Chantal Laroche

Adaptation of the HINT (hearing in noise test) for adult Canadian Francophone populations

The HINT provides an efficient and reliable method of assessing speech intelligibility in quiet and in noise by using an adaptive strategy to measure speech reception thresholds for sentences, thus avoiding ceiling and floor effects that plague traditional measures performed at fixed presentation levels. A strong need for such a test within the Canadian Francophone population, led us to develop a French version of the HINT. Here we describe the development of this test. The Canadian French version is composed of 240-recorded sentences, equated for intelligibility, and cast into 12 phonemically balanced 20-sentence lists. Average headphone SRTs, measured with 36 adult Canadian Francophone native speakers with normal hearing, were 16.4 dBA in quiet, −3.0 dBA SNR in a 65 dBA noise front condition and −11.4 dBA SNR in a 65 dBA noise side condition. Reliability was established by means of within-subjects standard deviation of repeated SRT measurements over different lists and yielded values of 2.2 and 1.1 dB for the quiet and noise conditions, respectively.

Work integration issues go beyond the nature of the communication disorder

UNLABELLED The ability to obtain and maintain employment is one of societys most valued life participation events and is often considered in measurements of quality of life (QOL). Many workplaces now require good communication skills and this may jeopardize the opportunity for persons with communication disorders (CD) to access interesting jobs. Sarno, Silverman, and Levita (1970) have long emphasized that functioning is a result of the interaction of psychosocial factors as well as communication disorder characteristics. The current study gathered perceptions from different groups of persons with CD, from service providers and employers on the barriers to work integration. The results show that many barriers are common across types of CD. Such examples are noise, tasks requiring speed, having to speak to groups of persons and the attitudes of others. Although some common barriers were identified between the service providers and the persons with CD, service providers placed more emphasis on psychological adaptation aspects than did persons with CD. Employers generated an equivalently long list of barriers but were also very concerned about job market issues. LEARNING OUTCOMES As a result of this activity, the following learning outcomes will be realized: participants will be able to (1) identify barriers that service providers and persons with CD each perceive; (2) identify differences in the perceptions of each group concerning barriers; (3) learn ways to modify or eliminate barriers that interfere with successful employment among individuals with CD.

Perceptions of the obstacles to work reintegration for persons with aphasia

The Handicap Creation Process Model (HCPM) suggests that persons with disabilities may experience difficulties at work because of environmental barriers. The present study reports on the perceptions of persons with aphasia, of speech-language pathologists and of employers regarding the potential barriers to job (re)integration. Statements were gathered using a focus group and a nominal group technique, and analysed according to whether the barriers were perceived as residing with the individual, with the organization or with society. Qualitative differences were noted among the perceptions of the three groups. Speech-language pathologists focused on the personal and societal barriers where employers focused on the organizational barriers. Persons with aphasia perceived barriers at all levels. Suggestions for strategies for eliminating these barriers for persons with communication disorders were also collected.

Establishment of age-specific normative data for the canadian French version of the hearing in noise test for children.

Objectives: A Canadian French version of the Hearing in Noise Test (HINT) has been developed to assess children’s ability to recognize speech in noise. To avoid testing a large number of children in each clinical test site to establish soundfield norms, a protocol based on the use of correction factors has been proposed and validated in the current study. More specifically, the objective of this study was to provide a protocol for the establishment of age-specific normative data for the Canadian French HINT for children to facilitate its clinical use and allow comparing an individual child’s performance with that of age-matched normal hearing children. Using the proposed protocol, a limited number of normal hearing adults are tested in each HINT condition to correct the adult headphone norms for the soundfield in question, and the correction factors established in the current study are then applied to generate age-specific soundfield norms. Mean adult performance values obtained in a given soundfield are entered into the HINT software, which automatically derives the soundfield adult norms, age-specific children norms, and percentile rankings. Design: Speech reception thresholds (SRT) for sentences were measured in 70 native French-speaking subjects to establish mean performances across various age groups, and correction factors were calculated by comparing performance in each age group with adult performance. To validate the normalization protocol, 28 additional subjects were tested in a new soundfield. The correction factors were applied to adult performance (N = 15) and the resulting predicted scores were compared with measured performance in a group of 9-yr olds (N = 13). Results: Statistical analyses indicate that SRTs decrease with age and reach adult values in older children (12-yr olds). Correction factors are therefore provided for children 6 to 12 yrs old. Spatial separation advantage, the improvement in SRT when speech and noise are spatially separated, also improves with age. The correction factors were effective in predicting mean SRTs for a previously untested age group in all HINT conditions apart from the quiet condition. The difference between predicted and measured performances was less than 0.5 dB for the noise conditions but exceeded 4 dB in the quiet condition. The reliability of SRT measures was determined, with an overall within-subjects SD of repeated measurements of 0.7 dB for the noise front condition. No learning effect was found in the current data. Conclusions: Correction factors can be used to predict performance on the HINT in a group of normal-hearing children in all HINT conditions, apart from quiet. Findings of the current study concur with the literature on age effects in auditory processing abilities, where performance on a variety of auditory tasks has been demonstrated to increase with age to reach adult-like values in adolescence or past 10 yrs.

Audibility Problems with Fire Alarms in Apartment Buildings

A previous study of apartment building evacuation drills showed that as many as 25% of the occupants mentioned not hearing the fire alarm from inside their apartments. A new experiment was developed to observe evacuation drills and to measure the sound level of the fire alarms in three high-rise apartment buildings. These buildings, built during the 1980s, met the local building regulations regarding the provision of fire alarms at the time of construction. Each building contained approximately 200 apartments, with 1 to 4 persons per apartment. For each building, the printed fire safety procedures stated that all occupants should leave the building or move to an area of refuge, upon hearing the building fire alarm. During each evacuation drill, video cameras, were located in corridors and staircases, to record the movement time and behaviour of occupants. Using a digital audio tape recorder, precise sound samples of the fire alarm and background noise were taken from different locations in the buildings. Analyses of the alarm sound spectrum and levels were performed. Results confirm the subjective assessment of occupants who mentioned not hearing the fire alarm in specific locations of the building. It was also found that, in some other areas, the alarm was overpowering. The impact of alarm audibility on fire safety is discussed.

Comparison of sound propagation and perception of three types of backup alarms with regards to worker safety

A technology of backup alarms based on the use of a broadband signal has recently gained popularity in many countries. In this study, the performance of this broadband technology is compared to that of a conventional tonal alarm and a multi-tone alarm from a worker-safety standpoint. Field measurements of sound pressure level patterns behind heavy vehicles were performed in real work environments and psychoacoustic measurements (sound detection thresholds, equal loudness, perceived urgency and sound localization) were carried out in the laboratory with human subjects. Compared with the conventional tonal alarm, the broadband alarm generates a much more uniform sound field behind vehicles, is easier to localize in space and is judged slighter louder at representative alarm levels. Slight advantages were found with the tonal alarm for sound detection and for perceived urgency at low levels, but these benefits observed in laboratory conditions would not overcome the detrimental effects associated with the large and abrupt variations in sound pressure levels (up to 15-20 dB within short distances) observed in the field behind vehicles for this alarm, which are significantly higher than those obtained with the broadband alarm. Performance with the multi-tone alarm generally fell between that of the tonal and broadband alarms on most measures.

Functionally-based screening criteria for hearing-critical jobs based on the Hearing in Noise Test.

Effective communication is a crucial requirement in many workplaces to ensure safe and effective operations. Often, critical verbal communications are carried out in noise, which can be very challenging, particularly for individuals with hearing loss. Diagnostic measures of hearing, such as the audiogram, are not adequate to make accurate predictions of speech intelligibility in real-world environments for specific workers, and thus are not generally suitable as a basis for making employment decisions. Instead, the Hearing in Noise Test (HINT) has been identified and validated for use in predicting speech intelligibility in a wide range of communication environments. The approach to validation of the HINT takes into account the expected voice level of the talker, the communication distance between the talker and the listener, and a statistical model of speech intelligibility in real-world occupational noises. For each hearing-critical task, a HINT screening threshold score is derived upon specification of the minimum level of performance required of the workers. The HINT is available in several languages, so the tools developed are applicable in a wide range of settings, including multilingual workplaces.

The Canadian French Hearing in Noise Test

English and French represent the two official languages of Canada. During the last census, 23.2% of Canadians identified French as their mother tongue (Statistics Canada, 2001). Unfortunately, until recently, there were no reliable, standardized, and efficient tools for the assessment of sentence-length speech intelligibility in noisy listening conditions to serve this segment of the Canadian population. This report summarizes the development of a Canadian French version of the HINT. A more detailed description can be found in Vaillancourt et al (2005).

A Psychoacoustical Model for Specifying the Level and Spectrum of Acoustic Warning Signals in the Workplace

A psychoacoustic model is presented to facilitate the installation of acoustic warning devices in noisy settings, reflecting a major upgrade of a former tool, Detectsound. The model can be used to estimate the optimal level and spectrum of acoustic warning signals based on the noise field in the workplace, the hearing status of workers, and the attenuation provided by hearing protectors. The new version can be applied to a wider range of situations. Analyses can now be conducted to meet the functional requirements for a specific worker or to suit the needs for a group of co-workers sharing a work area. Computation of optimal warning signals can also be made from estimated hearing parameters based on the worker age, gender, and level and duration of noise exposure. The results of a laboratory validation study showed that the mean error in estimating detection thresholds for normal hearing individuals is typically within ±1 dB with a standard deviation of less than 2.5 dB in white noise or continuous noise fields. The model tends to yield slightly overestimated warning signal detection thresholds in fluctuating noises. Proper application of the tool also requires consideration of the variability in estimating noise levels, hearing status, and hearing protector attenuation under field conditions to ensure that acoustic warning signals are sufficiently loud and well adjusted in practice.

Determination of optimal acoustic features for reverse alarms: field measurements and the design of a sound propagation model

Reverse alarms available on the market present deficiencies with respect to their acoustic features and their placement on vehicles. It is therefore important to (1) better document sound propagation phenomena involving the backing up of heavy duty vehicles, (2) design software that can simulate the sound field generated by reverse alarms behind heavy duty vehicles, and, with this model, (3) determine the optimal acoustic and placement features. In order to meet these goals, four heavy duty vehicles (a grader, a loader, a cement mixer, and a dump truck) were each alternately equipped with five different reverse alarms. Audionumeric recordings were made on different axes behind the heavy duty vehicles. The recordings were studied with a software package allowing one to view the variation in sound pressure level as a function of the microphone placement. These field data allowed validation of a computerized model of sound propagation of reverse alarms (ALARME software), considering the phenomena of sound wa...