diff --git a/lib_com/options.h b/lib_com/options.h
index 10396a5c34071df32d355449d6e62d8717e547a8..d65d8932893bcaa942f772ab6b6d5b5838aa7f3e 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -108,6 +108,7 @@
 #define FIX_2283_ISM_MD_DELAY                           /* Dolby: Fix ISM metadata delay round-off */
 #define FIX_2283_Q_CLDFB                                /* FhG: Fix Q format issue in CLDFB */
 #define FIX_2283_ACCU_CLDFB                             /* FhG: Fix to consider Q-format differences in accumulateCLDFBArrayToBuffer_fx() */
+#define FIX_FLOAT_1518                                  /* FhG: fix issue 1518: loudness differences in OSBA decoding to mono or stereo output */
 
 /* ##################### End NON-BE switches ########################### */
 
diff --git a/lib_dec/ivas_cpe_dec_fx.c b/lib_dec/ivas_cpe_dec_fx.c
index 45007974483505fb416b1075b6e00456be83df21..25928f6ffdf232c30ece923800f8c70af2d0c586 100644
--- a/lib_dec/ivas_cpe_dec_fx.c
+++ b/lib_dec/ivas_cpe_dec_fx.c
@@ -663,7 +663,15 @@ ivas_error ivas_cpe_dec_fx(
     test();
     IF( EQ_16( hCPE->element_mode, IVAS_CPE_MDCT ) && EQ_16( hCPE->nchan_out, 1 ) && ( is_DTXrate( ivas_total_brate ) == 0 || ( EQ_16( is_DTXrate( ivas_total_brate ), 1 ) && is_DTXrate( st_ivas->hDecoderConfig->last_ivas_total_brate ) == 0 ) ) )
     {
-        applyDmxMdctStereo_fx( hCPE, output, output_frame );
+#ifdef FIX_FLOAT_1518
+        test();
+        IF( !( EQ_16( st_ivas->ivas_format, SBA_ISM_FORMAT ) && EQ_16( st_ivas->ism_mode, ISM_MODE_NONE ) ) )
+        {
+#endif
+            applyDmxMdctStereo_fx( hCPE, output, output_frame );
+#ifdef FIX_FLOAT_1518
+        }
+#endif
     }
 
     /*----------------------------------------------------------------*
diff --git a/lib_dec/ivas_dec_fx.c b/lib_dec/ivas_dec_fx.c
index bd3eab3e4feb8c9131b76321da996b6d835e91f4..d95c010c8eaf7be6fa17e7b68ca97d14c267c636 100644
--- a/lib_dec/ivas_dec_fx.c
+++ b/lib_dec/ivas_dec_fx.c
@@ -574,6 +574,12 @@ ivas_error ivas_dec_fx(
 
             ivas_sba_dirac_stereo_dec_fx( st_ivas, &p_output_fx[sba_ch_idx], output_frame );
         }
+#ifdef FIX_FLOAT_1518
+        ELSE IF( EQ_16( st_ivas->hDecoderConfig->nchan_out, 1 ) && EQ_16( st_ivas->ism_mode, ISM_MODE_NONE ) )
+        {
+            v_shr( p_output_fx[0], -1, p_output_fx[0], output_frame );
+        }
+#endif
 
         /* HP filtering */
         FOR( n = 0; n < getNumChanSynthesis( st_ivas ); n++ )
diff --git a/lib_dec/ivas_sba_dirac_stereo_dec_fx.c b/lib_dec/ivas_sba_dirac_stereo_dec_fx.c
index 0f18a6eab2a1fd0b39eb0bded7cfc7f5d1580e29..502550d3b4dab987a4ad8a6ac957e2c928259ada 100644
--- a/lib_dec/ivas_sba_dirac_stereo_dec_fx.c
+++ b/lib_dec/ivas_sba_dirac_stereo_dec_fx.c
@@ -1502,7 +1502,12 @@ void ivas_sba_dirac_stereo_dec_fx(
     synchro_synthesis_fx( st_ivas->hDecoderConfig->ivas_total_brate, hCPE, output, output_frame, 1 /*st_ivas->sba_dirac_stereo_flag*/, q_dft[0] );
 
     /* output scaling */
+#ifdef FIX_FLOAT_1518
+    test();
+    IF( !sba_mono_flag && !( EQ_16( st_ivas->ivas_format, SBA_ISM_FORMAT ) && EQ_16( st_ivas->ism_mode, ISM_MODE_NONE ) ) )
+#else
     IF( !sba_mono_flag )
+#endif
     {
         v_shr( output[0], 1, output[0], output_frame ); /*0.5f*/
         v_shr( output[1], 1, output[1], output_frame ); /*0.5f*/
diff --git a/lib_dec/ivas_stereo_mdct_core_dec_fx.c b/lib_dec/ivas_stereo_mdct_core_dec_fx.c
index 8df5a33faf571f9672c4a544f314d51cd86dba07..2b4e575960551168324d36eebd1d2863afd92437 100644
--- a/lib_dec/ivas_stereo_mdct_core_dec_fx.c
+++ b/lib_dec/ivas_stereo_mdct_core_dec_fx.c
@@ -464,7 +464,13 @@ void stereo_mdct_core_dec_fx(
     test();
     test();
     test();
+
+#ifdef FIX_FLOAT_1518
+    test();
+    IF( hCPE->nchan_out == 1 && ( bfi == 0 || ( bfi != 0 && sts[0]->core != ACELP_CORE && sts[1]->core != ACELP_CORE ) ) && !( EQ_16( st_ivas->ivas_format, SBA_ISM_FORMAT ) && EQ_16( st_ivas->ism_mode, ISM_MODE_NONE ) ) )
+#else
     IF( hCPE->nchan_out == 1 && ( bfi == 0 || ( bfi != 0 && sts[0]->core != ACELP_CORE && sts[1]->core != ACELP_CORE ) ) )
+#endif
     {
         apply_dmx_weights_fx( hCPE, x_fx, sts[0]->transform_type, sts[1]->transform_type );
     }