with_fx :reverb, mix: 0.2 do
  loop do
    play scale(:Eb2, :major_pentatonic, num_octaves: 3).choose, release: 0.1, amp: rand
    sleep 0.1
  end
end

Link: https://sonic-pi-gallery.s3.amazonaws.com/37e3859d1981b2b25b4fd248f27c3427.wav