R’ Akiva Eiger (Yoreh Deah, siman 1) discuses birchas erusin by a chosson who is deaf, and how he should go about performing kiddusin, as such a chosson can’t simply listen to the berachah being recited by the mesader kiddushin. R’ Akiva Eiger suggests that perhaps birchas erusin isn’t an obligation specifically incumbent upon the chosson, therefore, even if he doesn’t hear it, it is okay.
The Sha’arei Zevulun (Inyonei Chuppah Ve’Kiddushin) based on this R’ Akiva Eiger and various other proofs, proves that birchas erusin is not the chosson’s obligation, therefore, we can’t bring any proof from pesukei dezimra. By pesukei dezimra which is the individual’s obligation, one must be careful not to interrupt, however, by birchas erusin which is not the chosson’s obligation, it doesn’t matter if there is an interruption.
