Quartet Vocal Cords Up Close

I think this is very cool.  There are four singers (two female, two male) getting a video stroboscopy

I’m not sure of the piece they are singing, but they are in four parts: Soprano, Alto, Tenor, Bass.  That mean that they are all singing different notes.  The alto and bass are interesting to me. The alto especially seems like her conriculate, arytenoid, and cuneiform cartilage is working over time.  Usually in vocal production, the more open and relaxed the throat the less tension there is in the sound.  The difference between the soprano and alto is pretty dramatic.  It could be just the way the throat is formed or it could be technique or tension related.