearing loss, by contrast, need the full spectrum of sounds in order to “learn how to hear.”

Clinical Outcomes of the Furlow Z-Plasty for Primary Cleft Palate Repair

from the Cleft Palate-Craniofacial Journal

Objective: To review the clinical outcomes following the Furlow Z-plasty for primary cleft palate repair. The primary objective was to determine if the presence of an associated sequence or syndrome (i.e., Pierre Robin sequence), age at palate repair, cleft type, or surgeon experience influenced speech outcomes after a Furlow Z-plasty.

Design: The outcomes of 140 patients who underwent palate repair were analyzed retrospectively. Speech evaluations were performed to score the severity of hypernasality, nasal escape, articulation errors, and velopharyngeal insufficiency.

Results: The mean age at latest evaluation was 4 years 9 months (age range 2 years old to 12 years old and 4 months). Of the 140 patients, 83% had no evidence of hypernasality, 91% had no presence of nasal escape, and 69% had no articulation errors. Overall, 84% of patients had no evidence of velopharyngeal insufficiency. Secondary posterior pharyngeal flap to correct velopharyngeal insufficiency was required in only 2.1% of patients. The formation of an oronasal fistula occurred in only 3.6% of patients. Nonsyndromic patients with Pierre Robin sequence and syndromic patients did just as well as purely nonsyndromic patients in terms of velopharyngeal insufficiency, hypernasality, and nasal escape. Syndromic patients were more likely to make mild-to-moderate articulation errors. In addition, age at palate repair, cleft type, and surgeon experience had no statistically significant effect on speech results.

Conclusions: The Furlow Z-plasty yielded excellent speech results in our patient population with minimal and acceptable rates of fistula formation, velopharyngeal insufficiency, and the need for additional corrective surgery.

Treatment of a Patient With Cleft Lip and Palate Using an Internal Distraction Device

from the Cleft Palate-Craniofacial Journal

A 24-year-old man with a bilateral cleft lip and palate was treated by a multidisciplinary team composed of an orthodontist, plastic surgeon, and prosthodontist with assistance from an engineer. Before treatment, clinical photographs, dental casts, lateral and posteroanterior cephalograms, periapical and panoramic radiographs, and three-dimensional computed tomography (3D CT) images were obtained. He presented with a narrow and retrognathic maxilla with a 23-mm anterior open bite. Following maxillary expansion with rapid palatal expansion, a Le Fort I maxillary osteotomy was performed, and an internal distractor was placed. After a 5-day latency period, internal maxillary distraction was performed at a rate of 1 mm/day achieved by two activations per day. Cephalometric analysis showed a 7-mm maxillary advancement. Mandibular bilateral sagittal split osteotomy was also performed to close the open bite following maxillary distraction and a 3-month stabilization period. Finally, the treatment was completed with prosthetic rehabilitation. The changes in speech production were evaluated using an automatic speech recognition system.

A Study of Speech, Language, Hearing, and Dentition in Children With Cleft Lip Only

from the Cleft Palate-Craniofacial Journal

Objective: To examine the prevalence of speech, language, hearing, and dental problems in children with an initial diagnosis of isolated cleft lip only (CL), for which evidence-based practice can be developed.

Design: Retrospective chart review of 95 patients with cleft lip (age range, 2.8 to 3.7 years; mean, 3.1 years).

Results: Speech and language impairment was documented in 13% and 18% of the patients, respectively. Thirty-three percent of the children presented with middle ear effusion. Thirteen percent had abnormal hearing. With one exception, the type and degree of hearing loss was a mild conductive loss most often attributed to the presence of effusion. Dental and/or occlusal anomalies were documented in 62% of the patients. A supernumerary tooth was the most frequently occurring dental anomaly and crossbite the most frequently occurring occlusal anomaly. Two children had a submucous cleft palate. Resonance was abnormal in 5% of the children.

Conclusion: Children with an initial diagnosis of CL need to be monitored by the interdisciplinary team for speech, language, ear disease, hearing, and dentition beginning in infancy and followed until all management needs are met.