Abstract
Tracheal sounds have received a lot of attention for estimating ventilation parameters in a non-invasive way. The aim of this work was to examine the feasibility of extracting accurate airflow, and automating the detection of breath-phase onset and respiratory rates all directly from tracheal sounds acquired from an acoustic microphone connected to a smartphone. We employed the Samsung Galaxy S4 and iPhone 4s smartphones to acquire tracheal sounds from N = 9 healthy volunteers at airflows ranging from 0.5 to 2.5 L/s. We found that the amplitude of the smartphone-acquired sounds was highly correlated with the airflow from a spirometer, and similar to previously-published studies, we found that the increasing tracheal sounds' amplitude as flow increases follows a power law relationship. Acquired tracheal sounds were used for breath-phase onset detection and their onsets differed by only 52 ± 51 ms (mean ± SD) for Galaxy S4, and 51 ± 48 ms for iPhone 4s, when compared to those detected from the reference signal via the spirometer. Moreover, it was found that accurate respiratory rates (RR) can be obtained from tracheal sounds. The correlation index, bias and limits of agreement were r2 = 0.9693, 0.11 (−1.41 to 1.63) breaths-per-minute (bpm) for Galaxy S4, and r2 = 0.9672, 0.097 (–1.38 to 1.57) bpm for iPhone 4s, when compared to RR estimated from spirometry. Both smartphone devices performed similarly, as no statistically-significant differences were found.
Highlights
Respiratory sounds vary and they include breath sounds, adventitious sounds, and sounds from the respiratory muscles, excluding voiced sounds during breathing, according to the European RespiratorySociety (ERS) Task Force Report [1]
We propose the use of smartphones to develop a Computerized Respiratory Sound Analysis (CORSA) system that satisfies the current standards in the field
Several features have been used to estimate the airflow from the tracheal acoustical information, and the Shannon entropy of the tracheal sounds was found to provide better performance compared to other models based on the signal envelope and average power [30,31]
Summary
Respiratory sounds vary and they include breath sounds, adventitious sounds, and sounds from the respiratory muscles, excluding voiced sounds during breathing, according to the European RespiratorySociety (ERS) Task Force Report [1]. Lung sounds are all respiratory sounds heard or detected over the chest wall or within the chest, including breathing and adventitious sounds detected at this location [1]. Tracheal sounds are those heard or detected over the extrathoracic part of the trachea [1]. Tracheal sounds exhibit well defined inspiratory and expiratory phases and their frequency contents are higher compared to lung sounds [3]. It has been found that inspiratory and expiratory phases have similar frequency contents for tracheal sounds [3,4].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
