Speech-on-speech masking and psychotic symptoms in schizophrenia

People with schizophrenia have impairments of target-speech recognition (TSR) in noisy environments with multiple people talking. This study investigated whether the TSR impairment in schizophrenia is associated with their impaired auditory working memory or certain psychotic symptoms. Thirty participants with schizophrenia (mean age = 35.2 ± 12.7 years) and 30 demographics-matched healthy controls (mean age = 32.9 ± 10.9 years) were tested for their TSR against a two-talker-speech masker. Auditory working memory and memory capacity were evaluated using the Paced Auditory Serial Addition Test (PASAT) and Digit Span Test. Psychotic symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). The results showed that participants with schizophrenia had higher TSR threshold (i.e., poorer TSR performance) and poorer PASAT scores than their healthy controls. Moreover, positive correlations (with age, sex, educational years, ill-duration, and dosage of antipsychotics controlled as covariates) were revealed between the TSR threshold and the PANSS-positive syndrome (especially delusion), and between the TSR threshold and the PANSS-negative syndrome (especially lack of spontaneity in speech and passive-apathetic-social withdraw). However, neither the PASAT nor the forward digit span exhibited significant correlations with the TSR. This study provides evidence that the TSR impairment (i.e., augmented vulnerability to informational speech masking), which reflects disorganization of speech information processing (inability in either inhibiting unrelated speech signals or capturing the wanted speech signals), is specifically associated with the severity of delusion, poverty of speech, and hypobulia, suggesting the potential value of the TSR impairment used for predicting certain core symptoms of schizophrenia.