NAL-NL2 is the second generation of prescription procedures from The National Acoustic Laboratories (NAL) for fitting wide dynamic range compression (WDRC) instruments

Objective This study aimed to investigate 1) how a hearing aid needs to be adjusted for an adult who uses a cochlear implant in the contralateral ear; 2) whether the use of a hearing aid with a cochlear implant leads to interference; and 3) whether adults derive binaural benefits from using a hearing aid with a cochlear implant for speech perception, localization, and functional performance in everyday life. Design Twenty-one adults (11 female and 10 male) who used either a Nucleus CI-22 (N = 3) or a Nucleus CI-24 (N = 18) cochlear implant system in one ear participated in this study. Twelve of the adults were experienced hearing aid and implant users, whereas nine did not use a hearing aid after implantation. The hearing aids were fitted using the NAL-NL1 prescription, and fine-tuned for each individual by using a paired-comparisons test to identify the frequency response that was best for understanding speech, and a loudness balancing test to find the hearing aid gain that gave the same overall loudness as that perceived in the ear with a cochlear implant. Effects from using a hearing aid with a cochlear implant (bimodal hearing) were assessed by three measures. These included speech perception in noise in diotic and dichotic listening conditions, horizontal localization, and functional performance in everyday life. Performance with cochlear implant and hearing aid (CIHA) was compared with that with cochlear implant alone (CI) and hearing aid alone (HA). Results The NAL-NL1 prescribed appropriate frequency response slope on average, and the mean gain needed for binaural loudness balance was 4 dB lower than the prescribed gain. Individual variations in preferences suggest that it is desirable to fine-tune the hearing aid response slope and gain according to individual needs. The speech test results indicated that the CIHA scores were significantly better than the CI or the HA scores. Localization test results showed that the adults made significantly less error when locating a sound source using CIHA compared with CI or HA. Functional performance questionnaire scores for CIHA were significantly higher than CI scores or HA scores. All adults showed binaural benefits in at least one performance measure. On average, those who derived greater speech benefits also made less localization error and functioned more effectively in real life. Conclusions The results clearly indicate that binaural advantages can be obtained from using a hearing aid with a cochlear implant in opposite ears. It is recommended that bimodal stimulation be standard practice for rehabilitation of adults who wear unilateral cochlear implants. A hearing aid should be fitted to the nonimplanted ear using the NAL-NL1 prescription as a starting point, and the frequency response slope and gain could be fine-tuned to suit individual needs.

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. To improve predictive accuracy, the SII needed to be modified. Scaling the index by a multiplicative proficiency factor was found to be inappropriate, and alternative modifications were explored. The data were best fitted using a method that combined the standard level distortion factor (which accounted for decrease in speech intelligibility at high presentation levels based on measurements of normal-hearing people) with individual frequency-dependent proficiency. This method was evaluated using broadband sentences and nonsense syllables tests. Results indicate that audibility cannot adequately explain speech recognition of many hearing-impaired listeners. Considerable variations from audibility-based predictions remained, especially for people with severe losses listening at high sensation levels. The data suggest that, contrary to the basis of the SII, information contained in each frequency band is not strictly additive. The data also suggest that for people with severe or profound losses at the high frequencies, amplification should only achieve a low or zero sensation level at this region, contrary to the implications of the unmodified SII.

OBJECTIVES: Universal newborn hearing screening has been implemented to detect permanent childhood hearing loss (PCHL) early, with the ultimate goal of improving outcomes through early treatment. However, there is disagreement between studies on the size of this benefit and in some cases whether it is significantly different from 0. There have been no studies of sufficient size in which researchers have determined reliably whether the effect varies with degree of PCHL. We aimed to explore how intervention timing influences 5-year language in children with PCHL. METHODS: Via a prospective study of 350 children, we used standard multiple regression analyses to investigate the effect of age at intervention or hearing screening on language outcomes after allowing for the effects of nonverbal IQ, degree of PCHL, sex, birth weight, maternal education, additional disabilities, and communication mode. RESULTS: The benefit of early intervention for language development increased as hearing loss increased. Children whose amplification started at age 24 months had poorer language than those whose amplification started at 3 months. The difference was larger for 70-dB HL (−11.8 score points; 95% confidence interval [95% CI]: −18.7 to −4.8) than for 50-dB HL (−6.8; 95% CI: −10.8 to −2.8). Children who received cochlear implants at 24 months had poorer language than those implanted at 6 months (−21.4; 95% CI: −33.8 to −9.0). There was no significant effect of screening on outcomes. CONCLUSIONS: Early intervention improves language outcomes, thereby lending support to streamlining clinical pathways to ensure early amplification and cochlear implantation after diagnosis.

A new procedure for fitting nonlinear hearing aids (National Acoustic Laboratories' nonlinear fitting procedure, version 1 [NAL-NL1]) is described. The rationale is to maximize speech intelligibility while constraining loudness to be normal or less. Speech intelligibility is predicted by the Speech Intelligibility Index (SII), which has been modified to account for the reduction in performance associated with increasing degrees of hearing loss, especially at high frequencies. Prescriptions are compared for the NAL-NL1, desired sensation level [input/output], FIG6, and a threshold version of the Independent Hearing Aid Fitting Forum procedures. For an average speech input level, the NAL-NL1 prescriptions are very similar to those of the well-established NAL-Revised, Profound procedure. Compared with the other procedures, NAL-NL1 prescribes less low-frequency gain for flat and upward sloping audiograms. It prescribes less high-frequency gain for steeply sloping high-frequency hearing losses. NAL-NL1 tends to prescribe less compression than the other procedures. All procedures differ considerably from one another for some audiograms. Abbreviations: Al = Articulation Index, CR = compression ratio, CT = compression threshold; DSL[i/o] = desired sensation level [input/output], IHAFF = Independent Hearing Aid Fitting Forum, LGOB = loudness growth in ¹/₂-octave bands, NAL-NL1 = National Acoustic Laboratories' nonlinear fitting procedure, version 1, NAL-R = NAL Revised, NAL-RP = NAL-Revised, Profound, PLL = preferred listening level, POGO = prescription of gain and maximum output, RAB = Ricketts and Bentler, rms = root mean square, SII = Speech Intelligibility Index, WDRC = wide dynamic range compression Article published online: 28 February 2022 © 2001. American Academy of Audiology. This article is published by Thieme. Thieme Medical Publishers, Inc. 333 Seventh Avenue, 18th Floor, New York, NY 10001, USA

Objective: To address the question of whether, on a population level, early detection and amplification improve outcomes of children with hearing impairment. Design: All families of children who were born between 2002 and 2007, and who presented for hearing services below 3 years of age at Australian Hearing pediatric centers in New South Wales, Victoria, and Southern Queensland were invited to participate in a prospective study on outcomes. Children’s speech, language, functional, and social outcomes were assessed at 3 years of age, using a battery of age-appropriate tests. Demographic information relating to the child, family, and educational intervention was solicited through the use of custom-designed questionnaires. Audiological data were collected from the national database of Australian Hearing and records held at educational intervention agencies for children. Regression analysis was used to investigate the effects of each of 15 predictor variables, including age of amplification, on outcomes. Results: Four hundred and fifty-one children enrolled in the study, 56% of whom received their first hearing aid fitting before 6 months of age. On the basis of clinical records, 44 children (10%) were diagnosed with auditory neuropathy spectrum disorder. There were 107 children (24%) reported to have additional disabilities. At 3 years of age, 317 children (70%) were hearing aid users and 134 children (30%) used cochlear implants. On the basis of parent reports, about 71% used an aural/oral mode of communication, and about 79% used English as the spoken language at home. Children’s performance scores on standardized tests administered at 3 years of age were used in a factor analysis to derive a global development factor score. On average, the global score of hearing-impaired children was more than 1 SD below the mean of normal-hearing children at the same age. Regression analysis revealed that five factors, including female gender, absence of additional disabilities, less severe hearing loss, higher maternal education, and (for children with cochlear implants) earlier age of switch-on were associated with better outcomes at the 5% significance level. Whereas the effect of age of hearing aid fitting on child outcomes was weak, a younger age at cochlear implant switch-on was significantly associated with better outcomes for children with cochlear implants at 3 years of age. Conclusions: Fifty-six percent of the 451 children were fitted with hearing aids before 6 months of age. At 3 years of age, 134 children used cochlear implants and the remaining children used hearing aids. On average, outcomes were well below population norms. Significant predictors of child outcomes include: presence/absence of additional disabilities, severity of hearing loss, gender, maternal education, together with age of switch-on for children with cochlear implants.