This semester marks an exciting moment for the Swarthmore Music Department as it will be the first performance of Critical Mass as the College’s newest official musical ensemble. They will perform on December 7th at 3 p.m. in Lang Concert Hall — the event is free and open to the public. Critical Mass is a small vocal ensemble with a big sound who perform advanced choral works from the Medieval and Renaissance periods.

While this will be the first time the group performs as the ‘Critical Mass’ ensemble, they have existed previously as a Fetter Chamber Music group. They got their start in 2016 when Professor James Blasina was a new faculty member at Swarthmore teaching courses on Medieval and Renaissance music.  “There was a group of students who approached me and wanted to have more experience singing this repertoire in addition to studying it,” said Blasina. Forming a Fetter group allowed Blasina and his students to begin engaging with the music on a weekly basis, but over the years the ensemble outgrew the Fetter model.  “We needed more institutional support and frameworks to be able to have more rehearsal time. Students were putting a lot into it but not getting as much out of it as they could if it were an official ensemble,” Blasina remarks.

Now that Critical Mass exists as its own ensemble, “students can get ensemble credit for it. We have three hours of rehearsal a week,” said Blasina. This allows the nine-person ensemble to engage more deeply with the music.“We're able to do more repertoire, more complicated repertoire, more interesting repertoire.”

Ashley Rehrig ‘26 describes how being an official ensemble has benefited the group: “I thoroughly enjoy the connection we’ve formed as an ensemble, with returning and brand new members … the community we have created is present as we delve into the pieces and create beautiful harmonies for every audience member to enjoy and soak in.”

Critical Mass’ name is a play on words. The original members were all highly involved with STEM fields and so one meaning of ‘critical mass’ is the physics definition regarding nuclear reactions. The other is tied to the music of the ensemble. Polyphonic settings of the texts for the Latin mass are a staple of the performance repertoire in Medieval and Renaissance music.

The ensemble will perform several works from the Medieval and Renaissance periods, ranging from sacred to secular music like Latin motets and madrigals. The composers featured for this semester include Orlande de Lassus, Tomás Luis de Victoria, William Byrd, and Salamone Rossi. Ensemble member Elijah Santos ‘26 says: “I'm excited to sing Tomás Luis de Victoria's justly famous motet O magnum mysterium. This motet is based on the Gregorian responsorial chant of the same name, which we will also sing as a double feature.”

The relatively small size of the ensemble presents advantages and challenges. “On one hand, our work is very collaborative. We talk about artistic decisions that we're making together because an ensemble of this size can do that. On the other hand, it can be scary because every singer has to know their part really well. It’s very exposed,” says Blasina.

For anyone interested in joining the ensemble, Blasina says: “[Critical Mass is for you] if you're a musician who is really interested in a collaborative rehearsal process, in musical independence within an ensemble, in really ‘getting your hands dirty’ with the repertoire”

Critical Mass will perform on December 7th at 3 p.m. in the Lang Music Concert Hall at Swarthmore College. The concert is free and open to the public.