diff --git a/aucat/aucat.c b/aucat/aucat.c
index 87fc27a..caab35b 100644
--- a/aucat/aucat.c
+++ b/aucat/aucat.c
@@ -346,6 +346,10 @@ slot_init(struct slot *s)
 			enc_init(&s->conv, &s->afile.par, slot_nch);
 			s->convbuf =
 			    xmalloc(s->round * slot_nch * sizeof(adata_t));
+			enc_sil_do(&s->conv, s->buf.data, bufsz);
+		} else {
+			memset(s->buf.data, 0,
+			    bufsz * slot_nch * sizeof(adata_t));
 		}
 	}
 	s->pstate = SLOT_INIT;
diff --git a/sndiod/dev.c b/sndiod/dev.c
index ef85a83..4905eae 100644
--- a/sndiod/dev.c
+++ b/sndiod/dev.c
@@ -1710,6 +1710,10 @@ slot_attach(struct slot *s)
 			enc_init(&s->sub.enc, &s->par, slot_nch);
 			s->sub.encbuf =
 			    xmalloc(s->round * slot_nch * sizeof(adata_t));
+			enc_sil_do(&s->sub.enc, s->sub.buf.data, s->appbufsz);
+		} else {
+			memset(s->sub.buf.data, 0,
+			    s->appbufsz * slot_nch * sizeof(adata_t));
 		}
 
 		/*