What is the ruling on listening to sheilat that contain modified voices to make them melodious?

If modified voices or "sheilat" produce sounds similar to musical instruments, then they take the ruling of prohibition. However, if they are distinct from the sounds of musical instruments, they remain on the principle of permissibility. So, if sheilat consist of chanting and melodies with the voices of chanters without musical instruments, there is no harm in them if they are in what is permissible. But if they are vocal rhythms that are manipulated to become like sounds emanating from musical instruments, then they take the ruling of music, and listening to them is forbidden.