STEM-PD Open Label Extension (OLE)

Inclusion Criteria: * Completion of the study activities in the STEM-PD RCT trial (see STEM-PD RCT eligibility criteria noted below). * Participants must be willing and able to give consent to participate in the study trial. * 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 motor and non-motor symptoms and not to introduce new medications used to treat motor or non-motor symptoms associated with PD during the first three months of the OLE (Day197). Exclusion Criteria: * Participant anticipates being unable to attend all visits and complete all study activities. * Has a planned surgery scheduled to occur during the first 90 days of the OLE that would typically be followed with a prescription for pain management STEM-PD RCT Eligibility criteria: Inclusion: 1. Adult participants (aged 18 - 85 years inclusive). 2. Have been diagnosed with PD according to the UK Brain Bank Criteria (allowing for an exclusion in Step 2 for "more than one affected relative"). 3. Participants must have demonstrated a sustained positive response to DRTs (e.g., levodopa, dopamine agonists or monoamine oxidase inhibitors) defined as either good or excellent responses (50-100%) for at least one year or moderate responses (30-49)% for at least three years prior to Screen. 4. Participant reports limitation or clinician-investigator determined limitation, based on knowledge of medical history, to one or more activities of daily living (e.g., writing, walking, bathing, dressing, eating, toileting, etc.). 5. Participants must be able and willing to consent to participate in the study for the RCT and OLE. 6. Participants must be willing and able to comply with study requirements. 7. Participants must have at minimum a moderate burden of NMS (i.e., MDS-UPDRS part Ia and part Ib summed total score ≥ 9) at study screen to avoid floor effects for the primary endpoint (MDS-NMS). 8. The principal investigator or designee must have confidence in the participant's ability to reliably use the TNM™ device, understand the assessments (provided in English only) and to complete the assessment battery within a given on-state period. 9. Must have a study partner (defined as someone who sees the participant for more than one hour a day, 3x per week) that is willing to consent and participate in the trial. 10. Participants must have capabilities to use and access smartphones for the collection of some study data and/or tablets or computers for access to telemedicine platforms. 11. Must be willing to answer questions related to sexual interest, arousal and performance in an interview with study staff. Exclusion: 1. Women of child-bearing potential who are pregnant or plan to become pregnant during the course of the study • Women of child-bearing potential (i.e., are not yet either 3 years removed from their first menopausal symptom or 12 months removed from last menses), who are not abstinent or exclusively in same sex relationships must: * test negative for pregnancy as indicated by a negative urine pregnancy test; * agree to use an approved contraception method listed in section 5.3.3 for the entirety of the RCT and OLE; 2. Have a history or prior diagnosis of dementia or adjusted score ≤ 20 on the Montreal Cognitive Assessment (MoCA) at the screening visit. 3. Have experienced a myocardial infarction, angina or stroke within the past 12 months or a transient ischemic attack (TIA) within 6 months. 4. Are receiving deep brain stimulation therapy. 5. Are treated with a pump for continuous delivery of dopamine replacement therapy. 6. Have received MRI guided high intensity focused ultrasound within the past 12 months. 7. Experience frequent falls (defined as 2 or more falls in the past month related to Parkinson's disease). Parkinson's falls are defined as falls associated with bradykinesia, freezing, turning, change in posture and postural dizziness and do not include accidental falls. 8. Work night shifts. 9. Has any significant co-morbidity or illness which in the opinion of the investigator would prevent safe participation in the study, compliance with protocol requirements or which presents with symptoms that are also common in PD. 10. Demonstrate suicidality at screening (scores ≥ 4 on the C-SSRS Baseline in section "Suicidal Ideation" (In the past Month)). Participants that respond affirmatively to question 4 or 5 (In the past Month) should receive a referral for mental health counseling according to local site regulations and standards. 11. Use a hearing aid that is implanted or that cannot be easily removed and replaced. 12. Have a cochlear implant or myringotomy tubes. 13. Have chronic tinnitus that has been ongoing for at least 3 months and causes significant impairment of communication and/or impairment of activities of daily living. 14. Have previously been diagnosed with traumatic brain injury with ongoing sequela. 15. Have been diagnosed with a co-morbid neurological disorder that may present with symptoms overlapping with PD (e.g., stroke, brain tumor, epilepsy, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, atypical Parkinsonism or aneurysm). 16. 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. For this purpose, clinically meaningful is defined as vestibular dysfunction which causes at least a minimal impairment in the individual activities of daily living (e.g., dressing, bathing, preparing food, conducting household chores, work or recreational activities). 17. In the Investigator's opinion, currently abuse alcohol, abuse drugs (including legal, illegal or prescribed drugs) or have a history of alcohol or drug dependency within the past 5 years or use any drugs excluded as noted in the Excluded Medications List 18. Have unresolved complications from a previous surgical procedure at the baseline visits, such as swelling or persistent pain, that requires medical intervention. 19. Have active ear infections, perforated tympanic membrane or labyrinthitis, as identified by a general ear examination performed by medically qualified Investigators. 29\. Have a recent history of frequent ear infections (≥ 1 per year over the past two years). 21\. Are currently enrolled or have participated in another interventional clinical trial within the last 30 days. 22\. Have had eye surgery within the previous three months or ear surgery within the previous six months.