Selecting Scenarios for Hearing-Related Laboratory Testing.

For hearing aid users to experience everyday benefit from their hearing aids, research, development, and fitting of hearing aids must be performed using evaluation methods that are indicative of everyday performance. These evaluations can take place both in peoples' ordinary lives and in laboratory settings. For the results of laboratory testing to be ecologically valid, the selected test scenarios must capture the essence of everyday listening. The present article discusses the selection of these laboratory test scenarios in three parts. Part 1 reviews prior research on the selection of everyday listening situations for laboratory testing and discusses realistic test scenarios as important research tools. Part 2 presents findings from an ecological momentary assessments study in which 19 experienced hearing aid users reported real-time auditory reality data, including their current listening activity and their current sound environment. Participants categorized their listening situations according to the common sound scenarios framework and rated how often each situation occurred, how important it was to hear well, and how difficult it was to hear in the situation. These ratings made it possible to filter the data according to three criteria (occurrence, importance, and difficulty). The filtered data could potentially be used for selecting laboratory test scenarios. Part 3 uses the data from Part 2 and data from the studies reviewed in Part 1 to broadly explore the test scenarios that various selection criteria lead to. Further, implementation of test scenarios in the laboratory, and the strengths and limitations of data collection methods for investigating auditory reality are briefly discussed. The article concludes with a summary of the collected study.

Bayesian analysis of paired-comparison sound quality ratings.

This paper presents a method to analyze paired-comparison data including either binary or graded ordinal responses, with or without ties. The proposed method can use either of two classical choice models: (1) Thurstone case V, which assumes a Gaussian distribution of the sensory variables underlying listener decisions, or (2) the Bradley-Terry-Luce (BTL) model, which assumes a logistic distribution. The analysis method was validated using simulated paired-comparison experiments with known distributions of the sound-quality parameters in the simulated population from which "participants" were generated at random. The validation indicated that the Thurstone and BTL models give similar results close to the true values. The estimated credibility of a quality difference was slightly higher with the BTL model. The analysis results showed dramatically better precision when the response data included graded ordinal judgments instead of binary responses. Allowing tied responses also tended to improve precision. The method was also applied to data from a real evaluation of hearing-aid programs. The analysis revealed clinically interesting results with high statistical credibility, although the amount of test data was limited.

Central auditory function in early Alzheimer's disease and in mild cognitive impairment.

OBJECTIVE: to investigate auditory function in subjects with early Alzheimer's disease, mild cognitive impairment and with subjective memory complaints, in search of signs of central auditory processing dysfunction even in early stages of cognitive impairment. DESIGN AND SUBJECTS: a consecutive group of men and women, referred to the Memory Clinic at the Karolinska University Hospital, was approached for inclusion in this prospective study. One hundred and thirty-six subjects, mean age 64 years (range 50-78 years), diagnosed with Alzheimer's disease (n = 43), mild cognitive impairment (n = 59) or with subjective memory complaints (n = 34), were included. METHODS: auditory function was assessed with pure tone audiometry, speech perception in quiet and in background noise and dichotic digits tests with two or three digits. RESULTS: pure tone audiometry and speech perception scores in quiet and in background noise were normal for age and without between-group differences. Dichotic digits tests showed strongly significant differences between the three groups, where the Alzheimer's disease group performed significantly poorer than the other two groups, with the mild cognitive impairment group in an intermediate position. CONCLUSIONS: our results demonstrate that central auditory processing dysfunction is highly evident in subjects with Alzheimer's disease, and to a considerable extent even in subjects with mild cognitive impairment.

Live Evaluation of Auditory Preference, a Laboratory Test for Evaluating Auditory Preference.

BACKGROUND: Many laboratory tests are performed under unrealistic conditions. Tasks, such as repeating words or sentences, are performed in simple loudspeaker setups. Currently, many research groups focus on realistic audiovisual laboratory setups. Fewer groups focus on the tasks performed during testing. PURPOSE: A semicontrolled laboratory test method focusing on the tasks performed, the Live Evaluation of Auditory Preference (LEAP) was evaluated. LEAP is developed to evaluate hearing-instrument performance in test scenarios that represent everyday listening situations. RESEARCH DESIGN: LEAP was evaluated in a feasibility study. The method comprises conversations between a test participant and one or two test leaders, enabling evaluation of the test participant's own voice. The method allows for visual cues (when relevant) and introduce social pressure to participate in the conversation. In addition, other everyday listening tasks, such as watching television (TV) and listening to radio, are included. In this study, LEAP was used to assess preference for two hearing aid settings using paired comparisons. STUDY SAMPLE: Nineteen experienced hearing aid users (13 females and 6 males; mean age 74 years), participated in the study. DATA COLLECTION AND ANALYSIS: LEAP was performed at three visits to the laboratory. In addition, participants conducted a field trial where the two hearing aid programs were compared using Ecological Momentary Assessments (EMA). During LEAP testing, six mandatory test cases were used, representing commonly occurring everyday listening situations. Individual test cases were also included, selected from individually experienced listening situations during the field trial. Within- and between-session reliability of the LEAP test was investigated. Validity was investigated by comparing the LEAP and the EMA results. RESULTS: For the current signal-processing evaluation, the test was judged to have acceptable reliability and validity. The inclusion of individually selected test cases increased the representativeness of the LEAP test, but it did not substantially alter the results in the current study. CONCLUSION: LEAP in its current implementation seems suitable for investigating signal-processing preference in the laboratory in a way that is indicative of everyday preference. The LEAP method represents one step forward in bringing the real world into the laboratory.

Short-term longitudinal study of central auditory function in Alzheimer's disease and mild cognitive impairment.

BACKGROUND/AIMS: Central auditory function can be studied to monitor the progression of mild cognitive impairment to dementia. Our aim was to address this issue in a prospective longitudinal setting. METHODS: Tests of central hearing function were performed on 70 subjects with either Alzheimer's disease (AD) or mild cognitive impairment, and in controls with subjective memory complaints but normal cognition. The time span until follow-up was 1.5 years. RESULTS: The dichotic digit free recall test showed a significant decline in the AD group compared with the controls (left ear). CONCLUSION: The short time span was long enough to disclose a central auditory processing decline in AD.

Standard audiograms for the IEC 60118-15 measurement procedure.

For the characterization of hearing aids, a new test method has been defined in the new International Electrotechnical Commission (IEC) standard 60118-15. For this characterization, the hearing aid will be set to actual user settings as programmed by standard fitting software from the hearing aid manufacturer. To limit the variation of programming outcomes, 10 standard audiograms, which cover the entire range of audiograms met in clinical practice, have been defined. This article describes how the set of standard audiograms has been developed. This set of standard audiogram has been derived by a vector quantization analysis method on a database of 28,244 audiograms. Using this analysis method, sets of typical audiograms have been obtained of sizes 12 and 60. It turned out that the smaller set could not be used for selecting audiograms as sloping audiograms were absent. Therefore, the larger set has been analyzed to provide seven standard audiograms for flat and moderately sloping hearing loss and three standard audiograms for steep hearing loss.

Methodology for quantifying perceptual effects from noise suppression systems.

Methodology is proposed for perceptual assessment of both subjective sound quality and speech recognition in such way that results can be compared between these two aspects. Validation is performed with a noise suppression system applied to hearing instruments. A method termed Interpolated Paired Comparison Rating (IPCR) was developed for time efficient assessment of subjective impression of different aspects of sound quality for a variety of noise conditions. The method is based on paired comparisons between processed and unprocessed stimuli, and the results are expressed as the difference in signal-to-noise ratio (dB) between these that give equal subjective impression. For tests of speech recognition in noise, validated adaptive test methods can be used that give results in terms of speech-to-noise ratio. The methodology was shown to be sensitive enough to detect significant mean differences between processed and unprocessed speech in noise, both regarding subjective sound quality and speech recognition ability in groups consisting of 30 subjects. An effect on sound quality from the noise suppression equivalent to about 3-4 dB is required to be statistically significant for a single subject. A corresponding effect of 3-6 dB is required for speech recognition (one-sided test). The magnitude of difference that occurred in the present study for sound quality was sufficient to show significant differences for sound quality within individuals, but this was not the case for speech recognition.