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ICRA Noises: Artificial Noise Signals with Speech-like Spectral and Temporal Properties for Hearing Instrument Assessment: Ruidos ICRA: Señates de ruido artificial con espectro similar al habla y propiedades temporales para pruebas de instrumentos auditivos

Current standards involving technical specification of hearing aids provide limited possibilities for assessing the influence of the spectral and temporal characteristics of the input signal, and these characteristics have a significant effect on the output signal of many recent types of hearing aids. This is particularly true of digital hearing instruments, which typically include non-linear amplification in multiple channels. Furthermore, these instruments often incorporate additional non-linear functions such as “noise reduction” and “feedback cancellation”. The output signal produced by a non-linear hearing instrument relates to the characteristics of the input signal in a complex manner. Therefore, the choice of input signal significantly influences the outcome of any acoustic or psychophysical assessment of a non-linear hearing instrument. For this reason, the International Collegium for Rehabilitative Audiology (ICRA) has introduced a collection of noise signals that can be used for hearing aid testing (including real-ear measurements) and psychophysical evaluation. This paper describes the design criteria, the realisation process, and the final selection of nine test signals on a CD. Also, the spectral and temporal characteristics of these signals are documented. The ICRA noises provide a well-specified set of speech-like noises with spectra shaped according to gender and vocal effort, and with different amounts of speech modulation simulating one or more speakers. These noises can be applied as well-specified background noise in psychophysical experiments. They can also serve as test signals for the evaluation of digital hearing aids with noise reduction. It is demonstrated that the ICRA noises show the effectiveness of the noise reduction schemes. Based on these initial measurements, some initial steps are proposed to develop a standard method of technical specification of noise reduction based on the modulation characteristics. For this purpose, the sensitivity of different noise reduction schemes is compared by measurements with ICRA noises with a varying ratio between unmodulated and modulated test signals: a modulated-unmodulated ratio. It can be anticipated that this information is important to understand the differences between the different implementations of noise reduction schemes in different hearing aid models and makes. Los estándares actuales de las especificaciones técnicas de los auxiliares auditivos proporcionan posibilidades limitadas para conocer la influencia de las characterísticas temporales y espectrales de la señal de entrada y estas caracteristicas tienen un efecto significativo en la señal de salida de muchos tipos actuales de auxiliares auditivos. Esto es particularmente cierto en el caso de los instrumentos digitales, que típicamente presentan una amplification no lineal en canales multiples. Incluso, estos instrumentos a menudo incorporan funciones no lineales adicionales como la “reduction de ruido” y la “cancelatión de la retroalimentación”. La señal de salida producida por un instrumento no lineal se relaciona en una forma muy compleja con la señal de entrada, por lo que la selectión de la señal de entrada influye significativamente en la salida de cualquier prueba acustica o psicoaciistica de un instrumento auditivo. Por esta razón el Colegio International de Audiología Rehabilitatoria (ICRA) ha introducido una serie de señales de ruido que pueden ser utilizadas en las pruebas de auxiliares auditivos (incluyendo mediciones in-situ) y evaluaciones psicoacusticas. Este trabajo describe los criterios de diseño, el proceso de realizatión y la selectión final de 9 señales de prueba en un CD. También se describen las characterísticas espectrales y temporales de estas señales. Los ruidos ICRA son un conjunto muy específico de sonidos vocales con forma espectral acorde al género y el esfuerzo vocal y con diversas dosis de modulation vocal que simulan uno o más hablantes. Estos ruidos pueden ser utilizados como ruidos de fondo muy especificos en experimentos psicoacsticos. Tambien pueden servir como señales de prueba para evaluar auxiliares auditivos digitales con reductión de ruido. Se demuestra que los ruidos ICRA tienen la efectividad de los esquemas de reductión de ruido. Con base en estas mediciones iniciales, se proponen algunos pasos iniciales para desarrollar métodos estándar de las especificaciones técnicas de reductión de ruido tomando en cuenta las characterísticas de modulation. Para ello se compara la sensibilidad de diferentes esquemas de reductión de ruido mediante las mediciones de ruidos ICRA con un rango de variation entre senales de prueba modulares y no modulares. Se puede anticipar que esta informatión es importante para comprender las diferencias al implementar diferentes esquemas de reductión de ruido en diferentes modelos y tipos de auxiliares auditivos.

Prevalence of hearing loss in 1598 adults with an intellectual disability: Cross-sectional population based study

A cross-sectional epidemiological study on prevalence of hearing loss was carried out in an age- and Downs syndrome- stratified random sample of 1598 persons drawn from a base population of 9012 persons, representative of the Dutch adult population of intellectual disability (ID) service users. The re-weighted population prevalence is 30.3% (95% confidence interval [CI]: 27.7–33.0%). Subgroup prevalences range from 7.5% (95% confidence interval [CI]: 3.6–13.3) in the subgroup aged 18–30 years with ID by other causes than Downs syndrome, up to 100% (95% CI: 79.4–100%) in adults over 60 years of age with Downs syndrome. Downs syndrome (OR 5.18, 95% CI 3.80–7.07) and age were confirmed to be risk factors. Age-related increase in prevalence in persons with Downs syndrome appears to occur approximately three decades earlier, and in persons with ID by other causes approximately one decade earlier than in the general population. Sumario Se realizó un estudio epidemiológico transversal sobre hipoacusia con una muestra aleatoria estratificada por edad, en 1598 personas con síndrome de Down, tomadas de una población base de 9012 personas, representativas de los usuarios de servicios para discapacidad intelectual (ID) de adultos en Holanda. La prevalencia de población reconsiderada es de 30.3% (95% de intervalo de confianza revalorada [CI]: 27.7–33.0%). El rango de prevalencia de los subgrupos varió de 7.5% (95% de intervalo de confianza [CI]: 3.6–13.3) en el subgrupo de 18–30 años con ID por otras causas diferentes al S. de Down, hasta el 100% (95% CI: 79.4–100%) en adultos mayores a 60 años con S. de Down. El S. de Down (OR 5.18, 95% CI 3.80–7.07) y la edad se confirmaron como factores de riesgo. El incremento en la prevalencia relacionado con la edad en personas con S. de Down, parece ocurrir aproximadamente tres décadas más temprano y en personas con ID por otras causas, aproximadamente una década más temprano que en la población general.

Clinical evaluation of a full-digital in-the-ear hearing instrument.

In this study we measured the efficacy of a digital hearing aid with compression and noise reduction in a well-controlled clinical field trial in two independent centres. The experiments focused on a number of aspects of the application of the digital hearing aids. The study combines a field test of 2x4 weeks with laboratory experiments. We used objective measurements (speech perception tests in background noise, loudness scaling) and subjective assessments (questionnaires). The measurements were performed before and after the field test. The questionnaires were collected after each field test. The results of the digital hearing aids were compared to the results of similar tests with newly fitted analogue reference aids. The study involved 27 sensorineural hearing-impaired subjects, wearing new hearing aids. They comprised a representative sample of in-the-ear users. We used a crossover design in which the subjects used successively digital hearing aids and analogue reference aids in a randomized order. On average, the subjective data are more positive than the objective data. In the end, 20 out of 27 subjects had an overall preference for the digital hearing aid. The financial implications were not taken into consideration. However, objective data do not support this strong subjective preference. A reason could be that the method of analysis (short sentences in a short-duration background noise) is not suited for the digital hearing aid; the testing procedure does not allow the noise-reduction algorithm to adapt to the background noise. There was a striking difference between the results for the two centres. This difference can, to at least a certain extent, be attributed to the timing of speech relative to the background noise in the objective tests. This illustrates that the test conditions are critical in modern non-linear signal-processing hearing aids with long time constants. New evaluation techniques should be developed for this new generation of active non-linear hearing aids.

Self-reported disability and handicap after hearing-aid fitting and benefit of hearing aids: comparison of fitting procedures, degree of hearing loss, experience with hearing aids and uni- and bilateral fittings

Self-reported outcome on hearing disability and handicap as well as overall health-related quality of life were measured after hearing-aid fitting in a large-scale clinical population. Fitting was performed according to two different procedures in a double-blind study design. We used a comparative procedure based on optimizing speech intelligibility scores and a strictly implemented fitting formula. Hearing disability and handicap were assessed with the hearing handicap and disability inventory and benefit of hearing aids with the abbreviated profile of hearing aid benefit. Effects on health-related quality of life and depression were assessed with the EuroQol-5D questionnaire and the geriatric depression scale. We found that hearing-aid fitting according to either procedure had a significantly positive effect on disability and handicap associated with hearing loss. This effect lasted for several months. Only the effect on disability persisted after 1-year of follow-up. Self-reported benefit from hearing aids was comparable for both fitting procedures. Unaided hearing disability was more pronounced in groups of participants with greater hearing loss, while the benefit of hearing aids was independent from the degree of hearing impairment. First-time hearing aid users reported greater benefit from their hearing aids. The added value from a bilateral hearing-aid fitting was not significant. Overall health-related quality of life and incidence of depression did not alter after hearing-aid fitting.

Development of a Dutch matrix sentence test to assess speech intelligibility in noise

Abstract Objective: A Dutch matrix sentence test was developed and evaluated. A matrix test is a speech-in-noise test based on a closed speech corpus of sentences derived from words from fixed categories. An example is “Mark gives five large flowers.” Design: This report consists of the development of the speech test and a multi-center evaluation. Study sample: Forty-five normal-hearing participants. Results: The developed matrix test has a speech reception threshold in stationary noise of − 8.4 dB with an inter-list standard deviation of 0.2 dB. The slope of the intelligibility function is 10.2 %/dB and this is slightly lower than that of similar tests in other languages (12.6 to 17.1 %/dB). Conclusions: The matrix test is now also available in Dutch and can be used in both Flanders and the Netherlands.

How should hearing screening tests be offered

This paper deals with the question of how the general public should be addressed when offering hearing screening. Postal-based questionnaires in the United Kingdom, Germany, and the Netherlands were sent to users of hearing devices, those that are in the process of obtaining one, or those that have indicated that they have special interest in hearing. Results of the survey indicated that respondents were enthusiastic about the idea of being able to carry out hearing self-screening tests via the internet, telephone, or questionnaires. A questionnaire as a method to screen on hearing was generally preferred above using the internet, which was preferred over using the telephone for the test. About 27% of the respondents indicated to use exclusively one method. Most respondents indicated that either method provided would be of interest (41%), 17% indicated not to be interested in conducting screening tests using the internet.

Comparison of speech intelligibility in quiet and in noise after hearing aid fitting according to a purely prescriptive and a comparative fitting procedure

We compared two different types of hearing-aid fitting procedures in a double-blind randomized clinical study. Hearing aid fittings based on a purely prescriptive procedure (the NAL-RP formula) were compared to a comparative fitting procedure based on optimizing speech intelligibility scores. Main outcome measures were improvement of speech intelligibility scores in quiet and in noise. Data were related to the real-ear insertion responses that were measured after fitting. For analysis purposes subgroups were composed according to degree of hearing loss, characterized by unaided speech intelligibility in quiet, previous experience with hearing aids, unilateral or bilateral fittings and type of hearing aid. We found equal improvement of speech intelligibility in quiet, while fitting according to the prescriptive formula resulted in a somewhat better performance as expressed by the speech-to-noise ratio in comparison to the comparative procedure. Both procedures resulted in comparable real-ear insertion responses.

Combined sensory impairment (deaf-blindness) in five percent of adults with intellectual disabilities.

Our purpose in this cross-sectional study with 1,598 adult clients who had intellectual disabilities was to obtain valid prevalences of sensory impairments and to identify associations. The diagnoses were made through ophthalmologic and audiometric assessments, applying WHO/IASSID definitions. Re-weighted prevalences were 5.0% (95% CI 3.9- 6.2%) for the total adult population; 2.9% (1.9-4.1), less than 50 years; and 11.0% (7.9- 14.7), 50 years and over. Apart from being 50 years of age and over, p = .000, risk factors were more severe intellectual disability, p = .0001, and Down syndrome, p = .001. Results show that the risk of combined sensory impairment in this population is considerably increased compared with the general population. Part of the underlying conditions are treatable or can be rehabilitated. However, the complete diagnosis had been identified in only 12%.

Potential barriers and facilitators for implementation of an integrated care pathway for hearing-impaired persons: an exploratory survey among patients and professionals.

BackgroundBecause of the increasing costs and anticipated shortage of Ear Nose and Throat (ENT) specialists in the care for hearing-impaired persons, an integrated care pathway that includes direct hearing aid provision was developed. While this direct pathway is still under investigation, in a survey we examined expectations and potential barriers and facilitators towards this direct pathway, of patients and professionals involved in the pathway.MethodsTwo study populations were assessed: members of the health professions involved in the care pathway for hearing-impaired persons (general practitioners (GPs), hearing aid dispensers, ENT-specialists and clinical audiologists) and persons with hearing complaints. We developed a comprehensive semi-structured questionnaire for the professionals, regarding expectations, barriers, facilitators and conditions for implementation. We developed two questionnaires for persons with hearing complaints, both regarding evaluations and preferences, and administered them after they had experienced two key elements of the direct pathway: the triage and the hearing aid fitting.ResultsOn average GPs and hearing aid dispensers had positive expectations towards the direct pathway, while ENT-specialists and clinical audiologists had negative expectations. Professionals stated both barriers and facilitators towards the direct pathway. Most professionals either supported implementation of the direct pathway, provided that a number of conditions were satisfied, or did not support implementation, unless roughly the same conditions were satisfied. Professionals generally agreed on which conditions need to be satisfied. Persons with hearing complaints evaluated the present referral pathway and the new direct pathway equally. Many, especially older, participants stated however that they would still visit the GP and ENT-specialist, even when this would not be necessary for reimbursement of the hearing aid, and found it important that the ENT-specialist or Audiological Centre evaluated their hearing aid.ConclusionThis study identified professional concerns about the direct pathway for hearing-impaired persons. Gaps exist in expectations amongst professions. Also gaps exist between users of the pathway, especially between age groups and regions. Professionals are united in the conditions that need to be fulfilled for a successful implementation of the direct pathway. Implementation on a regional level is recommended to best satisfy these conditions.

Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71–40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the degree or steepness of the hearing loss. User preference and best performance in noise do not always coincide. Acclimatization may play a role. It could be advisable to let a user listen to a subjectively less favoured condition for at least some time if an optimal setting for speech intelligibility in noise is preferred over comfort. Sumario El objetivo de este estudio prospectivo fue evaluar los efectos de diferentes condiciones sobre la inteligibilidad del lenguaje en ruido, tanto objetiva como subjetivamente y determinar la mejor con-dición de parámetros de tiempo del programa pre-establecido (énfasis en alta frecuencia) o la com-binación para cada usuario en particular. Otro objetivo fue la evaluación de la relación entre las caracteristicas del paciente (p.ej. configuratión de la curva audiométrica) y las mejores condiciones. A un total de 38 sujetos divididos en 5 centros audiológicos se les adaptó una curveta digital Philips Spaceline D71–40. Se les pidió que compararan tres condiciones preestablecidas de algoritmos de compresión con diferentes constantes de tiempo: lenta (nombrado por el fabricante como AVC), intermedia (NORMAL) y rápida (SILÁBICA), durante dos periodos de 4 semanas de utilización de la condición intermedia, tanto en comparación como en uso aleatorio de las condiciones rápida y lenta. Se determinó aleatoriamente si el sujeto iniciaba con el programa confortable pre-establecido (AUTO) o con el programa orientado hacia la inteligibilidad del habla con énfasis en alta frecuencia (SPIN). En un tercer periodo de 4 semanas, se compararon los programas AUTO y SPIN utilizando las condiciones de compresión de constantes de tiempo que habian obtenido mejores resultados en los dos periodos iniciales. La comparación se efectuó mediante una prueba básica de lenguaje en ruido con tres tipos de ruido: continuo de bocina, modulado ICRA-4 y de automóvil. Además se le pidió a cada paciente que respondiera a una version traducida y adaptada al Holandés del cuestionario APHAB para indicar sus impresiones del desempeño. Los resultados muestran que no hay un algoritmo, pre-programación o com-binación más favorable en general. La condición que obtuvo mejores resultados de lenguaje en ruido fue la compresión silábica. Las ventajas del efecto del énfasis de la compresión de alta frecuencia después de la optimización de la compresión de tiempo son minimas. El cuestionario APHAB mostró que los usuarios tienden a preferir las condiciones de SPIN. No encontramos relación entre compresión favorecida o pre-establecida y el grado de inclinación de la curva audiométrica. No siempre coinciden las preferencias del usuario y el mejor desempeño en ruido. El proceso de adaptación puede influir. Podria ser recomendable permitir al usuario oir en una condición subjetivamente menos favorable al menos por un tiempo, si prefiere una programación optima para la inteligibilidad del lenguaje en ruido, sobre la confortable.