DIFF Subgroup
H04R 1/323 Full Title
Details of transducers, > Arrangements for obtaining desired frequency or directional characteristics (for stereophonic purpose H04R5/00) > for obtaining desired directional characteristic only
H04R 1/323 Details of transducers, > Arrangements for obtaining desired frequency or directional characteristics (for stereophonic purpose H04R5/00) > for obtaining desired directional characteristic only