A Review of Mask Types for Sound Quality

The University of Massachusetts Amherst has instituted a mask mandate for the start of the Fall 2021 Semester. The mandate goes into effect today (August 11th) and will be reviewed in mid-September. During this mandate, masks will be required in all public indoor spaces which includes faculty members who are actively teaching. Making sure that you are clear in speech is critical, particularly in large lecture halls. To that end, Heath Hatch and I did some tests on various types of masks. I am posting the results here for folks’ reference.

Overview of the Mask Types

Mask #1: A Simple Cloth Mask

This is a simple cloth mask. I like these for simple around-town use as I find them comfortable and, due to their crush-ability, easy to carry around.

Video overview of the simple cloth mask.

Pros:

Comfortable (at least for me).
Easy to breathe.
Easy to wash.

Cons:

Falls off your face when talking!
Some people find the closeness to the face uncomfortable.
Only one layer of fabric.

Mask #2: A More Elaborate Cloth Mask

This mask has two thinner layers and a metal piece for the nose.

An overview of the more sophisticated cloth mask.

Pros:

Stays on face while lecturing.
Comfortable.
Easy to breathe.
Multiple fabric layers.

Cons:

None really.

Mask #3: A Cone-Style KN95

This is cone-shaped KN95 mask. The particular brand (no brand endorsement implied) is Bio-th which was permitted under the FDA’s Emergency Use Authorization.

Overview of cone-style KN95.

Pros:

Stays on face while lecturing.
Stays away from face while talking, making articulation easier.
Easy to breathe.
Tight seal.
Kn95 by FDA EUA.
Folding makes it easy to carry.

Cons:

The tight seal makes it a bit of a jaw workout to talk. Your jaw will be tired by the end of the day at first.

Review of Sound Quality

A large lecture hall that provides the teaching environment for P132

We tested the masks in the empty Hasbrouck 20 lecture hall. The lecture hall has a concrete roof and floor with brick walls and hard-plastic chairs resulting in a lot of echo. Given that the room was empty, we are not sure that the results will be representative when the room is full, but we cannot find that out until the students come back!

The sound checks for the different mask styles.

Summary and Recommendation

My Pick: Mask #3 – A Cone-Style KN95

This particular mask was the overall winner. The mask stayed on while speaking and the cone shape resulted in the clearest voice while using a microphone in the empty Hasbrouck 20.

Mask #1, the simple cloth mask kept slipping off the nose while talking and Mask #2, the more sophisticated cloth mask, had noticeably muffled sound quality.

Future work and mask equity

The opacity of the mask results in students obtaining less information because they cannot see the instructor’s lips. This is particularly true for Deaf and other students with hearing difficulties. I plan to try a mask with a clear window in the future to see if this feature works and its impact on sound quality.

My Quantum Life – A Review

The seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspends his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency. Thus, if learning the truth is the scientist’s goal, then he must make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.
Ibn al-Haytham, father of optics and the Scientific Method,
Kitāb al-Manāẓir (كتاب المناظر), published 1011-1021,
Quoted in My Quantum Life: My Unlikely Journey from the Street to the Stars by Hakeem Oluseyi

I just finished listening to the audio-book of My Quantum Life: My Unlikely Journey from the Street to the Stars by Hakeem Oluseyi. This book was just fantastic. While, Prof. Oluseyi is clearly writing for a general audience, he does not shy away from the physics details. Having a physics (and academic) background, I suspect, makes the book more enjoyable.

Brokk Toggerson contributes to ACUE Inclusive Teaching for Equitable Learning Micro-credential

Brokk Toggerson was recommended by the UMass Amherst Center for Teaching and Learning to contribute to a micro-credential on Inclusive Teaching for Equitable Learning developed by the Association of College and University Educators (ACUE). Brokk participated in an in-depth interview on a variety of questions. Ultimately, ACUE selected a section on developing effective teams for incorporation into their lesson.

Fishbone Root Cause Analysis Protocol

This document from the Minnesota Department of Education describes this interesting protocol which describes a procedure for really determining the fundamental causes of a problem (such as student struggle) under the assumption that treating the cause (as best as possible) is more effective than treating just the symptoms. The basic idea is to work to you find a “significant cause that can, in fact, be changed.”

I find this to be an interesting perspective to share when we consider the myriad of unique challenges that our students are facing during this time of COVID-19.

My letter to students regarding the change to UMass’s reopening plan

Last night, the University announced a change to their reopening plan. In short, the goal is to reduce the number of students on campus and in the surrounding area. While I applaud the efforts to mitigate the spread of the virus, and the science-based decision making, I felt it was important to reach out to my students to both acknowledge the stress they were undoubtedly feeling with such a change so close to the start of the semester. I also want to point out that there was still an option for those students who had nowhere else to go as I felt that this message was (understandably) minimized in the announcement.

My letter to my students is below. I post it in case anyone else wants to use it as a template.