合唱, 独唱, and 斉唱: group singers, soloists, and listeners
Compare 合唱 and 斉唱 in group-singing examples with 独唱 as one person's solo. Track who sings and where the sound is heard without assuming different participants, fixed harmony rules, or an absent audience.
合唱: people singing together
合唱 (がっしょう) appears here with group singing. 「卒業式で全員が校歌を合唱しました。」 means “Everyone sang the school song together at graduation.” Everyone sang the school song at graduation. The sentence identifies the participants and their action without describing the arrangement of vocal parts or harmony.
「教室から子どもたちの明るい合唱が聞こえる。」 means “The children's bright chorus can be heard from the classroom.” The children's bright chorus can be heard coming from the classroom. The children are the singers. Hearing their chorus does not by itself make the listener a participant in that singing.
独唱: one singer and the place a solo is heard
独唱 (どくしょう) refers to a vocal solo. 「音楽会の最後に妹が独唱した。」 means “My younger sister sang a solo at the end of the concert.” The younger sister sang the solo at the end of the concert. One singer performing does not mean that the venue had no audience or that the singer was alone in the building.
「静かな独唱が広い会場に響いた。」 means “A quiet vocal solo echoed through the large venue.” The quiet solo echoed through a large venue. The location where it was heard is stated, but the sentence does not say that there were no listeners or no accompanist.
斉唱: overlap in the group-singing examples
斉唱 (せいしょう) also appears here with people singing together. 「式の最後に全員で校歌を斉唱した。」 means “Everyone sang the school song together at the end of the ceremony.” Everyone sang the school song at the end of the ceremony. Like the 合唱 school-song example, this describes all participants singing; the two words do not establish different sets of singers in these sentences.
「会場に参加者の力強い斉唱が響いた。」 means “The participants' vigorous singing echoed through the venue.” The participants' vigorous singing echoed through the venue. Read the group participants in the 合唱 and 斉唱 examples alongside the single soloist in the 独唱 example. These sentences do not establish mandatory distinctions in vocal parts, harmony, or pitch.
Do the school-song examples with 合唱 and 斉唱 prove that different people must be singing?
Show the answer and why
No. Both examples describe everyone singing the school song together. They can be compared with the younger sister's solo, but they do not establish mandatory differences in vocal parts or harmony.