A Simple Method to Obtain Basic Acoustic Measures From Video Recordings as Subtitles

Abstract

Purpose Sound pressure level (SPL) and fundamental frequency (f o ) are very basic and important measures in the acoustical assessment of voice quality, and their variation influences also the vocal fold vibration characteristics. Most sophisticated laryngeal videostroboscopic systems therefore also measure and display the SPL and f o values directly over the video frames by means of a rather expensive special hardware setup. An alternative simple software-based method is presented here to obtain these measures as video subtitles. Method The software extracts acoustic data from the video recording, calculates the SPL and f o parameters, and saves their values in a separate subtitle file. To ensure the correct SPL values, the microphone signal is calibrated beforehand with a sound level meter. Results The new approach was tested on videokymographic recordings obtained laryngoscopically. The results of SPL and f o values calculated from the videokymographic recording, subtitles creation, and their display are presented. Conclusions This method is useful in integrating the acoustic measures with any kind of video recordings containing audio data when inbuilt hardware means are not available. However, calibration and other technical aspects related to data acquisition and synchronization described in this article should be properly taken care of during the recording.