Bowls that were capable of singing began to be imported to the West from around the early 1970s. The musicians Henry Wolff and Nancy Hennings have been credited with the singing bowl's introduction for musical purposes in their 1972 new-age album "Tibetan Bells" (although they gave no details of the bowls used in the recording). This was the first in what would become a series of five related releases: "Tibetan Bells II" (1978), "Yamantaka with Mickey Hart" (1982), "Tibetan Bells III" (1988), and "Tibetan Bells IV" (1991). The albums are based on the concept of taking a spiritual journey, with the music as a guide.