Spectral degradation influences phonological memory in typically hearing adults

Phonological processing is a fundamental component of language, can be impaired in people with hearing loss, and involves several confounded subprocesses. The purpose of this study was to systematically examine several phonological subprocesses - i.e., the spectral quality of auditory input and phonological short-term and long-term memory - in order to better understand how they interact with one another in basic linguistic tasks. Using an experimental, within-subjects design, 30 typically-hearing adults completed nonword repetition (NWR) and auditory lexical decision (ALD) tasks varying in spectral quality (normal versus spectrally-degraded), consonant age of acquisition (CAoA; i.e. early-acquired versus late-acquired consonants), syllable length (NWR task), and lexical status (ALD task). In NWR, spectral degradation muted the word length effect, though performance differed depending on how familiar participants were with the degraded stimuli. ALD findings showed that the magnitude of the degradation effect varied between stimuli comprising early-acquired versus late-acquired consonants. The robust effect of spectral degradation on phonological short-term and long-term memory provides a model of the interactive nature of these subprocesses in typical adults. Future work with populations with hearing loss can provide a comparison to help understand how the typical and clinical phonological systems differ.