Tammo Houtgast

Development and validation of an automatic speech-in-noise screening test by telephone

To meet the need for an objective self-test for hearing screening, a new Dutch speech-in-noise test was developed. Digit triplets were used as speech material. The test was made fully automatic, was controlled by a computer, and can be done by telephone. It measures the speech reception threshold (triplet SRTn) using an adaptive procedure, in about 3 min. Our experiments showed no significant influence of telephone type or listening environment. Measurement errors were within 1 dB, which makes the test accurate. In additional experiments with hearing-impaired subjects (76 ears of 38 listeners), the new test was compared to the existing sentence SRTn test of Plomp and Mimpen, which is considered to be the standard. The correlation between both SRTns was 0.866. As expected, correlations between the triplet SRTn test by telephone and average pure-tone thresholds are somewhat lower: 0.732 for PTA0.5, 1, 2, and 0.770 for PTA0.5, 1, 2,4. When proper SRTn values were chosen for distinguishing between normal-hearing and hearingimpaired subjects, the triplet SRTn test was found to have a sensitivity of 0.91 and a specificity of 0.93. Sumario Para satisfacer la necesidad de un test objetivo de autoevaluacio´n para identificacio´n de problemas auditivos, se desarrollo´ una nueva prueba holandesa de lenguaje en ruido. Se utilizaron cifras de tres di´gitos como material logoaudiome´trico. El test se hizo totalmente automa´tico, controlado por una computadora y realizable por tele´fono. Mide el umbral de recepcio´n del lenguaje (SRTn triplet) en 3 minutos, utilizando un procedimiento adaptativo. Nuestras pruebas no muestran una influencia significativa del tipo de tele´fono o del ambiente de la prueba. Los errores de medicio´n no variaron en ma´s de 1 dB, lo que hace que la prueba sea exacta. En experimentos adicionales con sujetos hipoacu´sicos (76 oi´dos de 36 sujetos), la nueva prueba se comparo´ con el test de SRTn con frases de Plomp y Mimpen, considerado como el esta´ndar de referencia. La correlacio´n entre los SRTnfue de 0.866. Como se esperaba, la correlacio´n entre la prueba telefo´nica de SRTncon di´gitos triples y el promedio de umbrales tonales puros es un poco ma´s baja: 0.732 para el PTA0.5, 1, 2 y 0.770 para el PTA0.5, 1, 2, 4. Cuando se escogieron los valores apropiados de SRTnpara distinguir entre sujetos normo-oyentes e hipoacu´sicos, la prueba de SRTncon di´gitos triples demostro´ una sensibilidad de 0.91 y una especificidad de 0.93.

Occupational performance: Comparing normally-hearing and hearing-impaired employees using the Amsterdam Checklist for Hearing and Work

This study compares the occupational performance of employees with and without hearing impairment, and aims to identify occupational difficulties specifically related to hearing loss. The Amsterdam Checklist for Hearing and Work was administered to 150 hearing-impaired employees and 60 normally-hearing colleagues. A multivariate analysis of variance was performed to test group effects, and to examine differences between means. Factors predicting sick-leave were identified by regression analyses. A significant group effect (pu200a<u200a0.01) was found. Hearing-impaired employees differed from normally-hearing colleagues in their perception of ‘environmental noise’, ‘job control’ and the ‘necessity to use hearing activities’ at work. Also, sick-leave due to distress occurred significantly more often in the hearing impaired group (pu200a<u200a0.05). ‘Hearing impairment’, ‘job demand’, and the requirement to ‘recognize/distinguish between sounds’ were the strongest risk-factors for stress related sick-leave. The importance of hearing functions besides speech communication is discussed. Implications for rehabilitation are suggested. In future research, hearing loss should be considered as a risk factor for fatigue and mental distress which may lead to sick-leave. Sumario Este estudio compara el desempeño ocupacional de empleados con y sin trastorno auditivo y busca identificar dificultades laborales específicamente relacionadas con la hipoacusia. Se administró el Listado de Amsterdam para Audición y Trabajo a 150 trabajadores con trastornos auditivo y a 60 colegas normo-oyentes. Se realizó un análisis multivariado de varianza para evaluar efectos de grupo y para examinar diferencias entre las medias. Se identificaron los factores para predecir incapacidades por enfermedad por medio de análisis de regresión. Se encontró un significativo efecto de grupo (pu200a<u200a0.01. Los trabajadores hipoacúsicos fueron diferentes de los normo-oyentes en su percepción del “ruido ambiental”, del “control laboral” y de la “necesidad de utilizar actividades auditivas” en el trabajo. También, las incapacidades debidas a tensión ocurrieron significativamente más a menudo en el grupo de hipoacúsicos (pu200a<u200a0.05). Los “trastornos auditivos”, las “demandas del trabajo” y el requisito de “reconocer/distinguir sonidos” fueron los factores de riesgo más importantes para las incapacidades relacionadas con el estrés. Se discute la importancia de las funciones auditivas más allá de la comunicación por lenguaje. Se sugieren las implicaciones para la rehabilitación. En investigaciones futuras, la hipoacusia debe ser considerada como un factor de riesgo para fatiga y tensión mental que pueden conducir a incapacidades por enfermedad.

On the auditory and cognitive functions that may explain an individual's elevation of the speech reception threshold in noise

It is generally recognized that poor results of speech-in-noise tests by hearing-impaired persons cannot be fully explained by the elevated pure-tone hearing threshold. Plomp has shown, among others, that an additional factor has to be taken into account, often referred to in general terms as distortion. In an attempt to specify auditory and cognitive functions which may underlie this distortion, various studies on this topic originating from Plomps research group are reviewed, as well as other relevant studies which provide quantitative data on the correlations between various types of auditory or cognitive tests (the predictor tests) and speech-in-noise tests. The predictor variables considered include, besides the pure-tone audiogram, measures of spectral and temporal resolution, intensity difference limen, age, and some cognitive aspects. The results indicate that, by and large, these variables fall short in fully explaining the variance observed in the speech-in-noise tests. This strongly suggests that the predictor variables considered so far do not cover all sources of variance relevant for speech reception in noise.

Results from the Dutch speech-in-noise screening test by telephone

Objective: The objective of the study was to implement a previously developed automatic speech-in-noise screening test by telephone (Smits, Kapteyn, & Houtgast, 2004), introduce it nationwide as a self-test, and analyze the results. Design: The test was implemented on an interactive voice response system, which can handle multiple lines. The test measures the speech reception threshold in speech-shaped noise by telephone (SRTTn) in an adaptive procedure using digit triplets as speech material. The test result is given as either good, insufficient, or poor. Questions about age, sex, and subjective rating of hearing were included in the test. The test was introduced as the National Hearing test and publicity was generated. In the first 4 mo, 65,924 people took the initiative and dialed the test. The possibility to use mobile phones was disabled because of significant worse results (0.7 dB) with that telephone type. Results: After applying exclusion criteria, results from 39,968 callers were analyzed. Seventy-five percent of the callers were older than 44 yr of age. Starting at about 45 yr of age, there is an increase in SRTTn with increasing age. SRTTns for men are significantly worse than SRTTns for women for age groups 50 to 54 and higher. Older people tend to rate their hearing better than might be expected from their SRTTn. However, after converting the mean SRTTn values per age group and per subjective score to percentile values, the values remain constant across age groups. Mean measurement error was within 1 dB. These errors increase with increasing SRTTn. Conclusions: This study shows the implementation and results from a functional hearing screening test by telephone. The test can be done in about 3 minutes, 30 sec, including introductory text, explanation of the test procedure, test result, and recommendation for audiological evaluation. The high number of callers implies that the test is probably fulfilling the need for a functional hearing screening test and has enhanced public awareness about hearing loss.

Measuring cognitive factors in speech comprehension: The value of using the Text Reception Threshold test as a visual equivalent of the SRT test

The ability to comprehend speech in noise is influenced by bottom-up auditory and top-down cognitive capacities. Separate examination of these capacities is relevant for various purposes. Speech-Reception-Threshold (SRT) tests measure an individuals ability to comprehend speech. This paper addresses the value of the Text-Reception-Threshold (TRT) test (a visual parallel of the SRT test) to assess the cognitive capacities allocated during speech comprehension. We conducted a secondary data analysis, including 87 normally-hearing adults (aged 18 to 78 years). Correlation coefficients between age, TRT, working memory (Spatial Span) and SRT were examined. The TRT and SRT correlated significantly (r = 0.30), supporting the value of TRT in explaining inter-individual differences in SRTs. The relations between age and TRT and between SSP and TRT were non-significant. The results indicate that the current TRT test does not fully cover the cognitive aspects relevant in speech comprehension. Adaptation of the test is required before clinical implementation can be considered.

HearCom: Hearing in the communication society

A group of 28 research partners joined the EU-funded project HearCom with the overall aim to improve hearing communication. One of the main achievements has been the provision of advanced hearing screening tests by telephone and Internet. Next to that it was aimed to harmonize hearing diagnostic tests for European languages. For this the concept of an Auditory Profile was defined on which a number of diagnostic hearing tests were developed in several languages. As hearing problems are also a result of adverse acoustical circumstances such as for room acoustics and telecom systems, these effects have been studied, modelled and evaluated for hearing impaired persons. In the area of rehabilitation a large scale comparison study was performed on signal enhancement techniques for hearing devices. Both objective and subjective benefits were found for specific listening conditions in relation to a chosen signal processing method. As modern technology may assist on hearing and communication it was studied how the use of automatic speech transcription or the use of handheld communication devices may help people with hearing problems. It is shown that communication benefits can be obtained, but that the benefit is limited in practice as processing power of todays handheld devices is still insufficient. An overview is given on the HearCom portal with sections for screening diagnostics, hearing information for the public and professionals, and a new HearCompanion service that provides step-by-step support for the hearing rehabilitation process.

Recognition of digits in different types of noise by normal-hearing and hearing-impaired listeners

The objective of the study was to examine the ability to understand digits in different types of noise. Adaptive speech-in-noise tests were developed that measure the speech-reception-threshold (SRTn) i.e. signal-to-noise ratio that corresponds to 50% intelligibility. Digits were presented in continuous noise, 16-Hz interrupted noise, and 32-Hz interrupted noise. Also the standard Dutch triplet SRTn test in continuous noise was included. Results for forty-two ears of normal-hearing and hearing-impaired adult participants are presented. The ratio between the standard deviation in SRTn values between subjects and the measurement error determines the efficiency of the tests. A high efficiency could be achieved by using triplets instead of digits, or by using 16-Hz interrupted noise instead of continuous noise, because this resulted in a large spread in SRTn values. The simple calculation method of averaging presentation levels was highly efficient. The digit SRTn test in 16-Hz interrupted noise was very efficient in discriminating between normal-hearing listeners and hearing-impaired listeners, and might be used to screen for hearing loss as measured by pure-tone audiometry.

Evaluation of the preliminary auditory profile test battery in an international multi-centre study

Abstract Objective: This paper describes the composition and international multi-centre evaluation of a battery of tests termed the preliminary auditory profile. It includes measures of loudness perception, listening effort, speech perception, spectral and temporal resolution, spatial hearing, self-reported disability and handicap, and cognition. Clinical applicability and comparability across different centres are investigated. Design: Headphone tests were conducted in five centres divided over four countries. Effects of test-retest, ear, and centre were investigated. Results for normally-hearing (NH) and hearing-impaired (HI) listeners are presented. Study sample: Thirty NH listeners aged 19–39 years, and 72 HI listeners aged 22–91 years with a broad range of hearing losses were included. Results: Test-retest reliability was generally good and there were very few right/left ear effects. Results of all tests were comparable across centres for NH listeners after baseline correction to account for necessary differences between test materials. For HI listeners, results were comparable across centres for the language-independent tests. Conclusions: The auditory profile forms a clinical test battery that is applicable in four different languages. Even after baseline correction, differences between test materials have to be taken into account when interpreting results of language-dependent tests in HI listeners.

The Influence of Masker Type on the Binaural Intelligibility Level Difference

The Binaural Intelligibility Level Difference (BILD) was first described by Licklider (1948). It is a manifestation of binaural unmasking, the advantage of binaural over monaural hearing of a signal S against the background of a spatially separated noise N. In headphone experiments, often a design with a N0S0 presentation vs a N0Sπ presentation is used, in which the noise is presented homophasic and the signal either homophasic or antiphasic. The BILD is then defined as the difference in the speech reception threshold (SRT) in the N0S0 and N0Sπ presentation mode. Blauert (1997) provides an overview of experimental work on BMLD and BILD. Estimating the BILD requires SRT measurements in the N0S0 and N0Sπ presentation modes. Since the diotic N0S0 stimuli contain no binaural information, they can be considered as an estimation of monaural speech perception (Siegel and Colburn 1983). The BILD for a stationary masker is known to be about 4–7 dB (e.g. Blauert 1997; Johansson and Arlinger 2002). We are interested in the BILD for fluctuating maskers because of their relevance for daily life. Assessing speech intelligibility in the presence of a fluctuating masker in a N0Sπ condition, several components should be taken into account (see Fig. 1): point of departure is the diotic speech reception threshold (SRT) for stationary noise (Fig. 1a.). If temporal modulations are introduced there will be release of masking (masking release, MR), the SRT reduces (Fig. 1b.). A typical value is of this masking release is 10 dB. On the other hand, if an interaural phase shift is introduced in the speech-signal the SRT will be reduced because of binaural unmasking (Fig. 1c.). A typical value of this binaural unmasking is 5 dB. The question addressed is this chapter is whether there is an interaction between the diotic (“monaural”) release of masking and the binaural unmasking. So, can the reduction in SRT in the condition with modulated noise and interaural phase shifted speech be predicted by adding the values of masking release and binaural unmasking, i.e. 10 + 5 = 15 dB or is it different?

Relations between psychophysical measures of spatial hearing and self-reported spatial-hearing abilities.

Abstract Objective: The aim of the present study was to investigate how well the virtual psychophysical measures of spatial hearing from the preliminary auditory profile predict self-reported spatial-hearing abilities. Design: Virtual spatial-hearings tests (conducted unaided, via headphones) and a questionnaire were administered in five centres in Germany, the Netherlands, Sweden, and the UK. Correlations and stepwise linear regression models were calculated among a group of hearing-impaired listeners. Study sample: Thirty normal-hearing listeners aged 19–39 years, and 72 hearing-impaired listeners aged 22–91 years with a broad range of hearing losses, including asymmetrical and mixed hearing losses. Results: Several significant correlations (between 0.24 and 0.54) were found between results of virtual psychophysical spatial-hearing tests and self-reported localization abilities. Stepwise linear regression analyses showed that the minimum audible angle (MAA) test was a significant predictor for self-reported localization abilities (5% extra explained variance), and the spatial speech reception threshold (SRT) benefit test for self-reported listening to speech in spatial situations (6% extra explained variance). Conclusions: The MAA test and spatial SRT benefit test are indicative measures of everyday binaural functioning. The binaural SRT benefit test was not found to predict self-reported spatial-hearing abilities.