One afternoon in the summer of 1995, a curious incident occurred. I was fine-tuning my spoken commentary on a CD I was preparing about music and the brain. To detect glitches in the recording, I was looping phrases so that I could hear them over and over. At one point, when I was alone in the room, I put one of the phrases, “sometimes behave so strangely,” on a loop, began working on something else and forgot about it. Suddenly it seemed to me that a strange woman was singing! After glancing around and finding nobody there, I realized that I was hearing my own voice repetitively producing this phrase—but now, instead of hearing speech, I perceived a melody spilling out of the loudspeaker. My speech had morphed into song by the simple process of repetition.
This striking perceptual transformation, which I later found occurs for most people, shows that the boundary between speech and song can be very fragile. Composers have taken account of the strong connections between music and speech, for example, incorporating spoken words and phrases into their compositions. In addition, numerous vocalizations seem to fall near the boundary between speech and song, including religious chants and incantations, oratory, opera recitative (a style of delivery in opera resembling sung ordinary speech), the cries of street vendors and some rap music.