Summary
The goal of this single-cohort clinical trial is to learn whether a smartphone-based Cough Management (CM) program can reduce cough frequency and burden in adults (21-80 years) who have refractory or unexplained chronic cough. 
The main questions it aims to answer are:
* Does four weeks of using the CM feature in the CoughPro app lower objective cough rate (coughs per hour) compared with each participant's one-week baseline? 
* Does the program also lessen cough intensity (bout metrics) and improve patient-reported quality-of-life scores on the Leicester Cough Questionnaire and PGI-S?
Participants will:
* Wear a Hyfe CoughMonitor smartwatch continuously for 6 weeks (1-week baseline, 4-week intervention, 1-week follow-up), charging it nightly. 
* Complete science-based in-app CM lessons based on behavioral cough-suppression therapy and practice the techniques during the 4-week intervention.
* Fill out online questionnaires (LCQ and PGI-S) at baseline and at the end of Week 4.
* Join a brief exit interview, then return the smartwatch and receive a compensation voucher.
Eligibility Criteria
Age Range: 21 years to No maximum
Inclusion Criteria:
* Age 21 or older.
* Currently suffering from a cough that started at least 8 weeks ago that is largely unproductive (i.e., at least 50% of the time the cough produces zero mucus that needs to be spit out or swallowed).
* Normal chest X-ray or chest CT scan at some point that was prescribed specifically for their cough.
* At least one physician visit for cough with standard-of-care therapy but inadequate symptom relief.
* Stability of treatment: willing to avoid new cough treatments during study or report changes if they occur.
* Ability to comply: willing/able to wear the watch daily for the required duration of study and to complete all required questionnaires.
* Informed consent: understanding of the study procedures and agreement to comply with protocol.
Exclusion Criteria:
* Recent upper respiratory infection (past 4 weeks).
* History of hemoptysis (coughing up blood) since onset of the current cough.
* Current smoker (incl. vaping) of any substance.
* ≥10 consecutive pack-years smoking history within \<10 years prior to screening.
* Diagnosed with a chronic lung condition (COPD, emphysema, lung cancer, IPF, chronic bronchitis, asthma). Note: Suspected asthma without confirmed diagnosis or benefit from asthma therapy is not an exclusion.
* Current or past head/neck cancer.
* Difficulty swallowing.
* On ACE inhibitors, such as Benzapril (Lotensin), Captopril (Capoten), Enalapril/Enalaprilat (Vasotec oral and injectable), Fosinopril (Monopril), Lisinopril (Zestril and Prinivil), Moexipril (Univasc), Perindopril (Aceon), Quinapril (Accupril), Ramipril (Altace), and Trandolapril (Mavik)
* Prior treatment for cough by a speech-language pathologist.
* Living with another individual with a frequent cough that would interfere with monitoring.
* Participation in any cough intervention study within 30 days or 5 half-lives of the intervention.
* Major scheduled surgery during the study period.