Introduction to the Special Issue: Select Papers From the Hearing Across the Lifespan (HEAL) 2018 Conference.

[Figure: see text].

Reflections on Lake Como Conferences (2000-2016).

PURPOSE: We present an overview of the conceptualization and development of the Newborn Hearing Screening and Hearing Across the Lifespan (Lake Como) conferences from 2000 to 2016.

A user-operated test of suprathreshold acuity in noise for adult hearing screening: The SUN (Speech Understanding in Noise) test.

A novel, user-operated test of suprathreshold acuity in noise for use in adult hearing screening (AHS) was developed. The Speech Understanding in Noise test (SUN) is a speech-in-noise test that makes use of a list of vowel-consonant-vowel (VCV) stimuli in background noise presented in a three-alternative forced choice (3AFC) paradigm by means of a touch sensitive screen. The test is automated, easy-to-use, and provides self-explanatory results (i.e., 'no hearing difficulties', or 'a hearing check would be advisable', or 'a hearing check is recommended'). The test was developed from its building blocks (VCVs and speech-shaped noise) through two main steps: (i) development of the test list through equalization of the intelligibility of test stimuli across the set and (ii) optimization of the test results through maximization of the test sensitivity and specificity. The test had 82.9% sensitivity and 85.9% specificity compared to conventional pure-tone screening, and 83.8% sensitivity and 83.9% specificity to identify individuals with disabling hearing impairment. Results obtained so far showed that the test could be easily performed by adults and older adults in less than one minute per ear and that its results were not influenced by ambient noise (up to 65dBA), suggesting that the test might be a viable method for AHS in clinical as well as non-clinical settings.

Introduction to the AJA research forum on aging and hearing: mechanisms and effects.

PURPOSE This Research Forum, "Aging and Hearing: Mechanisms and Effects," highlights 6 contributions presented at the 2nd International Conference on Adult Hearing Screening (AHS 2012), held in Cernobbio (Lake Como, Italy) in June 2012. Overall, the articles in this Research Forum give insight into the causes, mechanisms, and consequences of auditory dysfunctions in adults, with particular focus on their implications for screening, assessment, and intervention.

Introduction to the AJA research forum on intervention and rehabilitation strategies for adults and older adults.

PURPOSE To give an overview of the third in a series of research forums emerged from the second International Conference on Adult Hearing Screening (AHS 2012), which was held in Cernobbio (Lake Como, Italy) in June 2012. The first two research forums, published in the previous and current issues of this journal, included several key contributions from the AHS meeting in 2 major topic areas, "Hearing Screening in Adults and Older Adults" (Vol. 22, June 2013) and "Aging and Hearing: Mechanisms and Effects" (this issue). In the 7 articles showcased in this Research Forum on "Intervention and Rehabilitation Strategies for Adults and Older Adults," the authors provide a multifaceted view on recent advancements in intervention strategies for adults with hearing loss, with ample emphasis on auditory training; discuss the research challenges that need to be tackled in this field; and explore new ways to take into account the individual needs and obtain a deeper understanding of the peculiar attributes of hearing in older adults.

Introduction to the AJA research forum on hearing screening in adults and older adults.

PURPOSE: To illustrate the overall project that led to the development of a series of research forums highlighting several key contributions to AHS 2012, the 2nd International Conference on Adult Hearing Screening, in Cernobbio (Lake Como), Italy, and, in particular, to provide an overview of the first research forum, "Hearing Screening in Adults and Older Adults," which contains a set of brief papers that tackle prominent issues related to adult hearing screening: guiding principles for adult screening, development of methods and technologies, program implementation and evaluation, possible future scenarios, and health policy issues.

Using the speech understanding in noise (SUN) test for adult hearing screening1.

PURPOSE: To develop a novel speech-in-noise test for adult hearing screening-the Speech Understanding in Noise (SUN) test. The goal was to design a fast, automated, easy-to-use test to identify difficulties in speech communication. METHOD: The SUN test consists of a short list of intervocalic consonants in noise presented in a forced-choice paradigm by means of a touch screen. The SUN test was developed and evaluated in an overall population of >6,000 participants. The test is available in various languages (i.e., English, French, German, and Italian) and continues to be developed in others (e.g., Spanish, Portuguese, and Mandarin). RESULTS: Test time was <1 min/ear. Test-retest reliability was very good. The test showed good agreement with conventional clinical measures (e.g., pure-tone testing, speech-in-noise testing, and self-reported hearing handicap). The test's sensitivity and specificity to identify disabling hearing impairment were 84% and 75%, respectively. The same results were obtained in low and high ambient noise. CONCLUSION: The SUN test is fast, repeatable, easy to use, self-explanatory, specific to the impairment, and robust to ambient noise. It may be a viable approach for adult hearing screening in clinical as well as nonclinical settings.

Interventions following hearing screening in adults: a systematic descriptive review.

OBJECTIVE: Adult hearing screening may be a solution to the under-diagnosis and under-treatment of hearing loss in adults. Limited use and satisfaction with hearing aids indicate that consideration of alternative interventions following hearing screening may be needed. The primary aim of this study is to provide an overview of all intervention types that have been offered to adult (≥ 18 years) screen-failures. DESIGN: Systematic literature review. Articles were identified through systematic searches in PubMed, EMBASE, Cinahl, the Cochrane Library, private libraries, and through reference checking. RESULTS: Of the initial 3027 papers obtained from the searches, a total of 37 were found to be eligible. The great majority of the screening programmes (i.e. 26) referred screen-failures to a hearing specialist without further rehabilitation being specified. Most of the others (i.e. seven) led to the provision of hearing aids. Four studies offered alternative interventions comprising communication programme elements (e.g. speechreading, hearing tactics) or advice on environmental aids. CONCLUSIONS: Interventions following hearing screening generally comprised referral to a hearing specialist or hearing aid rehabilitation. Some programmes offered alternative rehabilitation options. These may be valuable as an addition to or replacement of hearing aid rehabilitation. It is recommended that this be addressed in future research.

Modeling of the internal fields distribution in human inner hearing system exposed to 900 and 1800 MHz.

This paper investigates the internal electric and magnetic field distribution and the specific absorption rate (SAR) values in a magnetic resonance imaging-based model of the inner hearing system exposed to 900 and 1800 MHz. The internal fields distributions were calculated using the Finite Integration Technique. The estimation of the field values was evaluated along lines passing through that target organ, specifically from the vestibular to the cochlear region and from the apex to the base of the cochlea. The specific findings are: 1) higher internal fields strength and SAR value in the vestibular region rather than in the auditory region, especially for the inner ear closer to the external source; 2) higher internal fields strength in the basal and apical region of the cochlea than in the middle one; 3) local differences in the internal fields distribution and SAR value, comparing the head models including or not the inner auditory system model; 4) results' variability evaluated by changing the head-source mutual position and the dielectric properties of the inner hearing system.

Speech processing for cochlear implants with the discrete wavelet transform: feasibility study and performance evaluation.

An innovative approach is investigated for speech processing in cochlear implants (CI). Differently from the traditional filter-bank spectral analysis strategies, the proposed method analyses the speech signal by means of the discrete wavelet transform (DWT). Preliminary tests were conducted in order to compare the WT and the filter-bank analysis methods. Additionally, the intelligibility of the speech processed with the proposed WT strategy was tested on normal hearing people by means of the acoustic simulations and a comparison was made with respect to traditional CI algorithms. Results showed that the WT could be a suitable method for speech coding in CIs. The information loss was minimal and, in speech recognition tests, the WT performance was similar to traditional filter-bank strategies.

Otoacoustic emission latency, cochlear tuning, and hearing functionality in neonates.

Transient evoked otoacoustic emissions of a large population of neonates (466 ears) are analyzed, with the aim of establishing if a significant latency difference can be observed between "pass" (333) and "fail" (133) ears, discriminated with a screening protocol based on band and global reproducibility. The ears that did not pass the test in at least one frequency band are named "fail," for simplicity, but they should be more appropriately defined as "partial pass." In a previous study, significantly different average latencies had been observed in adult subjects, comparing normal hearing and hearing impaired ears [J. Acoust. Soc. Am. 111, 297-308 (2002)], but no similar study has been conducted on neonates yet. An improved wavelet technique was applied to transient evoked otoacoustic emission data, to get accurate experimental measurements of the otoacoustic emission latency. The results show statistically significant differences between the latency distributions of the "pass" and "fail" populations, with the "fail" latencies longer. However, non-Gaussianity of the distributions and systematic errors associated with low reproducibility levels suggested using a conservative approach in the data analysis and interpretation. New otoacoustic estimates of cochlear tuning in neonates are also provided.

The Milan Project: a newborn hearing screening programme.

AIM: Since 1997 a newborn hearing screening programme has been implemented by the U.O. Neurologia-Neurofisiopatologia and Dipartimento di Neonatologia of the Istituti Clinici di Perfezionamento ICP in Milan for both babies with no risk and those at risk of hearing impairment. This programme was named the Milan Project. METHODS: The protocol for no-risk babies consisted of three stages: in the first two stages, newborns were tested with transient click-evoked otoacoustic emissions (TEOAE), in the third one with conventional auditory brainstem responses (ABR). The first TEOAE test was performed by 36 h of age, before discharge, the second one after 15-30 d in case of referral, and the third one, by ABR, for those babies who failed the second TEOAE stage. Newborns at audiological risk were submitted to conventional ABR before the third month of corrected age. Some of this latter population was also submitted to the TEOAE test. The entire tested population (no-risk babies and newborns at audiological risk) consisted of 19 777 babies: 19 290 without risk ("no risk") and 487 at risk ("at risk"). RESULTS: During the course of the Milan Project, hearing impairment (ABR threshold equal to or greater than 40 dB nHL) was identified in 63 newborns (19 from the no-risk and 44 from the at-risk population), with a prevalence of 0.32%. Bilateral hearing impairment (BHI) was found in 33 newborns (10 from the no-risk and 23 from the at-risk population), corresponding to 0.17%. Among infants with bilateral hearing impairment, 30.3% had no risk factors. The prevalence of hearing impairment was determined on days 15-30 after birth. CONCLUSIONS: The results show that the implementation of a hospital-based, universal neonatal hearing screening programme for babies with and without audiological risk is feasible and effective. The effectiveness of the programme has increased as a function of the years since its inception, with a strong decrease in the referral rate. Further improvement is obtained if the TEOAE measurements are repeated in cases of referral scoring before discharge.

Cochlear maturation and otoacoustic emissions in preterm infants: a time-frequency approach.

Click-evoked otoacoustic emissions (CEOAEs) from preterm infants were analyzed to characterize developmental changes of cochlear active mechanisms. Due to their strong time-varying properties, CEOAEs were studied with a time-frequency approach--the wavelet transform (WT). By means of the WT, CEOAEs were decomposed into 12 frequency bands, spanning the 0.25-6.25 kHz range. For each band, the root-mean-square (RMS) level and latency were studied as functions of both frequency and age. Because CEOAEs were averaged using the non-linear mode of acquisition, the developmental changes in observed in this study are related to the non-linear component (which is actually the most predominant component of the active cochlear response) of CEOAEs, the linear one being mostly canceled out by non-linear averaging. In our study, there was evidence that properties of CEOAE non-linear components are related to the post-conception age (PCA) in that the levels and latency of CEOAE frequency components changed until the age of about 38 weeks post-conception, whereas after 38 weeks, CEOAE features were very similar to those of term newborns. In particular, the CEOAE levels increased and latency decreased with age. The observed changes in CEOAE properties seem to reveal a development of cochlear active mechanisms, although contributions from outer and middle ear development cannot be excluded. Also, in agreement with previous physiological and behavioral findings, our results revealed that the development of CEOAE properties was not the same for all the frequencies, being greater for frequencies 4 kHz, and resembled the development of the cochlear partition, which proceeds from base to apex.

Design of hearing aid shells by three dimensional laser scanning and mesh reconstruction.

Hearing aid shells (or earmolds) must couple the hearing aid with the user's ear. Earmolds have to fit the subject's outer ear canal properly to ensure a good performance of the aid. Because of the great variability in the anatomical pattern of the ear, earmolds are custom made. At present, an impression of the subject's ear canal is taken and used to fabricate the silicon-made mold. The postimpression activities that typically are performed during the fabrication process modify the physical dimensions of the resulting earmold and thus affect the fit of the product. A novel system for 3-D laser scanning and mesh reconstruction of the surface of ear canal impressions is presented. The reconstructed impression can be digitally stored and passed directly to dedicated CAD 3-D printing machines to model the silicon earmold and thus achieve the best possible fit. The proposed system is based on a couple of cameras and a commercial laser for the surface digitization and on a straightforward algorithm, based on the deformation of a geometric model, for the reconstruction of the acquired surface. Measurements on objects of well-known geometric features and dimensions are performed to assess the accuracy and repeatability levels of this 3-D acquisition system. Robustness to noise of the proposed reconstruction algorithm is determined by simulations with a synthetic test surface. Finally, the first measurements (acquisition+reconstruction) of closed surfaces from ear canal impressions are reported.

Principal component analysis as a method to facilitate fast detection of transient-evoked otoacoustic emissions.

Transient-evoked otoacoustic emissions (TEOAE) are acoustic signals coming from the inner ear (outer hair cells of the cochlea) after acoustic stimulation by clicks. They can be used to investigate the status of the peripheral hearing system. Some of their potential applications (e.g., their use as a tool in newborn hearing screening programs) are deeply related to the duration of each recording session. This duration can be strongly reduced by applying a principal component analysis approach to a set of TEOAE recorded from the same ear at different stimulus levels averaging only a few sweeps (a maximum of 100 versus the classical 260). The PCA approach is shown to be able to enhance the signal-to-noise ratio and, in turn, to allow a correct detection of the responses. Results of the application of this approach in comparison with responses recorded from the same subjects with the classical technique will be shown.

Comparison of two methods of TEOAE recording in newborn hearing screening.

This paper summarizes the results of trials performed in two hospitals, comparing the scoring of transient evoked otoacoustic emissions (TEOAEs) on the same neonates and within the same test session, recorded by the fully automatic device EchoScreen (Madsen Electronics/Fischer-Zoth GmbH) and ILO Otodynamics Ltd system. These trials form part of a larger project (Project Sentinel), whose primary aim is to stimulate the creation of new neonatal hearing screening programmes. Four thousand two hundred and forty-eight neonates were tested with both devices (8494 ears), in randomized order. The response scores obtained with the two devices are in full agreement in 98.72% of the tested ears. Considering the recording time, the fully automatic Echo Screen was, on average, about 3.6 times faster than the ILO88, bearing in mind, however, that when using ILO88, the end of the recording is decided by the operator on the basis of some mandatory decision rules.

Click-evoked otoacoustic emissions recorded from untreated congenital hypothyroid newborns.

Thyroid hormone plays an important role in hearing development. Both a genetic or non-genetic hypothyroidism is often associated with congenital hearing loss. The exact incidence of hearing impairment in untreated congenital hypothyroid (CH) patients is unknown. This paper will present the results of measuring of the transient-evoked otoacoustic emissions (TEOAE) in a population of 29 newborns, who tested positive on a screening test for hypothyroidism (CH group) and in 68 well babies (control group) randomly chosen from all the newborns, classified as PASS, included in the Hearing Screening Program of the San Raffaele Hospital in Milan. TEOAE were recorded in all newborns within 1 month after birth and before beginning L-thyroxine treatment with conventional commercial instrumentation. Both temporal and time-frequency analyses of the emitted responses were conducted by means of a wavelet transform. The comparison of the characteristics of the temporal and frequency content of the responses of the two groups (CH and control) showed no statistically significant difference. No correlation was found between outer hair cell dysfunction and hypothyroidism.

Frequency-related effects in the optimization of coils for the magnetic stimulation of the nervous system.

Magnetic stimulation of the nervous system is a non-invasive technique with a large number of applications in neurological diagnosis, brain research, and, recently, therapy. New applications require engineering modifications in order to decrease power consumption and coil heating. This can be accomplished by optimized coils with minimized resistance. In this study the influence of some frequency-related effects (skin and proximity effect) on the coil resistance will be discussed, together with the role played by wire shape, wire section, and twisting effect. The results show that the coil resistance increases with frequency. As an example, for a 20-mm2 circular wire section, the skin effect in the typical frequency range of magnetic stimulator devices (2-4 kHz) increases the coil resistance up to about 45% with respect to its dc value. Moreover, the influence of the frequency is lower for flat wire sections and reasonably small helix twist angle of the coil.