Fixed hierachy

Author: spors

filter_design/audiofilter.ipynb

@@ -1151,15 +1151,15 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Excursus: Higher Order Filters\n",
+    "### Excursus: Higher Order Filters\n",
     "\n",
     "In audio signal processing also IIR filters of higher order are applied. However, they will be usually split into second order sections for series or parallel connection. Note that the group delay of an IIR filter increases with higher filter order. \n",
     "\n",
     "\n",
     "\n",
     "A prominent example of using higher order IIR filters is found in loudspeaker engineering. For a multi-way loudspeaker each driver must only be driven within an appropriate intended frequency range. This is usually realized with a bandpass filter that is built from a series connection of a higher order lowpass and a higher order highpass filter. Thus, each loudspeaker exhibits its own bandpass filter. The acoustic summation of all the driver's generated sound pressures then yields the desired full audio bandwidth in the sonic domain.\n",
     "\n",
-    "### Linkwitz-Riley Crossover\n",
+    "#### Linkwitz-Riley Crossover\n",
     "\n",
     "Consider the following two driver application, in which the same bandpass characteristic is used for the low (LF) and high (HF) frequency driver. A special and often used case is achieved, when **two equal** 2nd-order **Butterworth** high-/low-pass filters **in series** built a 4th-order so called **[Linkwitz-Riley](http://www.linkwitzlab.com/crossovers.htm)** high-/low-pass filter."
    ]
@@ -1215,7 +1215,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Exercise\n",
+    "#### Exercise\n",
     "\n",
     "* What filter characteristic has the acoustic sum? To explore it in detail, plot and discuss the phase of the Linwitz-Riley filters as well as of the acoustic sum.\n",
     "\n",
@@ -1230,14 +1230,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Appendix"
+    "### Appendix"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Butterworth Filter Characteristics\n",
+    "#### Butterworth Filter Characteristics\n",
     "\n",
     "Higher order filter design can be realized with series connection of biquads. The coefficients for **Butterworth** type are e.g. given as, cf. \\cite{Tietze1978} \n",
     "\n",
@@ -1270,7 +1270,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Zoelzer PEQ (Type II, no Q prewarp)\n",
+    "#### Zoelzer PEQ (Type II, no Q prewarp)\n",
     "We check type of \\cite[Table 2.4]{Zoelzer2011} # U. Zoelzer (2011): \"DAFX - Digital Audio Effects\", 2nd, Wiley, Table 2.4:"
    ]
   },
@@ -1293,7 +1293,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### RBJ PEQ (Type III, Q prewarp: sin)\n",
+    "#### RBJ PEQ (Type III, Q prewarp: sin)\n",
     "We check type \\cite(Bristow-Johnson1994), eq. (16)\n",
     "\n",
     "Robert Bristow-Johnson (1994): \"The equivalence of various methods of\n",
@@ -1320,7 +1320,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Zoelzer 2nd Order Low-Shelving (Type I, Qz=Qp=1/sqrt(2))\n",
+    "#### Zoelzer 2nd Order Low-Shelving (Type I, Qz=Qp=1/sqrt(2))\n",
     "We check type of \\cite[Table 2.3]{Zoelzer2011} # U. Zoelzer (2011): \"DAFX - Digital Audio Effects\", 2nd, Wiley, Table 2.3:"
    ]
   },
@@ -1342,7 +1342,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### RBJ 2nd Order Low-Shelving (Type III, Qz=Qp=1/sqrt(2) -> S = 1)\n",
+    "#### RBJ 2nd Order Low-Shelving (Type III, Qz=Qp=1/sqrt(2) -> S = 1)\n",
     "We check type of Robert Bristow-Johnson [Audio EQ Cookbook](http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt)"
    ]
   },
@@ -1365,7 +1365,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Zoelzer 2nd Order High-Shelving (Type I, Qz=Qp=1/sqrt(2))\n",
+    "#### Zoelzer 2nd Order High-Shelving (Type I, Qz=Qp=1/sqrt(2))\n",
     "We check type of \\cite[Table 2.3]{Zoelzer2011} # U. Zoelzer (2011): \"DAFX - Digital Audio Effects\", 2nd, Wiley, Table 2.3:"
    ]
   },
@@ -1387,7 +1387,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### RBJ 2nd Order High-Shelving (Type III, Qz=Qp=1/sqrt(2) -> S = 1)\n",
+    "#### RBJ 2nd Order High-Shelving (Type III, Qz=Qp=1/sqrt(2) -> S = 1)\n",
     "We check type of Robert Bristow-Johnson [Audio EQ Cookbook](http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt)"
    ]
   },
@@ -1410,7 +1410,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## References\n",
+    "### References\n",
     "\n",
     "Please see the [biblio.bib](biblio.bib) for the cited references."
    ]

index.ipynb

@@ -20,7 +20,19 @@
     }
    },
    "source": [
-    "# 1. [Introduction](introduction/introduction.ipynb)"
+    "# 1. Introduction"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "nbsphinx-toctree": {
+     "maxdepth": 3,
+     "numbered": true
+    }
+   },
+   "source": [
+    "* [Introduction](introduction/introduction.ipynb)"
    ]
   },
   {