diff --git a/doc/_notebooks/waveform.ipynb b/doc/_notebooks/waveform.ipynb
index 33a68e95b34974beec692dad67b896650e0f82fa..22d0b5202fd1f3d8a94959b331d52d4b33ce6a9d 100644
--- a/doc/_notebooks/waveform.ipynb
+++ b/doc/_notebooks/waveform.ipynb
@@ -503,7 +503,7 @@
    "source": [
     "Note that:\n",
     "\n",
-    "* sampling frequency: only a restricted set of sampling frequencies are allowed for input/output \n",
+    "* sampling frequency: only a restricted set of sampling frequencies are allowed for input/output (see set of supported frequencies `waveform.VALID_IO_FS`)\n",
     "* *dtype*: float/int data types are conserved when exporting a *Waveform*, since the .wav format allows many data types. However, many audio players only read .wav files coded with int16 values so you may not be able to listen to your exported sound with your favorite player. In that case, you may convert the data type of your *Waveform* using the optional *dtype* argument of method *to_wavfile*.\n",
     "* mask: the mask is lost when exporting to a .wav file.\n"
    ]
@@ -554,7 +554,7 @@
    "metadata": {},
    "source": [
     "### Integer-valued waveforms\n",
-    "Method *Waveform.astype* not only converts data types but also scale values to the range of the target type."
+    "Method *Waveform.astype* not only converts data types but also scale values to the range of the target type. The choice among the available integer types will result in different ranges. The following figures show integer-valued waveforms with different types: on the first row, waveforms created without conversion, from integer-valued data arrays where the full `dtype` range is used; on the second row, similar waveforms are created with a conversion from a float-valued array with entries in [-1, 1]."
    ]
   },
   {
@@ -605,7 +605,8 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Real-valued waveforms"
+    "### Real-valued waveforms\n",
+    "The choice among the available float types will not affect the range of the values but the precision. In the following example, one may observe how the floating-point precision varies, depending on the float type, when the fractionnal part is very small compared to the exponent part, which equals 1 here (see right column)."
    ]
   },
   {
@@ -623,14 +624,14 @@
     "w_float32 = Waveform(np.cos(2*np.pi*f0*t).astype(np.float32) + 1, fs=fs)\n",
     "w_float64 = Waveform(np.cos(2*np.pi*f0*t).astype(np.float64) + 1, fs=fs)\n",
     "\n",
-    "plt.figure(figsize=(20, 5))\n",
-    "plt.subplot(131)\n",
+    "plt.figure(figsize=(20, 15))\n",
+    "plt.subplot(321)\n",
     "plt.title('float16')\n",
     "w_float16.plot()\n",
-    "plt.subplot(132)\n",
+    "plt.subplot(323)\n",
     "plt.title('float32')\n",
     "w_float32.plot()\n",
-    "plt.subplot(133)\n",
+    "plt.subplot(325)\n",
     "plt.title('float64')\n",
     "w_float64.plot()\n",
     "\n",
@@ -643,16 +644,18 @@
     "w_float32 = Waveform(np.cos(2*np.pi*f0*t).astype(np.float32) * eps32 + 1, fs=fs)\n",
     "w_float64 = Waveform(np.cos(2*np.pi*f0*t).astype(np.float64) * eps64 + 1, fs=fs)\n",
     "\n",
-    "plt.figure(figsize=(20, 5))\n",
-    "plt.subplot(131)\n",
+    "plt.subplot(322)\n",
     "plt.title('float16')\n",
     "w_float16.plot()\n",
-    "plt.subplot(132)\n",
+    "plt.subplot(324)\n",
     "plt.title('float32')\n",
     "w_float32.plot()\n",
-    "plt.subplot(133)\n",
+    "plt.subplot(326)\n",
     "plt.title('float64')\n",
-    "w_float64.plot()\n"
+    "w_float64.plot()\n",
+    "plt.ylim(1 - 1.2 * eps64, 1 + 1.2 * eps64)\n",
+    "\n",
+    "pass"
    ]
   },
   {
@@ -729,6 +732,15 @@
     "w_float32.astype('uint8').plot()\n",
     "pass"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {
@@ -747,7 +759,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.5"
+   "version": "3.6.2"
   },
   "latex_envs": {
    "LaTeX_envs_menu_present": true,
diff --git a/madarrays/waveform.py b/madarrays/waveform.py
index 012822ea3766ec5a4dab4fbabe7614c57c04b0d8..e5bae27ee577ab46c782e5542d5652b436d533ca 100644
--- a/madarrays/waveform.py
+++ b/madarrays/waveform.py
@@ -405,6 +405,9 @@ class Waveform(MadArray):
         ------
         UserWarning
             If the signal is complex.
+        ValueError
+            If the sampling frequency is not supported (see set of supported
+            frequencies `waveform.VALID_IO_FS`).
         NotImplementedError
             If dtype is not supported by the current implementation.
 
@@ -549,7 +552,14 @@ class Waveform(MadArray):
             self[-len(w):] *= w[-1::-1]
 
     def show_player(self):
-        """Show the player when using jupyter notebook."""
+        """
+        Show the player when using jupyter notebook.
+
+        Raises
+        ------
+        ValueError
+            If sampling frequency is 1.
+        """
         try:
             from IPython.display import Audio
             if self.fs == 1:
@@ -577,6 +587,11 @@ class Waveform(MadArray):
         -------
         `simpleaudio.PlayObject`
             Object useful to handle the played audio stream.
+
+        Raises
+        ------
+        ValueError
+            If sampling frequency is 1.
         """
 
         if self.fs == 1: