Acoustical and Perceptual Comparison of Noise Reduction and Compression in Hearing Aids.

Purpose: Noise reduction and dynamic-range compression are generally applied together in hearing aids but may have opposite effects on amplification. This study evaluated the acoustical and perceptual effects of separate and combined processing of noise reduction and compression.

Design: Recordings of the output of 4 hearing aids for speech in babble noise at +4 dB signal-to-noise ratio were used in 3 experiments: (a) acoustical measurements to determine the influence of processing on speech and noise levels; (b) perceptual measurements to determine the detectability of processing differences for 16 listeners with hearing impairment; and (c) perceptual measurements to determine the effect of processing on speech intelligibility, noise annoyance, speech naturalness, and overall preference.

Effects of noise reduction on speech intelligibility, perceived listening effort, and personal preference in hearing-impaired listeners.

This study evaluates the perceptual effects of single-microphone noise reduction in hearing aids. Twenty subjects with moderate sensorineural hearing loss listened to speech in babble noise processed via noise reduction from three different linearly fitted hearing aids. Subjects performed (a) speech-intelligibility tests, (b) listening-effort ratings, and (c) paired-comparison ratings on noise annoyance, speech naturalness, and overall preference.

Detection threshold for sound distortion resulting from noise reduction in normal-hearing and hearing-impaired listeners.

Hearing-aid noise reduction should reduce background noise, but not disturb the target speech. This objective is difficult because noise reduction suffers from a trade-off between the amount of noise removed and signal distortion. It is unknown if this important trade-off differs between normal-hearing (NH) and hearing-impaired (HI) listeners.

Perceptual effects of noise reduction by time-frequency masking of noisy speech.

Time-frequency masking is a method for noise reduction that is based on the time-frequency representation of a speech in noise signal. Depending on the estimated signal-to-noise ratio (SNR), each time-frequency unit is either attenuated or not. A special type of a time-frequency mask is the ideal binary mask (IBM), which has access to the real SNR (ideal).

Perceptual effects of noise reduction with respect to personal preference, speech intelligibility, and listening effort.

Objectives: Most modern hearing aids use noise reduction to increase listening comfort in noisy environments. However, it is unclear whether perceptual effects (e.g.

Status of genomic imprinting in epigenetically distinct pluripotent stem cells.

Mouse epiblast stem cells (EpiSCs) derived from postimplantation embryos are developmentally and functionally different from embryonic stem cells (ESCs) generated from blastocysts. EpiSCs require Activin A and FGF2 signaling for self-renewal, similar to human ESCs (hESCs), while mouse ESCs require LIF and BMP4. Unlike ESCs, EpiSCs have undergone X-inactivation, similar to the tendency of hESCs.

A method to remove differences in frequency response between commercial hearing aids to allow direct comparison of the sound quality of hearing-aid features.

Goal: We want to remove differences in frequency response between different commercial hearing aids so that we can compare the sound quality of signal processing features from different hearing-aid in a future paired-comparison set-up. More specifically, we want to control for the confounding effects of the linear hearing aid response when evaluating nonlinear processing. This article presents a control procedure and evaluates its effectiveness.

Nuclear transfer-derived epiblast stem cells are transcriptionally and epigenetically distinguishable from their fertilized-derived counterparts.

Mouse embryonic pluripotent stem cells can be obtained from the inner cell mass at the blastocyst stage (embryonic stem cells, ESCs) or from the late epiblast of postimplantation embryos (epiblast stem cells, EpiSCs). During normal development, the transition between these two stages is marked by major epigenetic and transcriptional changes including DNA de novo methylation. These modifications represent an epigenetic mark conserved in ESCs and EpiSCs.

Derivation of pluripotent epiblast stem cells from mammalian embryos.

Although the first mouse embryonic stem (ES) cell lines were derived 25 years ago using feeder-layer-based blastocyst cultures, subsequent efforts to extend the approach to other mammals, including both laboratory and domestic species, have been relatively unsuccessful. The most notable exceptions were the derivation of non-human primate ES cell lines followed shortly thereafter by their derivation of human ES cells. Despite the apparent common origin and the similar pluripotency of mouse and human embryonic stem cells, recent studies have revealed that they use different signalling pathways to maintain their pluripotent status.

[Allogenic islet transplantation on the rat liver after allogenic nonparenchymal cells injection in the thymus].

Background: [corrected] The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control

Aim: We studied allogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and nonparenchymal cell group (n = 8) respectively with injection of Hanks solution and nonparenchymal cells in the thymus before islet transplantation.

An overview on the development of a bio-artificial pancreas as a treatment of insulin-dependent diabetes mellitus.

This paper presents the concept and most of the research undertaken all over the world for the development of a bio-artificial pancreas (BAP) device over the last 30 years. The devices studied, meant to mimic the insulin secretion of the natural organ, were diverse and have been reviewed. Allogeneic or xenogeneic cells or cell clusters have been separated from the host's immune system by synthetic biocompatible semipermeable membranes to prevent the need, of the host, for immune-suppressing regimens.

[Alogenic islet transplantation on the rat liver after alogenic dendritic cells injection in the thymus].

Background: The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control.

Aim: We studied alogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient.

Evidence of macrophage receptors capable of direct recognition of xenogeneic epitopes without opsonization.

Background: We have previously demonstrated that porcine livers perfused with human blood remove most of the erythrocytes from three units of human blood over the course of a 72-h extracorporeal perfusion. Red blood cell loss did not appear to involve classical complement pathway-mediated hemolysis, but instead resulted from porcine Kupffer cell phagocytosis.

Methods: We developed a method incorporating collagenase digestion and metrizamide separation to isolate and maintain porcine Kupffer cells in primary culture.

[Isogenic islet transplantation on the rat liver (method for isolation and purification of the Langerhans islets)].

The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control. We have studied isogenic islet transplantation on the rat (WAG-RT1u) liver.

Tolerance of porcine renal allografts induced by donor spleen cells and seven days' treatment with cyclosporine.

Liver allografts in pigs and in rats elicit a substantial cellular immune response that can resolve spontaneously with the induction of donor-specific systemic tolerance. Self-limiting interactions between host and donor (graft)-derived leukocytes may be the basis for tolerogenesis. We have attempted to reproduce this effect of liver grafting in pigs by peroperative infusion of donor leukocytes into kidney graft recipients given an interrupted short course of CsA designed to promote donor leukocyte survival and interaction with host cells.

Distribution and persistence of antigen-presenting cells after intrathymic injection.

Intrathymic injection of donor immune cells has been shown by previous studies to prolong survival of rat allogeneic tissues. The aim of this pilot study was to assess the distribution and the persistence of intrathymically (i.t.

Does intrathymic injection of alloantigen-presenting cells before islet allo-transplantation prolong graft survival?

Current immunosuppressive agents have potentially dangerous side-effects, are non-specific and most are also diabetogenic. We investigated tolerance induction with intrathymic injection of purified antigen-presenting cells (APC) plus a single dose of antilymphocyte serum (ALS) intraperitoneally before allogeneic islet transplantation in the rat model WAG to Lewis (RT1u to RT1l). Purified donor APC [non-parenchymal cells (NPC) or dendritic cells (DC)] were prepared from liver and spleen, respectively.