Special Report of the NEC Voice and Sound Analysis Laboratory | March 25, 2020
Preliminary Report: Comparing the Audio Quality of Classical Music Lessons Over Zoom, Microsoft Teams, VoiceLessonsApp, and Apple FaceTime
Ian L. Howell,*† Kayla Jane Gautereaux,*† Joshua Glasner,** Nicholas Perna,*** Chadley Ballantyne,**** Theodora Nestorova*
*New England Conservatory of Music, **Coastal Carolina University, ***Mississippi College, ****Stetson University
†Corresponding authors: ian.howell@necmusic.edu, kayla.gautereaux@necmusic.edu
Abstract
Introduction: Recent world events have resulted in the ubiquitous need for the professional music community (including voice teachers) to use online video conferencing platforms to teach applied music lessons in both academic and private studios. While there is a wealth of practical information regarding online applied lesson pedagogy, there has not been a focused inquiry into the digital signal processing limitations of commonly used platforms such as Zoom, Microsoft Teams, VoiceLessonsApp, or FaceTime, nor has there been a comparison of the fidelity of each platform’s audio transmission. This study aims to inform both academic and independent applied music teachers about the capacity of each platform to transmit audio signals and to suggest a path for future online applied instruction.
Method: Nine tests were used to analyze each platform’s ability to transmit audio signal. Tests were chosen to highlight automatic audio gain adjustments, frequency range (i.e. bandpass filters or down-sampling), frequency response, and audio compression.
Results: Each platform was found to alter the audio test signals in unique ways and no one platform passed the audio through without introducing some artifacts or noise. However, the four platforms exhibited noticeable differences along the parameters examined.
Discussion/Conclusion: The Zoom platform (with optional audio settings enabled) seems to provide the highest fidelity to dynamic range and frequency spectrum of the four platforms tested in this study. Microsoft Teams consistently normalized the audio gain regardless of the sound intensity level of the original test signal and removed a significant amount of the spectrum (>7kHz). Both VoiceLessonsApp and Apple FaceTime introduced disruptive automatic gain control when transmitting samples that highlighted dynamic contrast or contained marked sonance. The authors of this study suggest it is imperative for applied music instructors to understand the limitations of any video conferencing platform used for online applied lessons, as well as any equipment used as part of the signal chain (i.e. microphone, audio interface, sound monitor, and video conferencing platform of both the student and teacher). The authors recommend the student perform slow crescendos and decrescendos at a low and high pitch as an effective way to test these limitations. Furthermore, it is suggested that academic institutions prioritize funding the purchase of adequate audio recording and playback equipment for students and teachers in order to approximate an in-person applied lesson experience in the best way possible given the current limitations of video conferencing technology.
Media Files
A/B Comparison Video Files
The following videos demonstrate the differences between the original audio and the received audio for (1) white noise, (2) voices, (3) cello, and (4) violin via each video conferencing platform. These files are 1080p, AAC 256kbps. Please adjust your youtube (little gear on most platforms) setting to playback the highest quality.
Please note the authors used a professional grade signal chain. No platform can fully compensate for the deficiencies of inexpensive or built-in technology. It is our hope that if your results fall short of ours, these samples will help you troubleshoot what is intrinsic vs. extrinsic to the platform.
We recommend reading the complete study (link at top of page) if you have questions related to methodology, technology, or controls.
White Noise
Zoom White Noise
Microsoft Teams White Noise
VoiceLessonsApp White Noise
Apple FaceTime White Noise
Voice
Zoom Voice
Microsoft Teams Voice
VoiceLessonsApp Voice
Apple FaceTime Voice
Cello
Zoom Cello
Microsoft Teams Cello
VoiceLessonsApp Cello
Apple FaceTime Cello
Violin
Zoom Violin
Microsoft Teams Violin
VoiceLessonsApp Violin
Apple FaceTime Violin