Data reduction for cough studies using distribution of audio frequency content

Antony Barton,Jaclyn A Smith,Kimberley Holt,Patrick Gaydecki

doi:10.1186/1745-9974-8-12

Antony Barton, Jaclyn A Smith + Show 2 more

Open Access

https://doi.org/10.1186/1745-9974-8-12

Copy DOI

Abstract

BackgroundRecent studies suggest that objectively quantifying coughing in audio recordings offers a novel means to understand coughing and assess treatments. Currently, manual cough counting is the most accurate method for quantifying coughing. However, the demand of manually counting cough records is substantial, demonstrating a need to reduce record lengths prior to counting whilst preserving the coughs within them. This study tested the performance of an algorithm developed for this purpose.Methods20 subjects were recruited (5 healthy smokers and non-smokers, 5 chronic cough, 5 chronic obstructive pulmonary disease and 5 asthma), fitted with an ambulatory recording system and recorded for 24 hours. The recordings produced were divided into 15 min segments and counted. Periods of inactive audio in each segment were removed using the median frequency and power of the audio signal and the resulting files re-counted.ResultsThe median resultant segment length was 13.9 s (IQR 56.4 s) and median 24 hr recording length 62.4 min (IQR 100.4). A median of 0.0 coughs/h (IQR 0.0-0.2) were erroneously removed and the variability in the resultant cough counts was comparable to that between manual cough counts. The largest error was seen in asthmatic patients, but still only 1.0% coughs/h were missed.ConclusionsThese data show that a system which measures signal activity using the median audio frequency can substantially reduce record lengths without significantly compromising the coughs contained within them.

Highlights

Cough is the commonest symptom reported by patients to doctors and presents as part of the symptom complex of many respiratory diseases [1,2]
Subjects We studied 20 subjects (10 male, 10 female), 5 each from groups of healthy volunteers, sufferers of chronic cough, chronic obstructive pulmonary disease (COPD) and asthma, see Table 1
We have previously demonstrated an excellent level of agreement between trained manual cough counters in a variety of diseases [6,10,11]

Summary

Introduction

Cough is the commonest symptom reported by patients to doctors and presents as part of the symptom complex of many respiratory diseases [1,2]. Until recent years the study of cough has been restricted by a lack of useful measurement tools, relying mainly upon subjective reporting of cough severity. The development of portable digital sound recording devices has allowed the number of cough sounds to be counted over extended time periods, providing an objective measure of cough rate and new insights into its determinants [3,4,5,6]. Recent studies suggest that objectively quantifying coughing in audio recordings offers a novel means to understand coughing and assess treatments. Manual cough counting is the most accurate method for quantifying coughing. The demand of manually counting cough records is substantial, demonstrating a need to reduce record lengths prior to counting whilst preserving the coughs within them. This study tested the performance of an algorithm developed for this purpose

Objectives

Methods

Results

Conclusion