Word recognition within a linguistic context: effects of age, hearing acuity, verbal ability, and cognitive function.

OBJECTIVE: Participants in traditional studies of the effects of context on spoken word recognition have been university undergraduates. When older adults have been included, they have typically been matched with these young adults for verbal ability or years of education. Although this may be a good strategy for eliminating confounding variables, it is not clear how results of these studies may extend to the general population of young and older adults. The objective of this study was to examine the effects of adult age, hearing acuity, verbal ability, and cognitive function on the use of linguistic context in spoken word recognition. DESIGN: Fifty-three adults, aged 19 to 89 yr, heard short sentences in which the final word was masked by multitalker babble. The level of babble was progressively reduced in 2 dB steps until the sentence-final word could be correctly identified. Published norms were used to construct sets of sentences in which the same word could be heard with three levels of predictability (low, medium, and high) based on the linguistic context. In a fourth condition (no context), the words were preceded by a neutral carrier phrase. Participants received tests of verbal ability, with an emphasis on vocabulary knowledge, a brief test battery to assess cognitive function, and an assessment of hearing acuity based on pure-tone thresholds. Participants' hearing acuity ranged from normal acuity to moderate hearing loss. RESULTS: Results showed that the signal to noise ratio necessary for correct word recognition varied inversely with the probability of that word occurring in the sentence context. Hearing loss had a significant effect on word recognition for words heard in a neutral context, but the effect of hearing acuity diminished progressively with increasing contextual probability of the target word. Hierarchical multiple regressions showed that hearing acuity accounted for a significant amount of the variance at the lowest three levels of contextual probability but not at the highest probability level tested. Cognitive function contributed significantly to the obtained variance in word recognition performance at all levels of contextual probability tested. Moreover, participant age accounted for a significant amount of variance even after hearing acuity and cognitive function were taken into account. Verbal ability in the range represented by the test participants did not contribute significantly to recognition performance in any of the context conditions. CONCLUSIONS: Peripheral hearing acuity accounted for only a part of the variance in word recognition accuracy, with significant variance also contributed by individual differences in cognitive function and participant age. Results showed the ability to use linguistic context to aid spoken word recognition is sufficiently robust that a relatively wide range in verbal ability among native English speakers had no effect on recognition performance.

The role of vestibular rehabilitation in the balance disorder patient.

The focus of this article is on the role of vestibular rehabilitation in the remediation of postural and gaze instability in individuals with peripheral vestibular deficits. Although vestibular rehabilitation does not cure the organic disease that produces the balance disorder, it improves mobility, prevents falls, and overall has a positive impact on the quality of life for the patient.

Monotic auditory processing disorder tests in the older adult population.

The purpose of this study was to determine if peripheral hearing loss of varying degrees in elderly subjects affected performance on monotic auditory processing disorder (APD) tests. A battery of monotic APD tests was administered to a group of well-educated and high-functioning older adults who were divided into three subgroups based on hearing acuity but similar in age: (1) normal hearing out to 4000 Hz with a slight high-frequency slope above that point, (2) normal hearing in the speech range but greater high-frequency loss (sloping configuration), and (3) hearing loss in both the low and high frequencies (low/high). The findings documented that subjects with normal hearing in the speech range performed well on all the APD tests. The subjects in the two hearing loss groups, however, performed more poorly on certain tests. The low/high loss subjects did significantly poorer than did the sloping subjects. These data suggest that low/high-frequency peripheral hearing loss is a factor for poor performance on certain monotic APD tests. Results further showed that when cognitive ability and presentation level are held constant, chronological age does not appear to be a contributing factor to performance on the majority of these monotic APD tests. If APD tests are to be administered to elder subjects, peripheral hearing loss configuration needs to be documented. For subjects with low/high-frequency losses, the tester needs to be aware that serious contamination of the results may occur.

Effects of adult aging and hearing loss on comprehension of rapid speech varying in syntactic complexity.

Comprehension of spoken language by older adults depends not only on effects of hearing acuity and age-related cognitive change but also on characteristics of the message, such as syntactic complexity and presentation rate. When younger and older adults with clinically normal hearing and with mild-to-moderate hearing loss were tested on comprehension of short spoken sentences that varied in syntactic complexity, minimal effects of age and hearing were seen in comprehension of syntactically simpler sentences, even at rapid speech rates. By contrast, both age and hearing loss were associated with poorer comprehension for more syntactically complex sentences, and these differences were further exacerbated by increases in speech rate. These findings illustrate a dynamic interaction between age, hearing acuity, and characteristics of the spoken message on speech comprehension.

Vestibular evoked myogenic potentials: history and overview.

Vestibular evoked myogenic potential (VEMP) testing is a relatively new diagnostic tool that is in the process of being investigated in patients with specific vestibular disorders. In this review, we will outline the history and provide a current review of VEMP research. Briefly, the VEMP is a biphasic response elicited by loud clicks or tone bursts recorded from the tonically contracted sternocleidomastoid muscle. Current data suggest that the VEMP is a vestibulo-collic reflex whose afferent limb arises from acoustically sensitive cells in the saccule, with signals conducted via the inferior vestibular nerve. We will review the history of the response and detail the anatomy and physiology associated with the test. We will discuss specific VEMP applications in the diagnosis of Meniere's disease, vestibular schwannoma, vestibular hypersensitivity disorders, vestibular neuritis, multiple sclerosis, and other brainstem lesions.

Boston University Doctor of Science Degree Program: clinical doctorate in audiology.

This article describes the development of the Boston University Clinical Doctoral Program in Audiology dating from its inception in 1985 to the present. The issues surrounding the establishment of the clinical doctorate, entering the program, and the curriculum are discussed. The unique features of this program and associated resources available within the clinical and scientific community of the greater Boston area are highlighted.

Hearing loss and perceptual effort: downstream effects on older adults' memory for speech.

A group of older adults with good hearing and a group with mild-to-moderate hearing loss were tested for recall of the final three words heard in a running memory task. Near perfect recall of the final words of the three-word sets by both good- and poor-hearing participants allowed the inference that all three words had been correctly identified. Nevertheless, the poor-hearing group recalled significantly fewer of the nonfinal words than did the better hearing group. This was true even though both groups were matched for age, education, and verbal ability. Results were taken as support for an effortfulness hypothesis: the notion that the extra effort that a hearing-impaired listener must expend to achieve perceptual success comes at the cost of processing resources that might otherwise be available for encoding the speech content in memory.

Output levels of commercially available portable compact disc players and the potential risk to hearing.

OBJECTIVE: To measure the sound levels generated by the headphones of commercially available portable compact disc players and provide hearing healthcare providers with safety guidelines based on a theoretical noise dose model. DESIGN: Using a Knowles Electronics Manikin for Acoustical Research and a personal computer, output levels across volume control settings were recorded from headphones driven by a standard signal (white noise) and compared with output levels from music samples of eight different genres. Many commercially available models from different manufacturers were investigated. Several different styles of headphones (insert, supra-aural, vertical, and circumaural) were used to determine if style of headphone influenced output level. RESULTS: Free-field equivalent sound pressure levels measured at maximum volume control setting ranged from 91 dBA to 121 dBA. Output levels varied across manufacturers and style of headphone, although generally the smaller the headphone, the higher the sound level for a given volume control setting. Specifically, in one manufacturer, insert earphones increased output level 7-9 dB, relative to the output from stock headphones included in the purchase of the CD player. In a few headphone-CD player combinations, peak sound pressure levels exceeded 130 dB SPL. CONCLUSIONS: Based on measured sound pressure levels across systems and the noise dose model recommended by National Institute for Occupational Safety and Health for protecting the occupational worker, a maximum permissible noise dose would typically be reached within 1 hr of listening with the volume control set to 70% of maximum gain using supra-aural headphones. Using headphones that resulted in boosting the output level (e.g., insert earphones used in this study) would significantly decrease the maximum safe volume control setting; this effect was unpredictable from one manufacturer to another. In the interest of providing a straightforward recommendation that should protect the hearing of the majority of consumers, reasonable guidelines would include a recommendation to limit headphone use to 1 hr or less per day if using supra-aural style headphones at a gain control setting of 60% of maximum.

Subjective hearing loss and history of traumatic brain injury exhibits abnormal brainstem auditory evoked response: a case report.

A 30-year-old woman presented with long-standing subjective unilateral auditory difficulties 13 years after sustaining closed head trauma. The battery of audiologic tests indicated normal hearing, but brainstem auditory evoked response (BAER) tests revealed abnormal neurogenic potentials in the symptomatic ear. The discrepancy between a normal pure tone audiogram and abnormal BAERs suggests that a site of neurologic injury could be causing the patient's problem with auditory perception. Imaging studies with gadolinium enhancement, however, did not document any abnormalities in the brainstem. Our present findings and previously published literature help identify the specific site of a neurologic deficit when routine audiologic tests and imaging studies detect no significant abnormality.