Human Factors Study to Validate the User Interface of TOBI Podhaler Using Placebo Capsules

Inclusion Criteria: * Written informed consent or, parent/guardian consent and where applicable pediatric assent, must be obtained before any assessment is performed * Male and female subjects aged 6 years and older * Confirmed diagnosis of CF by one or more of the following tests for CF as documented in the patient's medical history : (1) quantitative pilocarpine iontophoresis sweat chloride test of \> 60 mmol/L or 60 mEq/L, (2) genotype with identifiable CF-causing mutations on both chromosomes, (3) an abnormal nasal transepithelial potential difference characteristic of CF * FEV1 value must be at least 25% of normal predicted values for age, sex, and height as documented in the patient's medical history (historical values within 3 months can be used for this criterion). * Able to comply with all protocol requirements * Clinically stable in the opinion of the investigator Exclusion Criteria: * Subjects currently enrolled in studies that are not considered as observational non-investigational studies * Subjects or caregivers who have used the Podhaler device previously * Hemoptysis more than approximately 60 mL at any time within 30 days prior to enrollment * History of hypersensitivity to the inhaled placebo dry powder (DSPC and/or calcium chloride powder) * Signs and symptoms of acute pulmonary disease, e.g. pneumonia, pneumothorax, bronchospasm, acute respiratory infection * Clinically significant conditions or findings at enrollment that might interfere with the accurate and valid assessment of this study * Subjects or caregivers who are considered potentially unreliable or considered unlikely to be compliant within the trial * Pregnant women