Sequential critical periods for the development of binaural integration in the infant mouse auditory cortex

Early binaural experience can recalibrate central auditory circuits that support spatial hearing. However, it is not known how binaural integration matures shortly after hearing onset or whether various developmental stages are differentially impacted by disruptions of normal binaural experience. Here we induce a brief, reversible unilateral conductive hearing loss (CHL) at several experimentally determined milestones in mouse primary auditory cortex (A1) development and characterize its effects approximately one week after normal hearing is restored. We find that experience shapes A1 binaural selectivity during two early critical periods. CHL before P16 disrupts the normal co-registration of interaural frequency tuning, whereas CHL on P16, but not before or after, disrupts interaural level difference (ILD) sensitivity contained in long-latency spikes. These data highlight an evolving plasticity in the developing auditory cortex that may relate to the etiology of amblyaudia, a binaural hearing impairment associated with bouts of otitis media during human infancy

The effects of asymmetric directional microphone fittings on acceptance of background noise

The present study investigated the effects of asymmetric directional microphone fittings (i.e., an omnidirectional microphone on one ear and a directional microphone on the other) on speech understanding in noise and acceptance of background noise in 15 full-time hearing aid users. Subjects were fitted binaurally with four directional microphone conditions (i.e., binaural omnidirectional, asymmetric right directional, asymmetric left directional and binaural directional microphones) using Siemens Intuis directional behind-the-ear hearing aids and comply earmolds. The results revealed that speech understanding in noise improved when using asymmetric directional microphones compared to binaural omnidirectional microphone fittings and were not significantly hindered compared to binaural directional microphone fittings. The results also revealed that listeners who wore asymmetric directional microphones were more likely to accept background noise (i.e., accept hearing aids) than listeners fitted with binaural omnidirectional microphones. Lastly, the results revealed that the ANLs were better for the binaural directional microphones when compared to the asymmetric directional microphones, maximizing listeners\u27 willingness to wear hearing aids in the presence of noise

A Link Loss Model for the On-body Propagation Channel for Binaural Hearing Aids

Binaural hearing aids communicate with each other through a wireless link for synchronization. A propagation model is needed to estimate the ear-to-ear link loss for such binaural hearing aids. The link loss is a critical parameter in a link budget to decide the sensitivity of the transceiver. In this paper, we have presented a model for the deterministic component of the ear-to-ear link loss. The model takes into account the dominant paths having most of the power of the creeping wave from the transceiver in one ear to the transceiver in other ear and the effect of the protruding part of the outer ear called pinna. Simulations are done to validate the model using in-the-ear (ITE) placement of antennas at 2.45 GHz on two heterogeneous phantoms of different age-group and body size. The model agrees with the simulations. The ear-to-ear link loss between the antennas for the binaural hearing aids in the homogeneous SAM phantom is compared with a heterogeneous phantom. It is found that the absence of the pinna and the lossless shell in the SAM phantom underestimate the link loss. This is verified by the measurements on a phantom where we have included the pinnas fabricated by 3D-printing

A binaural grouping model for predicting speech intelligibility in multitalker environments

Spatially separating speech maskers from target speech often leads to a large intelligibility improvement. Modeling this phenomenon has long been of interest to binaural-hearing researchers for uncovering brain mechanisms and for improving signal-processing algorithms in hearing-assistive devices. Much of the previous binaural modeling work focused on the unmasking enabled by binaural cues at the periphery, and little quantitative modeling has been directed toward the grouping or source-separation benefits of binaural processing. In this article, we propose a binaural model that focuses on grouping, specifically on the selection of time-frequency units that are dominated by signals from the direction of the target. The proposed model uses Equalization-Cancellation (EC) processing with a binary decision rule to estimate a time-frequency binary mask. EC processing is carried out to cancel the target signal and the energy change between the EC input and output is used as a feature that reflects target dominance in each time-frequency unit. The processing in the proposed model requires little computational resources and is straightforward to implement. In combination with the Coherence-based Speech Intelligibility Index, the model is applied to predict the speech intelligibility data measured by Marrone et al. The predicted speech reception threshold matches the pattern of the measured data well, even though the predicted intelligibility improvements relative to the colocated condition are larger than some of the measured data, which may reflect the lack of internal noise in this initial version of the model.R01 DC000100 - NIDCD NIH HH

Hearing aid controlled by binaural source localizer

An adaptive directional hearing aid system comprising a left hearing aid and a right hearing aid, wherein a binaural acoustic source localizer is located in the left hearing aid or in the right hearing aid or in a separate body- worn device connected wirelessly to the left hearing aid and the right hearing aid, the binaural acoustic source localizer configured to receive input signals from the left hearing aid and the right hearing aid and generate a control signal to control the update of a first adaptive beam former in the left hearing aid and a second adaptive beam former in the second hearing aid is disclosed. The disclosed system improves speech intelligibility and listening comfort for the user in noisy environments

Asymmetric adjustment

A method of adjusting a signal processing parameter for a first hearing aid and a second hearing aid forming parts of a binaural hearing aid system to be worn by a user is provided. The binaural hearing aid system comprises a user specific model representing a desired asymmetry between a first ear and a second ear of the user. The method includes detecting a request for processing a parameter change at the first hearing aid, adjusting the signal processing parameter in the first hearing aid, and adjusting a processing parameter for the second hearing aid based on the request for processing parameter change and the user specific model.</p