diff --git a/audioutils/fmsynth/fmsynth.c b/audioutils/fmsynth/fmsynth.c
index 86a791fab2..21b43bcf0e 100644
--- a/audioutils/fmsynth/fmsynth.c
+++ b/audioutils/fmsynth/fmsynth.c
@@ -107,6 +107,24 @@ int fmsynth_initialize(int fs)
   return fmsynthop_set_samplerate(fs);
 }
 
+/****************************************************************************
+ * name: create_fmsynthsnd
+ ****************************************************************************/
+
+FAR fmsynth_sound_t *create_fmsynthsnd(FAR fmsynth_sound_t *snd)
+{
+  if (snd)
+    {
+      snd->own_allocate = 0;
+      snd->phase_time = 0;
+      snd->volume = FMSYNTH_MAX_VOLUME;
+      snd->operators = NULL;
+      snd->next_sound = NULL;
+    }
+
+  return snd;
+}
+
 /****************************************************************************
  * name: fmsynthsnd_create
  ****************************************************************************/
@@ -115,12 +133,11 @@ FAR fmsynth_sound_t *fmsynthsnd_create(void)
 {
   FAR fmsynth_sound_t *ret;
   ret = (FAR fmsynth_sound_t *)malloc(sizeof(fmsynth_sound_t));
+
   if (ret)
     {
-      ret->phase_time = 0;
-      ret->volume = FMSYNTH_MAX_VOLUME;
-      ret->operators = NULL;
-      ret->next_sound = NULL;
+      create_fmsynthsnd(ret);
+      ret->own_allocate = 1;
     }
 
   return ret;
@@ -132,7 +149,7 @@ FAR fmsynth_sound_t *fmsynthsnd_create(void)
 
 void fmsynthsnd_delete(FAR fmsynth_sound_t *snd)
 {
-  if (snd != NULL)
+  if (snd != NULL && snd->own_allocate == 1)
     {
       free(snd);
     }
@@ -164,6 +181,20 @@ void fmsynthsnd_set_soundfreq(FAR fmsynth_sound_t *snd, float freq)
     }
 }
 
+/****************************************************************************
+ * name: fmsynthsnd_stop
+ ****************************************************************************/
+
+void fmsynthsnd_stop(FAR fmsynth_sound_t *snd)
+{
+  FAR fmsynth_op_t *op;
+
+  for (op = snd->operators; op != NULL; op = op->parallelop)
+    {
+      fmsynthop_stop(op);
+    }
+}
+
 /****************************************************************************
  * name: fmsynthsnd_set_volume
  ****************************************************************************/
diff --git a/audioutils/fmsynth/fmsynth_eg.c b/audioutils/fmsynth/fmsynth_eg.c
index 6f7ca48523..a2b97adedd 100644
--- a/audioutils/fmsynth/fmsynth_eg.c
+++ b/audioutils/fmsynth/fmsynth_eg.c
@@ -65,28 +65,38 @@ static int set_egparams(int fs,
  ****************************************************************************/
 
 /****************************************************************************
- * name: fmsyntheg_create
+ * name: create_fmsyntheg
  ****************************************************************************/
 
-FAR fmsynth_eg_t *fmsyntheg_create(void)
+FAR fmsynth_eg_t *create_fmsyntheg(FAR fmsynth_eg_t *eg)
 {
   int i;
-  FAR fmsynth_eg_t *ret = (FAR fmsynth_eg_t *)malloc(sizeof(fmsynth_eg_t));
 
-  if (ret)
+  if (eg)
     {
-      ret->state = EGSTATE_RELEASED;
-      ret->state_counter = 0;
+      eg->state = EGSTATE_RELEASED;
+      eg->state_counter = 0;
       for (i = 0; i < EGSTATE_MAX; i++)
         {
-          ret->state_params[i].initval = 0;
-          ret->state_params[i].period = 0;
+          eg->state_params[i].initval = 0;
+          eg->state_params[i].period = 0;
         }
 
-      ret->state_params[EGSTATE_RELEASED].initval = FMSYNTH_MAX_EGLEVEL;
+      eg->state_params[EGSTATE_RELEASED].initval = FMSYNTH_MAX_EGLEVEL;
     }
 
-  return ret;
+  return eg;
+}
+
+/****************************************************************************
+ * name: fmsyntheg_create
+ ****************************************************************************/
+
+FAR fmsynth_eg_t *fmsyntheg_create(void)
+{
+  FAR fmsynth_eg_t *ret = (FAR fmsynth_eg_t *)malloc(sizeof(fmsynth_eg_t));
+
+  return create_fmsyntheg(ret);
 }
 
 /****************************************************************************
diff --git a/audioutils/fmsynth/fmsynth_op.c b/audioutils/fmsynth/fmsynth_op.c
index 6bb200cd9c..bb07f12f74 100644
--- a/audioutils/fmsynth/fmsynth_op.c
+++ b/audioutils/fmsynth/fmsynth_op.c
@@ -248,6 +248,34 @@ int fmsynthop_set_samplerate(int fs)
   return OK;
 }
 
+/****************************************************************************
+ * name: create_fmsynthop
+ ****************************************************************************/
+
+FAR fmsynth_op_t *create_fmsynthop(FAR fmsynth_op_t *op,
+                                   FAR fmsynth_eg_t *eg)
+{
+  if (op)
+    {
+      op->eg = eg;
+
+      op->own_allocate  = 0;
+      op->wavegen       = NULL;
+      op->cascadeop     = NULL;
+      op->parallelop    = NULL;
+      op->feedback_ref  = NULL;
+      op->feedback_val  = 0;
+      op->feedbackrate  = 0;
+      op->last_sigval   = 0;
+      op->freq_rate     = 1.f;
+      op->sound_freq    = 0.f;
+      op->delta_phase   = 0.f;
+      op->current_phase = 0.f;
+    }
+
+  return op;
+}
+
 /****************************************************************************
  * name: fmsynthop_create
  ****************************************************************************/
@@ -267,17 +295,8 @@ FAR fmsynth_op_t *fmsynthop_create(void)
           return NULL;
         }
 
-      ret->wavegen       = NULL;
-      ret->cascadeop     = NULL;
-      ret->parallelop    = NULL;
-      ret->feedback_ref  = NULL;
-      ret->feedback_val  = 0;
-      ret->feedbackrate  = 0;
-      ret->last_sigval   = 0;
-      ret->freq_rate     = 1.f;
-      ret->sound_freq    = 0.f;
-      ret->delta_phase   = 0.f;
-      ret->current_phase = 0.f;
+      create_fmsynthop(ret, ret->eg);
+      ret->own_allocate = 1;
     }
 
   return ret;
@@ -289,11 +308,11 @@ FAR fmsynth_op_t *fmsynthop_create(void)
 
 void fmsynthop_delete(FAR fmsynth_op_t *op)
 {
-  if (op != NULL)
+  if (op != NULL && op->own_allocate == 1)
     {
       if (op->eg)
         {
-          free(op->eg);
+          fmsyntheg_delete(op->eg);
         }
 
       free(op);
@@ -499,12 +518,18 @@ void fmsynthop_stop(FAR fmsynth_op_t *op)
 
 int fmsynthop_operate(FAR fmsynth_op_t *op, int phase_time)
 {
+  int val;
+  int val2;
   int phase;
   FAR fmsynth_op_t *subop;
 
   op->current_phase = phase_time ? op->current_phase + op->delta_phase : 0.f;
 
-  phase = (int)op->current_phase + op->feedback_val;
+  val = (int)op->current_phase;
+  val2 = (val / (2 * FMSYNTH_PI));
+
+  phase = (int)val + op->feedback_val;
+  op->current_phase = op->current_phase - (float)(val2 * (2 * FMSYNTH_PI));
 
   subop = op->cascadeop;
 
diff --git a/include/audioutils/fmsynth.h b/include/audioutils/fmsynth.h
index 827be95df7..b5676a358d 100644
--- a/include/audioutils/fmsynth.h
+++ b/include/audioutils/fmsynth.h
@@ -43,6 +43,7 @@
 
 typedef struct fmsynth_sound_s
 {
+  int own_allocate;
   int phase_time;
   int max_phase_time;
   int volume;
@@ -64,6 +65,8 @@ extern "C"
 
 int fmsynth_initialize(int fs);
 FAR fmsynth_sound_t *fmsynthsnd_create(void);
+FAR fmsynth_sound_t *create_fmsynthsnd(FAR fmsynth_sound_t *);
+void fmsynthsnd_stop(FAR fmsynth_sound_t *snd);
 void fmsynthsnd_delete(FAR fmsynth_sound_t *snd);
 int fmsynthsnd_set_operator(FAR fmsynth_sound_t *snd, FAR fmsynth_op_t *op);
 void fmsynthsnd_set_soundfreq(FAR fmsynth_sound_t *snd, float freq);
diff --git a/include/audioutils/fmsynth_eg.h b/include/audioutils/fmsynth_eg.h
index 040cc7b98b..f69b42e495 100644
--- a/include/audioutils/fmsynth_eg.h
+++ b/include/audioutils/fmsynth_eg.h
@@ -85,6 +85,7 @@ extern "C"
 {
 #endif
 
+FAR fmsynth_eg_t *create_fmsyntheg(fmsynth_eg_t *eg);
 FAR fmsynth_eg_t *fmsyntheg_create(void);
 void fmsyntheg_delete(FAR fmsynth_eg_t *eg);
 int fmsyntheg_set_param(FAR fmsynth_eg_t *eg,
diff --git a/include/audioutils/fmsynth_op.h b/include/audioutils/fmsynth_op.h
index bbba432166..ec54ccf1ef 100644
--- a/include/audioutils/fmsynth_op.h
+++ b/include/audioutils/fmsynth_op.h
@@ -52,6 +52,7 @@ typedef struct fmsynth_op_s
   struct fmsynth_op_s *cascadeop;
   struct fmsynth_op_s *parallelop;
 
+  int own_allocate;
   FAR int *feedback_ref;
   int feedback_val;
   int feedbackrate;
@@ -75,6 +76,8 @@ extern "C"
 int fmsynthop_set_samplerate(int fs);
 
 FAR fmsynth_op_t *fmsynthop_create(void);
+FAR fmsynth_op_t *create_fmsynthop(FAR fmsynth_op_t *op,
+                                   FAR fmsynth_eg_t *eg);
 void fmsynthop_delete(FAR fmsynth_op_t *op);
 int fmsynthop_select_opfunc(FAR fmsynth_op_t *op, int type);
 int fmsynthop_set_envelope(FAR fmsynth_op_t *op,