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

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.

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 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.

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.