Can a common heart drug quiet the rage of misophonia?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 18-65. * Able to complete study visit(s) in Littleton, CO. * Able to give informed consent. * Participant reports clinically significant misophonia symptoms, as determined by answers on the standardized "Misophonia Trigger Screening Questions for Participants" form (described separately in the protocol). Specifically, participants must demonstrate relevant misophonia trigger responses that meet pre-specified minimum severity criteria detailed on this form. * A-MISO-S rating scale severity criterion: Participants must score at least a moderate ("2") or higher on question 2 and question 3 of the Amsterdam Misophonia Scale (A-MISO-S) at screening, since this indicates clinically meaningful misophonia severity for study eligibility. * Able to communicate misophonic distress in writing and reasonably participate in our outpatient clinical setting, meaning able to tolerate being in this outpatient clinical setting, follow the clinic rules for all patients and guests, and respond in an understandable fashion to questions administered to them. * Must agree to follow study clinician advice and seek additional care outside of this clinic if advised (e.g., if advised to seek help from emergency services for a potentially serious adverse reaction). * English fluency Exclusion Criteria: * Current use of scheduled propranolol for any condition. * Any of the known contraindications for taking propranolol: * cardiogenic shock * sinus bradycardia (\<50 bpm) * greater than first degree heart block * BP below 90/60 * asthma / bronchial asthma that requires treatment or medication, and/or has caused clinical concerns within the last 5 years * Other heart conditions that require ongoing medical treatment * Participants with any of the following relative contraindications for taking propranolol: * participants who have active anorexia, purging, or who are underweight (\<18.5 BMI) * Active drug or alcohol use within the last 48 hours prior to study participation, or active drug withdrawals * A history of untreated diabetes or other endocrine disorders that could be harmed by exposure to propranolol * history of cardiovascular disease or stroke, or symptomatic blood disorders such as anemia * history of any other severe physical or neurological conditions that may affect their ability to participate in the study * Participants with liver or kidney disease that would be affect or be affected by the study drug * Participants may, depending on the circumstances as decided by the study clinician, be excluded for any of the following conditions that may have adverse reactions to propranolol, including: Raynaud disease or other peripheral vascular disease, Pheochromocytoma, Psoriasis, Thyroid disease (untreated, and affected by propranolol), Unexplained dizziness, Oxygen level below 91%, Respirations below 12 or above 20 * Participants taking any other medications that could interfere with the effects of propranolol, as determined by the study clinician (e.g. other beta blockers, alpha blockers,prazosin, clonidine, guanfacine, diuretics, calcium channel blockers, acute us of anti-anxiety medications; other medications that interfere with the adrenergic system; or medications that have a significant effect on propranolol's pharmacology that would normally affect dosing in clinical practice * Allergy or sensitivity to propranolol, placebo ingredients, and/or capsule ingredients. * Pregnant or nursing. * Any of the following in 30 days prior to enrollment: active psychosis, suicidal/ self-harming / homicidal thoughts, bipolar mania, panic attacks, traumatic dissociation, Post-Traumatic Stress Disorder (PTSD) flashbacks, or psychiatric hospitalization. * Participant self-reports or clinical interview identifies any misophonia-triggered reactions within the past year that posed a significant risk to health or safety, including suicidal or homicidal ideation, or uncontrolled physical behaviors (e.g., self-injury, aggression toward others, throwing objects, screaming, or fleeing uncontrollably). This criterion is assessed via direct structured questioning during participant screening interviews and review of participant self-reports on standardized screening questionnaires. * Misophonia trigger symptoms are determined by a medical provider to be better explained by a condition other than Misophonia, such as hyperacusis or phonophobia. * Inability to hear routine sounds and communication (ie severe hearing impairment), only if it interferes with ability to hear the misophonia triggers on the video. * Participants who are triggered by the sound of water running or a car alarm (our control videos)