Reference values for psychoacoustic tests on Polish school children 7-10 years old

Good hearing is a fundamental skill that allows children to develop properly, both socially and intellectually. In contrast to defects in inner ear function, however, auditory processing disorders (APDs)-which can affect up to 2-3% of school-children-are not easily identified with basic screening programs and must be diagnosed using special tests. Although such psychoacoustic tests are available, the scores achieved depend highly on the social, cultural, and linguistic characteristics of the population, and norms must be established for each population separately. Reference values are still lacking for the Polish population, especially for children in school-age, so that practitioners must interpret test scores themselves, often intuitively or using potentially biased thresholds from other countries.

We investigated a sample of 94 Polish schoolchildren with normal hearing, divided into four age groups: from 7 years-olds to 10 years-olds. All children had no speech or language development disorder, learning problem, or symptom of APD. Participants were volunteers who had previously taken part in a large screening study. The group consisted of 56 girls (60%) and 38 boys (40%) with an average age of 8.6 years (SD = 1.1). The test battery included the Duration Pattern Test (DPT), Frequency Pattern Test (FPT), Time-Compressed Speech Test (CST), and Dichotic Digit Test (DDT).

The scores on all tests increased consistently with age. The difference between each age-group for DPT, CST, and left- and right-ear DDT tests was significant (Kruskal-Wallis test, p-values = 0.002, 0.006, 0.005, 0.020, respectively), but the effect of age on the FPT test was not (p-value = 0.143). The analysis showed a clear and significant separation between a merged group of ages 7 and 8 and another of ages 9 and 10. We, therefore, propose, for each test, separate reference values for these two particular age-groups. Using thresholds based on a 10% quantile, we offer the following reference values for ages 7-8 and 9-10 respectively: DPT, 28.5% and 53.8%; FPT, 18.5% and 27.5%; CST, 68.6% and 77.2%; left-ear DDT, 34.3% and 52.5%; right-ear DDT, 56% and 72.5%.

The scores on psychoacoustic tests to diagnose APD differ between cultures and linguistic backgrounds. Clinicians should, therefore, use norms that have been designed for the population most similar to their patients. Here, we report the use of a test battery designed for the Polish language that accounts for various aspects of APD when screening school children. Together with a full methodology of those tests, we provide norms that can be used as cut-offs in clinical diagnosis. Practitioners are invited to use them to obtain more accurate, evidence-based decisions.