Linguistic Factors Influencing Speech Audiometric Assessment

Linguistic Complexity of Speech Recognition Test Sentences and Its Influence on Children's Verbal Repetition Accuracy

OBJECTIVES

Speech recognition (SR)-tests have been developed for children without considering the linguistic complexity of the sentences used. However, linguistic complexity is hypothesized to influence correct sentence repetition. The aim of this study is to identify lexical and grammatical parameters influencing verbal repetition accuracy of sentences derived from a Dutch SR-test when performed by 6-year-old typically developing children.

DESIGN

For this observational, cross-sectional study, 40 typically developing children aged 6 were recruited at four primary schools in the Netherlands. All children performed a sentence repetition task derived from an SR-test for adults. The sentence complexity was described beforehand with one lexical parameter, age of acquisition, and four grammatical parameters, specifically sentence length, prepositions, sentence structure, and verb inflection. A multiple logistic regression analysis was performed.

RESULTS

Sentences with a higher age of acquisition (odds ratio [OR] = 1.59) or greater sentence length (OR = 1.28) had a higher risk of repetition inaccuracy. Sentences including a spatial (OR = 1.25) or other preposition (OR = 1.25) were at increased risk for incorrect repetition, as were complex sentences (OR = 1.69) and sentences in the present perfect (OR = 1.44) or future tense (OR = 2.32).

CONCLUSIONS

The variation in verbal repetition accuracy in 6-year-old children is significantly influenced by both lexical and grammatical parameters. Linguistic complexity is an important factor to take into account when assessing speech intelligibility in children.

LiCoS: A New Linguistically Controlled Sentences Test to Assess Functional Hearing Performance

PURPOSE

To overcome the potential tension between clinical and ecological validity in speech audiometric assessment by creating a new set of sentence materials with high linguistic validity for the Dutch-speaking area.

METHODS

A linguistic "fingerprint" of modern spoken Dutch and Flemish served to generate a set of sentences recorded from 1 male and 1 female talker. The sentences were presented to 30 normal-hearing listeners in stationary speech noise at a signal-to-noise ratio (SNR) of -5 dB sound pressure level (SPL). A list design criterion was used to achieve perceptive homogeneity across the test lists, by scrambling lists of sentences of different syntactic types while controlling for linguistic complexity. The original set of test materials was narrowed down to 360 sentences, and list equivalency was evaluated at the audiological and linguistic levels. A psychometric curve was generated with a resolution of 2 dB based on a second group of 60 young normal-hearing native speakers of Dutch and Flemish.

RESULTS

Sentence understanding showed an average repetition accuracy of 63.40% (SD 1.01) across the lists at an SNR of -5 dB SPL. No significant differences were found between the lists at the level of the individual listener. At the linguistic level, the sentence lists showed an equal distribution of phonological, morphological, and syntactic features.

CONCLUSION

LiCoS combines the clinical benefit of acoustic control at the list level with the high ecological validity of linguistically representative test items. The new speech audiometric test is particularly appropriate to assess sentence understanding in individuals who would otherwise exhibit near-ceiling performance when tested with linguistically more simplified test stimuli. In combination with pure tone audiometric assessment, LiCoS provides valuable complementary information with respect to the functional hearing of patients.

Speech understanding in noise in elderly adults: the effect of inhibitory control and syntactic complexity

BACKGROUND

Previous research has suggested that speech perception in elderly adults is influenced not only by age-related hearing loss or presbycusis but also by declines in cognitive abilities, by background noise and by the syntactic complexity of the message.

AIMS

To gain further insight into the influence of these cognitive as well as acoustic and linguistic factors on speech perception in elderly adults by investigating inhibitory control as a listener characteristic and background noise type and syntactic complexity as input characteristics.

METHODS & PROCEDURES

Phoneme identification was measured in different noise conditions and in different linguistic contexts (single words, sentences with varying syntactic complexity). Additionally, inhibitory control was measured using a visual stimulus-response matching task. Fifty-one adults participated in this study, including elderly adults with age-related hearing loss (n = 9) and with normal hearing (n = 17), and a control group of normal hearing younger adults (n = 25).

OUTCOMES & RESULTS

The analysis revealed that elderly adults with normal hearing and with hearing loss were less likely to identify successfully phonemes in single words than younger normal hearing controls. In the context of sentences, only elderly adults with hearing loss had a lower odds of correct phoneme perception than the control group. Additionally, in elderly adults with hearing loss, phoneme-in-sentence perception was linked to age-related declines in inhibitory control. In all participants, phoneme identification in sentences was influenced by both noise type and syntactic complexity.

CONCLUSIONS & IMPLICATIONS

Inhibitory control and syntactic complexity might play a significant role in speech perception, especially in elderly listeners. These factors might also influence the results of clinical assessments of speech perception. Testing procedures thus need to be selected and their results interpreted carefully with these influences in mind.