Inclusion Criteria:  Age between 18 and 50 DSM-V diagnosis of schizophrenia or schizoaffective disorder Willing to provide informed consent  Auditory Cognitive impairment demonstrated by:  a .MCCB composite domain score less than or equal to 0.5 standard deviation below normal (T score less than or equal to 45) b. And at least one of the following:  MCCB verbal memory domain score less than or equal to 0.5 standard deviation below normal (T score less than or equal to 45) Tone matching score of less than or equal to 77.7% Clinically stable for 2 months (CGI less than or equal to 4) Moderate or lower cognitive disorganization (PANSS P2 less than or equal to 4) Medically stable for study participation Willing to use qualified methods of contraception for the study duration and up to 2 months after its end Fluent English speaker Normal hearing Visual acuity corrected to 20/30 An estimated Glomerular Filtration Rate (GFR) greater than or equal to 60 Taking an antipsychotic medication other than clozapine at a stable dose for at least 4 weeks Judged clinically not to be at significant suicide or violence risk  Exclusion Criteria:  Substance abuse (excluding nicotine) within last 60 days ECG abnormality that is clinically significant in the context of study participation in the opinion of the study cardiologist Current clozapine use. Clozapine is excluded for two reasons: to avoid the potential confound of treatment resistant patients and because of clozapine's intrinsic NMDA agonist Participation in study of investigational medication/device within 4 weeks Pregnant women or women of child-bearing potential, who are either not surgically-sterile or for outpatients, using appropriate methods of birth control. Women of child-bearing potential must have a negative serum beta-hCG pregnancy test at screening. Presence of positive history of unstable significant medical or neurological illness Positive toxicology screen for any substances of abuse Subjects with suicidal ideation with intent or plan (indicated by affirmative answers to items 4 or 5 of the Suicidal Ideation section of the baseline C-SSRS) in the 6 months prior to screening or subjects who represent a significant risk of suicide in the opinion of the investigator