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This study investigates the propagation of sound from a source in the chest to the chest wall.

The methodology of the study will be to place a sound source at a known location in the chest and measure the acoustic response on the posterior chest wall with an acoustic sensor array.

The sound source will be created by playing sound down the working channel of a bronchoscope and located anatomically using direct imaging.

Subjects will be selected for the study by asking patients undergoing a bronchoscopy procedure whether they would be willing to take part in the experiment in addition to their standard procedure.

Procedures will take place in the Bronchoscopy Unit at Addenbrooke's hospital in Cambridge. The Unit runs regional speciality clinics in severe chronic obstructive pulmonary disease, asthma, lung cancer, bronchomalacia and interstitial lung disease and has a nationally significant interventional bronchoscopy service.

A subsidiary part of the study (Part A) will collect sound recordings from healthy volunteers and patients with common respiratory diseases using the same acoustic sensor array. This is to create a database of lung sounds and quantify inter-subject variability.

The study will last approximately 30 months.

The study has two parts, A and B. Both parts are observational studies of the sounds heard at the chest as recorded by an acoustic array.

In Part A, healthy volunteers and patients at Addenbrooke's hospital will have the chest sounds at their back recorded using an electronic-stethoscope array. This will be done in a single session lasting approximately 30 minutes. 50 healthy volunteers and 100 patients will be included.

In Part B, 50 patients undergoing a bronchoscopy at Addenbrooke's hospital will have their bronchoscopy extended by 5-10 minutes so that sounds can be played through the working channel of the bronchoscope and recorded by a microphone array at the posterior chest. Part B will investigate 25 patients with structurally 'normal' lungs (for example patients with Chronic Cough) (Part B(i)), and 25 patients with lung disease that has resulted in an 'abnormal' lung structure (Part B(ii)).

The consultant bronchoscopist will assign the patient to the relevant group based on information from their medical history and their CT scan. For Part B of the study an existing CT scan is an inclusion criterion. CT scans will not be carried out specifically for this study.

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Male of Female, aged 18 years or above.
• Part A(i) Healthy volunteer with no history of smoking, recreational drug use or respiratory disease.
• Part A(ii) Patient admitted to Addenbrooke's with a pulmonary disease resulting in crackles and/or wheezes (as diagnosed by a qualified medical practitioner).
• Part B Patient admitted to Addenbrooke's hospital for a bronchoscopy procedure.
• Part B Appropriate recent imaging available: chest CT within 3 months.
• Part B(i) Lung structure deemed 'normal' by pulmonary physician based on CT scan and medical history.
• Part B(i) Lung structure deemed 'abnormal' by pulmonary physician based on CT scan and medical history.

Exclusion Criteria:

• Informed consent is not given.
• Subject is under 18 years old.
• WHO performance status >2.
• Subject is pregnant.
• Subject is unable to understand English.
• Part A(i) History of smoking, recreational drug use or respiratory disease.
• Part A(ii) Condition judged to have no effect on breathing sounds. Patient with crackle or wheeze when quota for crackle or wheeze patients respectively is fulfilled.
• Part B Risk associated with prolonging bronchoscopy procedure judged to be too high by medical professional.
• Part B Appropriate recent imaging (chest CT within 3 months) not available.

Part A(i) 50 healthy volunteers, taken from the general population.

Part A(ii) 100 patients, taken from the population of patients at Addenbrooke's Hospital, Cambridge, UK with clear evidence of wheezing and/or crackles due to respiratory disease. We will aim to recruit approximately 50 patients with wheezing and 50 patients with crackles.

Part B(i) 25 patients, taken from the population of patients on the bronchoscopy list at Addenbrooke's Hospital, Cambridge, UK.

Part B(ii) 25 patients, taken from the population of patients on the bronchoscopy list at Addenbrooke's Hospital, Cambridge, UK

Non-identifiable patient data will be used in publications and made available on the University of Cambridge's data repository DSpace when the results of the study are published.