Query: Who developed the Dynagroove format?
Context: These techniques, marketed, to name two, as the CBS DisComputer and Teldec Direct Metal Mastering, were used to reduce inner-groove distortion. RCA Victor introduced another system to reduce dynamic range and achieve a groove with less surface noise under the commercial name of Dynagroove. Two main elements were combined: another disk material with less surface noise in the groove and dynamic compression for masking background noise.