194 We also exhort you, Venerable Brethren, to promote with care congregational singing, and to see to its accurate execution with all due dignity, since it easily stirs up and arouses the faith and piety of large gatherings of the faithful. Let the full harmonious singing of our people rise to heaven like the bursting of a thunderous sea and let them testify by the melody of their song to the unity of their hearts and minds, as becomes brothers and the children of the same Father.
Source: Mediator Dei (Vatican.va)