The latest issue of Choral Journal is online and features an article titled “Acoustical, Psychoacoustical, and Pedagogical Considerations for Choral Singing with COVID-19 Health Measures” by by John Nix, Harald Jers, and Sten Ternström. You can read it in its entirety online at acda.org/choraljournal. Following is a portion of the article. Please read the entire article for more on these recommendations.
Singing outdoors has the potential to remove much if not all of the typical reverberant character of a performance space on the choir’s sound (as experienced inside and outside of the choir), radically changing the Self to Other Ratio (SOR) experienced by the singers. By the ‘Self ’ signal, we mean those sounds of one’s own voice that arrive directly to one’s own ears. By the ‘Other’ signal, we mean the sum of all other sounds that reach the singer, both direct and reflected. The Self-to-Other ratio is represented as the level difference LSelf – LOther, in dB.
A significant component of Other is the diffuse field of sound reverberating in the room. When singing indoors but with wide spacing, the diff use field dominates the Other sound. When singing outdoors, however, the diff use field is absent, and only the direct sound from the rest of the voices in the choir remains in the Other.
Together with the inverse square law, which states that every time the distance from a sound source is doubled, the intensity reduces by a factor of four, this means that one will hear an Other sound that is weaker and greatly dominated by one’s immediate neighbors in the choir, while the singers who are furthest away might be basically inaudible. This has significant implications for maintaining synchronization within the choir. . . .
Increased spacing between singers increases the SOR, whether indoors or outdoors, and tends to make the bulk of the Other sound consist of the direct sound from each choir member’s immediate neighbors. With increased spacing indoors, the number of singers on a set of risers or on a stage will by necessity need to decrease. From a viral risk reduction standpoint, fewer singers performing at one time is beneficial, although from a perceptual standpoint for the singers, directors should understand that the SOR will increase as the level of the Other sound is reduced. Increasing the distance between choir members also introduces greater delays in the sound of one performer reaching another. . . .
This article discusses Singing Indoors with Increased Ventilation; Wearing Masks; Practical Suggestions for Choral Conductors, Music Educators, Choral Singers; Reinforced Sound; and Other Technological Possibilities.
View this full article (and more!) in the October 2020 issue of Choral Journal, available online at acda.org