What is the ruling on listening to a choir (vocal group) if it is devoid of musical instruments?

Forbidden singing is that which includes musical instruments, or whose lyrics contain a religious prohibition such as polytheism or an invitation to immorality, or that which causes temptation, such as men listening to women's voices, or that which distracts from the remembrance of Allah and the performance of religious duties.

As for natural, melodious sounds free of musical instruments, whose lyrics do not contain a religious prohibition, from which no temptation is feared, and which do not distract from the remembrance of Allah and the performance of religious duties, listening to them is not forbidden. An exception to this is anything that stirs lust, even if it does not involve melody.

Scholars have interpreted the hadiths that permit singing as referring to that which is free from anything that incites inclinations towards lust, such as the singing of travelers and camel drivers, and poems that do not contain anything that incites inclinations towards lust.