SHARPEN - Parkinson's Disease Dementia

Inclusion Criteria: * Adults, age 50 years of older, diagnosed with Clinically Established or Clinically Probable Parkinson's disease according to the MDS Clinical Diagnostic Criteria * Participants with a clinical diagnosis of probable Parkinson's disease dementia ( PDD) using criteria defined in Emre et al., 2007 and in accordance with procedures defined in Dubois et al., 2007 (allowing for diagnosis of PD defined in Step 1 to be according to MDS Clinical Diagnostic criteria instead of the Queen Square Brain Bank Criteria) * Participants must be able and willing to consent to participate in the study and comply with all study requirements. If the participant is unable to consent due to limited capacity, a Legally Authorized Representative (LAR) must consent. * Participants and investigators must expect that the participant will be able to remain on a stable regimen of concomitant therapies used for the management of PD and not to introduce new medications used to treat PD (motor or non-motor symptoms) during the study. * The principal investigator, or designee, must have confidence in the participant's ability to reliably use the TNM™ device, and to understand and complete the assessments (provided in English only) within a given on-state. * Participant must have a study partner (defined as someone who sees the participant for more than three hours a day, 5 times per week) that is willing to consent and participate in the trial. Exclusion Criteria: * Participant anticipates being unable to attend all visits and complete all study activities during the trial. * Women of child-bearing potential who are pregnant or plan to become pregnant during the course of the trial * Has any significant co-morbidity/condition, planned surgery or participation in another clinical trial which may either prevent safe participation in the study procedures or interfere with the evaluation of safety or efficacy of the study Device as a potential treatment for PDD * In the Investigator's opinion, has severe dementia, (e.g., Mini Mental State Exam score (at screen visit) \<15 and/or requires significant assistance with activities of daily living due to cognitive deficits) * Has experienced a myocardial infarction, angina, or stroke within the past 12 months, transient ischemic attack (TIA) within the past 6 months or has a documented aspiration event in the medical records * Are receiving late-stage therapies for PD (e.g., deep brain stimulation or pump infusion therapies) or are being treated with another neurostimulation device * History of interventional brain surgery or have received magnetic resonance guided high intensity focused ultrasound * Demonstrate suicidality at screening (scores ≥ 4 on the Columbia- Suicide Severity Rating Scale Baseline "In the past Month" section) * Have been previously diagnosed with either clinically meaningful central vestibular dysfunction (lifetime) or have experienced clinically meaningful peripheral vestibular dysfunction within the last 12 months * Have active ear infections, perforated tympanic membrane or labyrinthitis, as identified by a general ear examination * Use any drugs excluded in the Excluded Medications List * Use of antipsychotic medication(s) listed in the Approved Concomitant Medications (i.e., pimavanserin and quetiapine) that have not been taken for more than 180 days and does not have medical record documentation of normal QTc interval (i.e., no prolongation of the QTc interval) as measured via electrocardiogram after starting the medication * Have active ear infections, perforated tympanic membrane or labyrinthitis, as identified by a general ear examination performed by medically qualified Investigators or have chronic tinnitus that has been ongoing for at least 3 months * Have a cochlear implant, myringotomy tubes or hearing aids that cannot be easily/reliably removed for treatment * Clinically significant abnormalities in B12, thyroid function, blood count, comprehensive metabolic panel or urinalysis results tested at the study screen. Screening tests are not required in cases where test results within normal range within 6 months of study screen are documented in the medical records.