Speech recognition of hearing-impaired listeners: predictions from audibility and the limited role of high-frequency amplification.

Two experiments were conducted to examine the relationship between audibility and speech recognition for individuals with sensorineural hearing losses ranging from mild to profound degrees. Speech scores measured using filtered sentences were compared to predictions based on the Speech Intelligibility Index (SII). The SII greatly overpredicted performance at high sensation levels, and for many listeners, it underpredicted performance at low sensation levels.

Converting insertion gain to and from headphone coupler responses.

Objective: The paper aims to show how insertion gain responses can be translated into equivalent headphone responses, and vice versa.

Design: The relationship between the response types is theoretically derived by allowing for real ear to coupler differences and for real ear unaided responses.

Results: The necessary corrections for each of these factors are obtained from published data, and the combined correction factors are compared with independently obtained published data.

Development and evaluation of an inhalable bioaerosol manifold sampler.

This paper describes the development and evaluation of an inhalable bioaerosol manifold sampler for the collection of replicate samples over sequential sampling periods. Wind tunnel experiments at wind velocities < or = 0.6 m/sec (< or = approximately 120 ft/min) and at a sampling velocity of 0.

Client Oriented Scale of Improvement (COSI) and its relationship to several other measures of benefit and satisfaction provided by hearing aids.

Several methods for measuring the self-reported benefit and satisfaction provided by a hearing aid were compared by administering all methods to each of 98 subjects. Significant correlations between many of the measures and reasonably high test-retest correlations for two of the measures administered twice suggest that most of the measures provide valid estimates of benefit and/or satisfaction. One of the methods included is a new tool called the Client Oriented Scale of Improvement (COSI).

Guidelines for fitting multiple memory hearing aids.

Fitting guidelines to determine candidacy for multiple memory hearing aids and the choice of amplification for each memory are devised by reviewing studies on the selection of amplification for different listening conditions. The guideline for determining candidacy comprises three factors: (1) difficulty hearing in acoustically diverse conditions, (2) an average high-frequency hearing loss greater than about 55 dB HL, and (3) ability to vary the low-frequency gain by at least 5 dB. People who meet all three criteria are highly likely to benefit from multiple memories.

Gain, frequency response, and maximum output requirements for hearing aids.

This article applies the gain and frequency response and maximum output selection procedures currently recommended by the National Acoustic Laboratories (NAL) of Australia to the audiograms of a representative group of adult and child clients of Australian Hearing Services (AHS) to specify the performance that is required of various types of hearing aids in order to ensure that they can provide adequate gain, frequency response, and maximum output levels for at least 90% of the AHS client population. Cumulative frequency distributions of required 2-cc coupler gain slopes were calculated for each type of aid and used to design required frequency response variations. Coupler slope requirements in different octaves were found to be independent of one another.

An equivalent input noise level criterion for hearing aids.

The purpose of this project was to establish a maximum acceptable equivalent input noise level (EINL) for hearing aids. It was found that, if the version of the National Acoustic Laboratories (NAL) procedure for selecting the gain and frequency response of hearing aids, which includes modifications for severe and profound hearing loss is used, the EINL criterion can be relaxed for higher gain hearing aids, as a function of the gain of the aid. The relationship between relaxation of the criterion and 2-cc coupler gain is nonlinear, in different amounts, at the various frequencies, so no simple rule can be used to describe the manner in which the criterion can be relaxed.

Compression? Yes, but for low or high frequencies, for low or high intensities, and with what response times?

Several rationales for using compression in hearing aids are outlined. These rationales comprise discomfort avoidance, loudness normalization, noise reduction, short term signal dynamic range reduction, empirically determined compression, and long-term signal dynamic range reduction. The compression systems needed to implement each of these differ greatly, and these differences can be viewed as differences in the frequency range undergoing most compression, the intensity range undergoing most compression, and the speed at which the compressor(s) operate.

Candidates for multiple frequency response characteristics.

This study examined what types of subjects may benefit from the use of multiple memory hearing aids that offer variation in their frequency response characteristics. Thirty subjects with varied degrees and configurations of hearing loss compared an individually prescribed frequency response (NAL) and two variations in which the real-ear response slope was either increased (more high-frequency emphasis) or decreased by about 3 dB/octave over the range from 500 Hz to 4000 Hz. The evaluations consisted of paired comparison judgments of pleasantness and of ease of understanding speech, in quiet and in three background noises with substantially different acoustic spectra (traffic noise, speech babble, and high-frequency noise).

The effect of a depleting anti-CD4 monoclonal antibody on T cells and fetal pig islet xenograft survival in various strains of mice.

The effect of a cell-depleting anti-CD4 monoclonal antibody (mAb), GK1.5, was studied in a number of strains of inbred mice. Young adult female NOD/Lt, CBA and BALB/c mice were transplanted with organ cultured fetal pig pancreas and given 0.

Baseline body temperatures of patients with myelopathy.

In myelopathy patients, baseline body temperatures and effects of common ambient temperatures have not been measured. Oral (OT), rectal (ReT) and room (RmT) temperatures were measured between 5 and 7 A.M.

Virulence of two Streptococcus pyogenes strains (types M1 and M3) associated with toxic-shock-like syndrome depends on an intact mry-like gene.

The major virulence factor of Streptococcus pyogenes, the M protein, is positively regulated at the transcriptional level by mry in the M type 6 strain studied. We show here that in two S. pyogenes strains isolated from cases of toxic-shock-like syndrome, a type M1 strain and a type M3 strain, an mry-like gene is also required for resistance to phagocytosis.

Hearing aid evaluation: predicting speech gain from insertion gain.

In this study, hearing aid gain for speech was defined as the difference in level between the aided and unaided performance-intensity functions measured at any specific value of percentage of items correct. The articulation index method was used to predict speech gain based on the subject's unaided sound field thresholds, ambient room noise, hearing aid internal noise, hearing aid insertion gain, and the subject's unaided performance-intensity function. Predicted speech gain agreed with measured speech gain with rms errors of only 3 dB for 11 subjects with mild or moderate hearing loss tested with monosyllabic words and continuous discourse.

Cephalexin and penicillin in the treatment of group A beta-hemolytic streptococcal throat infections.

Objective: To determine whether cephalexin or penicillin is more effective in the treatment of group A beta-hemolytic streptococcal tonsillopharyngitis in children.

Design: Randomized, double-blind, crossover study conducted from 1981 to 1984.

Setting: Seven pediatric practices in the United States, including private offices and pediatric clinics.

Adherence of infected erythrocytes to venular endothelium selects for antigenic variants of Plasmodium falciparum.

Erythrocytes (E) infected with asexual forms of malaria parasites exhibit surface antigenic variation. In Plasmodium falciparum infections, the variant Ag is the P. falciparum E membrane protein 1 (PfEMP1).

Allowing for real ear venting effects when selecting the coupler gain of hearing aids.

Vents in hearing aids have two major effects on the insertion gain of a hearing aid: they let low-frequency sound in without amplification, and they reduce the low-frequency gain of sound transmitted through the hearing aid. Their net effect on low-frequency gain can thus be either negative or positive. This paper shows how to allow for both of these effects.

Group B streptococcal C protein-associated antigens: association with neonatal sepsis.

The c protein (Ibc) of group B streptococci (GBS) is associated with at least four antigens (alpha, beta, gamma, delta). To assess the virulence potential of these antigens, 255 GBS isolates recovered from septic neonates, healthy neonates, and pregnant women were serotyped and surveyed for reactivity with sera to c protein and the four associated antigens. A radioimmunoassay using intact bacteria was used to detect the GBS antigens.

Risk factors for perinatal group B streptococcal disease after amniotic fluid colonization.

A group of 1031 parturient women at high risk for intraamniotic infection were studied. Women in whom group B streptococci grew from cultures of the amniotic fluid did not differ in clinical risk factors when compared with similar parturient women without group B streptococcal colonization of amniotic fluid. Patients who had perinatal group B streptococcal disease (maternal or neonatal bacteremia) did not differ from those without disease, by maternal or neonatal acute antibody levels or antibody response, inoculum size, or serotype of the colonizing strain.

Epidemiological studies of Streptococcus pneumoniae in infants: antibody to types 3, 6, 14, and 23 in the first two years of life.

Antibodies to pneumococcal types 3, 6, 14, and 23 were measured in sera from 78 infants prospectively studied from birth. Mean levels of antibodies to capsular antigens were 2-4 micrograms/mL, with no overall differences between carriers and noncarriers of given types. Serial serum samples were studied in selected infants to more precisely define the antibody response in relation to specific pneumococcal colonization and infection.

Seroepidemiology of group B Streptococcus type II antibody specificity.

The specificity of human antibodies for the two major sidechain determinants of the type II group B streptococcal (GBS) polysaccharide was examined in 90 pairs of maternal and cord sera. Using an ELISA system, total antibody was measured against the complete (sialylated) type II antigen and the proportion of antibody against the galactose determinant was estimated by inhibition with free beta-methylgalactopyranoside. Mothers colonized by type II or by other GBS types had higher levels of total specific antibody (means, 3.