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.

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.