Stig Arlinger

An international comparison of long‐term average speech spectra

The long‐term average speech spectrum (LTASS) and some dynamic characteristics of speech were determined for 12 languages: English (several dialects), Swedish, Danish, German, French (Canadian), Japanese, Cantonese, Mandarin, Russian, Welsh, Singhalese, and Vietnamese. The LTASS only was also measured for Arabic. Speech samples (18) were recorded, using standardized equipment and procedures, in 15 localities for (usually) ten male and ten female talkers. All analyses were conducted at the National Acoustic Laboratories, Sydney. The LTASS was similar for all languages although there were many statistically significant differences. Such differences were small and not always consistent for male and female samples of the same language. For one‐third octave bands of speech, the maximum short‐term rms level was 10 dB above the maximum long‐term rms level, consistent across languages and frequency. A ‘‘universal’’ LTASS is suggested as being applicable, across languages, for many purposes including use in hearing aid prescription procedures and in the Articulation Index.

Negative consequences of uncorrected hearing loss—a review

Hearing loss gives rise to a number of disabilities. Problems in recognizing speech, especially in difficult environments, give rise to the largest number of complaints. Other kinds of disabilities may concern the reduced ability to detect, identify and localize sounds quickly and reliably. Such sounds may be warning or alarm signals, as well as music and birds singing. The communicative disability affects both hearing-impaired people and other people in their environment—family members, fellow workers, etc. Hearing-impaired people arc not always aware of all the consequences of the impairment; they do not always know what they are missing. Several studies have shown that uncorrected hearing loss gives rise to poorer quality of life, related to isolation, reduced social activity, and a feeling of being excluded, leading to an increased prevalence of symptoms of depression. These findings indicate the importance of early identification of hearing loss and offers of rehabilitative support, where the fitting of hearing aids is usually an important component. Several studies also point to a significant correlation between hearing loss and loss of cognitive functions. Most of these studies show such a correlation without being able to show whether the hearing loss caused the reduction in cognitive performance or if both the hearing loss and the cognitive decline are parts of a common, general age-related degeneration. A couple of these studies, however, indicate that the uncorrected hearing loss may be the cause of cognitive decline. Whichever alternative is true, the correlation should be seen as a clear indication for early hearing aid fitting for those needing it. Monaural hearing aid fitting in subjects with bilateral hearing loss may give rise to a reduced ability to recognize speech presented to the unaided ear, the so-called late-onset auditory deprivation effect. This functional decline is reversible in some but not all subjects after fitting of a hearing aid also on the previously unaided ear.

Optimal Outcome Measures, Research Priorities, and International Cooperation

&NA; The participants in the Eriksholm Workshop on “Measuring Outcomes in Audiological Rehabilitation Using Hearing Aids” debated three issues that are reported in this article. First, it was agreed that the characteristics of an optimal outcome measure vary as a function of the purpose of the measurement. Potential characteristics of outcome self‐report tools for four common goals of outcome measurement are briefly presented to illustrate this point. Second, 10 important research priorities in outcome measurement were identified and ranked. They are presented with brief discussion of the top five. Third, the concept of generating a brief universally applicable outcome measure was endorsed. This brief data set is intended to supplement existing outcome measures and to promote data combination and comparison across different social, cultural, and health‐care delivery systems. A set of seven core items is proposed for further study.

Masking of speech by amplitude‐modulated noise

The masking of speech by amplitude-modulated and unmodulated speech-spectrum noise has been evaluated by the measurement of monaural speech recognition in such noise on young and elderly subjects with normal-hearing and elderly hearing-impaired subjects with and without a hearing aid. Sinusoidal modulation with frequencies covering the range 2-100 Hz, as well as an irregular modulation generated by the sum of four sinusoids in random phase relation, was used. Modulation degrees were 100%, +/- 6 dB, and +/- 12 dB. Root mean-square sound pressure level was equal for modulated and unmodulated maskers. For the normal-hearing subjects, essentially all types of modulated noise provided some release of speech masking as compared to unmodulated noise. Sinusoidal modulation provided more release of masking than the irregular modulation. The release of masking increased with modulation depth. It is proposed that the number and duration of low-level intervals are essential factors for the degree of masking. The release of masking was found to reach a maximum at a modulation frequency between 10 and 20 Hz for sinusoidal modulation. For elderly hearing-impaired subjects, the release of masking obtained from amplitude modulation was consistently smaller than in the normal-hearing groups, presumably related to changes in auditory temporal resolution caused by the hearing loss. The average speech-to-noise ratio required for 30% correct speech recognition varied greatly between the groups: For young normal-hearing subjects it was -15 dB, for elderly normal-hearing it was -9 dB, for elderly hearing-impaired subjects in the unaided listening condition it was +2 dB and in the aided condition it was +3 dB. The results support the conclusion that within the methodological context of the study, age as well as sensorineural hearing loss, as such, influence speech recognition in noise more than what can be explained by the loss of audibility, according to the audiogram and the masking noise spectrum.

The emergence of Cognitive Hearing Science

Cognitive Hearing Science or Auditory Cognitive Science is an emerging field of interdisciplinary research concerning the interactions between hearing and cognition. It follows a trend over the last half century for interdisciplinary fields to develop, beginning with Neuroscience, then Cognitive Science, then Cognitive Neuroscience, and then Cognitive Vision Science. A common theme is that an interdisciplinary approach is necessary to understand complex human behaviors, to develop technologies incorporating knowledge of these behaviors, and to find solutions for individuals with impairments that undermine typical behaviors. Accordingly, researchers in traditional academic disciplines, such as Psychology, Physiology, Linguistics, Philosophy, Anthropology, and Sociology benefit from collaborations with each other, and with researchers in Computer Science and Engineering working on the design of technologies, and with health professionals working with individuals who have impairments. The factors that triggered the emergence of Cognitive Hearing Science include the maturation of the component disciplines of Hearing Science and Cognitive Science, new opportunities to use complex digital signal-processing to design technologies suited to performance in challenging everyday environments, and increasing social imperatives to help people whose communication problems span hearing and cognition. Cognitive Hearing Science is illustrated in research on three general topics: (1) language processing in challenging listening conditions; (2) use of auditory communication technologies or the visual modality to boost performance; (3) changes in performance with development, aging, and rehabilitative training. Future directions for modeling and the translation of research into practice are suggested.

A Swedish version of the Hearing In Noise Test (HINT) for measurement of speech recognition

A Swedish Hearing In Noise Test (HINT), consisting of everyday sentences to be used in an adaptive procedure to estimate the speech recognition thresholds in noise and quiet, has been developed. The material consists of 250 sentences, with a length of five to nine syllables, normalized for naturalness, difficulty and reliability. The sentences were recorded with a female speaker. From the sentences, 25 phonemically balanced lists were created. All lists fluctuate less than 1 dB of the overall mean. The standard deviation of the test-retest difference is 0.94 dB when testing with one list, and decreases to 0.68 dB and 0.56 dB for two and three lists, respectively. The average speech recognition thresholds in noise for the Swedish sentences were −3.0 dB signal/noise ratio (SD = 1.1 dB). The present study has resulted in a well-defined and internationally comparable set of sentences, which can be used in Swedish audiological rehabilitation and research to measure speech recognition in noise and quiet.

Idiopathic sudden sensorineural hearing loss: results drawn from the Swedish national database

Conclusion. The first results from 300 patients in a Swedish national database for sudden sensorineural hearing loss (SSNHL) demonstrate that corticosteroids or ‘no treatment at all’ are the treatment options in use today. No significant difference in outcome was seen between treated and non-treated patients. Since spontaneous recovery might be the cause, a placebo-controlled randomized study is required before a positive effect of corticosteroids can be asserted. Objectives. To investigate the treatment policy for SSNHL in Sweden, the effect on outcome, and which variables are of value in predicting the outcome. Patients and methods. A national database was developed in Sweden which gathers data from patients with SSNHL. A form is used for data collection covering background, current disease, examinations, and treatment. Audiograms at the onset of SSNHL and after 3 months are analyzed. Results. Of 300 patients, 208 were considered to have idiopathic SSNHL; 50% were treated with corticosteroids, 44% did not receive any treatment. The treated patients had the same outcome as the non-treated patients. The time interval from onset of SSNHL to start of treatment was of importance for the outcome irrespective of type of audiogram or results from laboratory tests. Higher age and heredity for hearing loss gave a significantly lower chance of improvement.

Cognitive effects in dichotic speech testing in elderly persons

Objective To study the effect of chronologic age on central auditory functions using dichotic speech tests and to study whether and how the age effect in dichotic listening is related to cognitive ability. Design Dichotic speech tests and cognitive tests were performed on 30 bilaterally hearing-impaired subjects, with a pure-tone average better than 50 dB HL. They were between 42 and 84 yr of age and were divided into an older and a younger group comprising 15 subjects each. The dichotic test material were digits, low-redundancy sentences and consonant-vowel syllables. The subjects reported stimuli heard in both ears (free report) or in one ear (directed report to left or right ear). The cognitive test battery comprised tests focusing on short-term memory, verbal information-processing speed and phonologic processing. Results A decreased overall performance in all dichotic speech tests was observed in the older group. In the syllable test the older subjects showed poorer results when focusing on the stimuli heard in the left ear, as compared with when focusing on stimuli heard in the right ear, whereas the younger group showed almost equal results for left- and right ear-focusing conditions. An age effect was also seen in reaction times recorded in the cognitive tests and in the scores of the reading span test. These cognitive parameters correlate with the results of the dichotic test when focusing to the left, but not when focusing to the right in the directed report condition. In the free report condition the overall performance showed a high correlation with cognitive test parameters. Conclusions Effects of chronologic age in dichotic speech tests in the elderly have been verified. The degree of effect is dependent on test material, way of reporting and focusing condition. The different listening tasks in dichotic tests put different demands on cognitive ability shown by a varying degree of correlations between cognitive function and dichotic test parameters. Also, the results indicate a strong connection between age-related cognitive decline in the elderly and problems to perceive stimuli presented to the left ear.

Audiological and Vestibulo-Oculomotor Findings in Workers Exposed to Solvents and Jet Fuel

Three groups of subjects with long-term (5-41 years) occupational exposure to industrial solvents have been evaluated with extensive audiological and vestibular test batteries. Group A comprised 16 subjects with a confirmed diagnosis of psycho-organic syndrome (POS), while group B consisted of 7 subjects with suspected POS. Both groups had been exposed to mixtures of aliphatic and aromatic solvents. Eight subjects with long-term exposure to jet fuel constituted group C. In the audiological test battery, discrimination of interrupted speech and evoked cortical potentials in response to frequency glides were the tests that yielded significantly abnormal results. In the vestibular test battery, considerable pathology was seen in electronystagmography, and in addition, visual suppression test and saccade test indicated CNS disturbance. In general, when a test yielded pathological results, the incidence of pathology was highest in group A and lowest in group C.

Speech understanding in quiet and noise, with and without hearing aids

Speech recognition and cognitive functions important for speech understanding were evaluated by objective measures and by scores of perceived effort, with and without hearing aids. The tests were performed in silence, and with background conditions of speech spectrum random noise and ordinary speech. One young and one elderly group of twelve hearing-impaired subjects each participated. Hearing aid use improved speech recognition in silence (7 dB) and in the condition with speech as background (2.5 dB S/N), but did not change the perceived effort scores. In the cognitive tests no hearing aid benefit was seen in objective measures, while there was an effect of hearing aid use in scores of perceived effort, subjects reported less effort. There were no age effects on hearing aid benefit. In conclusion, hearing aid use may result in reduced effort in listening tasks that is not associated with improvement in objective scores.