PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9170712

Recent developments in air-conduction hearing aids.

S Arlinger
View original source ↗Export metadata ↓

Abstract

From a history of hearing aids based on analog signal processing, the door has just opened to a new "room," the digital hearing aid room. Previously, the more complex signal processing schemes could be tested only at the lab and rarely in real-life environments. The advent of wearable digital hearing aids primarily means that we have much more powerful tools available now, allowing us to test various ideas for signal processing in true field tests over sufficient durations. Since the different processing schemes will be controlled by software (the program or algorithm that has been stored in the hearing aid), we will be able to design truly blind field tests for the comparison of different processing, thereby avoiding the bias for the new aid versus the old aid which has always plagued clinical trials of hearing aids thus far. It is not very likely that the digital era in hearing aids will solve all problems in a short time. I am convinced that we have just started on a slow process into this "digital room." What, precisely, we will find there of value is hard to tell, but I am equally convinced that the main effects will be of noticeable benefit to the user. It is also very likely that some of the lessons we will learn in our future digital experiments will be useful not only for air-conduction hearing aids, but also for other types of technical aids for the hearing-impaired and the deaf.

Explore related subjects

AirEquipment DesignHearing AidsHearing Loss, SensorineuralHumansSignal Processing, Computer-AssistedSoftwareSpeech PerceptionJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S Arlinger. 1997. Recent developments in air-conduction hearing aids.. https://pubmed.ncbi.nlm.nih.gov/9170712/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2001

Grass-air exchange of polychlorinated biphenyls.

Three field experiments were performed to assess the clearance, uptake, and exchange kinetics of polychlorinated biphenyls (PCBs) between grass and the atmosphere using mixed- and single-species grass (Holcus lanatus). In the clearance experiment, the grass was artificially contaminated by equilibration with diluted Aroclor vapor then exposed to field air, and the rates of depletion were monitored by sampling at regular intervals to determine clearance rate constants. In the uptake experiment, the uptake of PCBs from the ambient atmosphere was followed in growing grass at ambient concentrations for 3 and 6 weeks by analysis of segmented samples along the length of the sward. In the third experiment, diurnal temperature-driven changes in grass concentrations were measured. The results indicate that the grass is behaving as a two-compartment system: (1) a fast-exchanging surface adsorption site with a response time of hours and a capacity essentially independent of K(OA), the octanol-air partition coefficient and (2) a slow responding site with a response time of weeks, the capacity of which is related to K(OA). The kinetic and equilibrium phenomena involved in grass-air exchange are thus complex and are not adequately described by simple first-order rate constants and equilibrium partitioning coefficients.

Air↗
PubMed2001

Multiclass/multiresidue method for monitoring widely applied plant protecting agents in air during field dispersion work.

A multiclass/multiresidue method for surveying the uptake of plant protecting chemicals by inhalation during field spraying work is described. Eleven nowadays mainly dispersed compounds, which cover a wide range of chemical properties, are analysed in air with personal active sampling and in one single analytical run. This has the advantage, that one basic method only needs to be implemented, calibrated and validated in a laboratory to perform varying monitoring tasks without changing the method itself. Samples were taken with Tenax sorbent tubes operated to collect the active compounds simultaneously in the vapour state, in aerosol state or bound to particles. The procedure consists of four unit operations only: sampling, elution, dilution and HPLC measurement, and is described in SOP-format. The limits of quantification, calculated as method detection limits, were between 1 and 9 microg m(-3) based on 1 m3 air volume sampled (8 h). Method performance was characterised by way of generated test atmospheres and field spraying trials.

Air↗
PubMed2001

Characteristics and sequence of phosphoglycolate phosphatase from a eukaryotic green alga Chlamydomonas reinhardtii.

Phosphoglycolate phosphatase (PGPase), a key enzyme of photorespiration in photosynthetic organisms, was purified from Chlamydomonas reinhardtii. The enzyme was an approximately 65-kDa homodimer with a pI value of 5.1 composed of approximately 32-kDa subunits not connected by any S-S bridges. It was also highly specific for phosphoglycolate with a K(m) value of 140 microm and an optimal pH between 8 and 9. The activity was strongly inhibited by CaCl(2), and it recovered competitively following the addition of MgCl(2) or EGTA. A mobility shift was observed in SDS-polyacrylamide gel electrophoresis by the addition of CaCl(2), indicating that the enzyme binds to Ca(2+). The N-terminal region of amino acid sequence deduced from cDNA sequence that was not contained in the purified PGPase had similar characteristics to those of typical stroma-targeting transit peptides in C. reinhardtii. The following region of the deduced sequence containing 302 amino acid residues was similar to p-nitrophenylphosphatase-like proteins, although the purified PGPase did not hydrolyze p-nitrophenylphosphate. Genomic DNA fragments from wild type containing the sequence homologous to the cDNA for PGPase complemented the PGPase-deficient mutant pgp1. Possible regulatory mechanisms during adaptation to limiting CO(2) were discussed based on the characteristics of the purified PGPase and the deduced amino acid sequence.

Air↗