diff --git a/TODO b/TODO
index ea24989..0ca716f 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,4 @@
 Basic:
-* Correct tone length calculation
-* Settings
-
 * Koch lesson select
 * Run a koch lesson
 * Koch result analysis screen
@@ -12,6 +9,8 @@ Polish:
 * Visual styling
 * Settings info text
 * Extract UI strings into resource file
+* Play sample sounds when settings change
+* More Settings
 
 Bonus:
 * Morse machine
diff --git a/app/src/main/java/com/example/ecwt/DitDahGenerator.kt b/app/src/main/java/com/example/ecwt/DitDahGenerator.kt
index 1064380..6be08b1 100644
--- a/app/src/main/java/com/example/ecwt/DitDahGenerator.kt
+++ b/app/src/main/java/com/example/ecwt/DitDahGenerator.kt
@@ -6,9 +6,9 @@ import android.media.AudioTrack
 import android.media.MediaDataSource
 import android.view.KeyEvent
 import java.util.concurrent.ArrayBlockingQueue
-import java.util.concurrent.BlockingQueue
 import kotlin.concurrent.thread
 import kotlin.math.PI
+import kotlin.math.min
 import kotlin.math.sin
 
 enum class SoundTypes {
@@ -23,44 +23,44 @@ fun StringToSoundSequence(s : String) : List<SoundTypes> {
 
     val first = when(s[0]) {
         ' ' -> listOf(SoundTypes.WORD_SPACE)
-        'A' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE) 
-        'B' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE) 
-        'C' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'D' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'E' -> listOf(SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'F' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'G' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'H' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'I' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'J' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'K' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'L' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'M' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'N' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'O' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'P' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'Q' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'R' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'S' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        'T' -> listOf(SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'U' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'V' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'W' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'X' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'Y' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        'Z' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '0' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '1' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '2' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '3' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '4' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '5' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '6' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '7' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '8' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '9' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.WORD_SPACE)
-        '.' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.WORD_SPACE)
-        '?' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.WORD_SPACE)
+        'A' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'B' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'C' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'D' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'E' -> listOf(SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'F' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'G' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'H' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'I' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'J' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'K' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'L' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'M' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'N' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'O' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'P' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'Q' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'R' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'S' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        'T' -> listOf(SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'U' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'V' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'W' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'X' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'Y' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        'Z' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '0' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '1' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '2' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '3' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '4' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '5' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '6' -> listOf(SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '7' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '8' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '9' -> listOf(SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
+        '.' -> listOf(SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.LETTER_SPACE)
+        '?' -> listOf(SoundTypes.DIT, SoundTypes.DIT, SoundTypes.DAH, SoundTypes.DAH, SoundTypes.DIT, SoundTypes.DIT, SoundTypes.LETTER_SPACE)
         else -> { listOf() }
     }
 
@@ -113,60 +113,42 @@ fun KeycodeToSoundSequence(keycode : Int) : List<SoundTypes> {
 
 }
 
-
-class DitDahGenerator : MediaDataSource {
-    constructor() : super()
-
-    override fun close() {
-    }
-    override fun getSize() : Long {
-        return 80000;
-    }
-
-    override fun readAt(position: Long, buffer: ByteArray?, offset: Int, size: Int): Int {
-        if(position > 10000000)
-            return -1;
-/*
-        for(i in 0..size) {
-            val xt = sin((i + offset) / 44e3f) * 255.0f;
-            buffer?.set(i + offset, xt.toByte());
-        }
-*/
-        return size;
-    }
-
-}
-
 class DitDahGeneratorSettings
 {
-    var toneFrequency = 650 //TODO These values are duplicated in the settings fragment
-    var WordsPerMinute = 20;
+    //TODO These values are duplicated in the settings fragment
+    var toneFrequency = 650
+    var wordsPerMinute = 20
+    var farnsworthWordsPerMinute = 20
 }
 
 class DitDahSoundStream {
     constructor(config : DitDahGeneratorSettings) {
         // Farnsworth timing calculations: https://morsecode.world/international/timing.html
-        //TODO: Compute these properly
-        val ditLengthSeconds = 0.15f;
-        val dahLengthSeconds = ditLengthSeconds * 3.0f;
 
-        val ditLengthInSamples = (ditLengthSeconds * mAudioSampleRate).toInt();
-        val dahLengthInSamples = (dahLengthSeconds * mAudioSampleRate).toInt();
-        val interCharacterSpacingInSamples = ditLengthInSamples;
+        val t_dit = 60.0f / (50.0f * config.wordsPerMinute)
+        val t_fdit = ((60.0f / min(config.farnsworthWordsPerMinute, config.wordsPerMinute)) - 31.0f * t_dit) / 19.0f
 
-        mDitSound = ShortArray(ditLengthInSamples + interCharacterSpacingInSamples);
-        mDahSound = ShortArray(dahLengthInSamples + interCharacterSpacingInSamples);
-        mWordSpacingSound = ShortArray((dahLengthSeconds * mAudioSampleRate).toInt());
-        mCharacterSpacingSound = ShortArray((ditLengthSeconds * mAudioSampleRate).toInt());
+        val ditLengthInSamples = (t_dit * mAudioSampleRate).toInt()
+        val dahLengthInSamples = (t_dit * 3 * mAudioSampleRate).toInt()
+        val intraCharacterSpacingInSamples = (t_dit * mAudioSampleRate).toInt()
+        val interCharacterSpacingInSamples = (3 * t_fdit * mAudioSampleRate).toInt()
+        val wordSpacingInSamples = (7 * t_fdit * mAudioSampleRate).toInt()
+
+        mDitSound = ShortArray(ditLengthInSamples + intraCharacterSpacingInSamples)
+        mDahSound = ShortArray(dahLengthInSamples + intraCharacterSpacingInSamples)
+
+        // These two subtract the intra-character spacing, because they'll already have been played by the most recent sound
+        mWordSpacingSound = ShortArray(wordSpacingInSamples - intraCharacterSpacingInSamples);
+        mCharacterSpacingSound = ShortArray(interCharacterSpacingInSamples - intraCharacterSpacingInSamples);
 
         //TODO: Ramp up? Make sound nicer? Seems to have clipping - just in the emulator?
         val invSampleRate = 1.0 / mAudioSampleRate.toFloat()
         for(i in 0 until ditLengthInSamples) {
-            mDitSound[i] = (0x7fff.toFloat() * sin( 2.0f * PI * i * config.toneFrequency * invSampleRate)).toShort();
+            mDitSound[i] = (0x7fff.toFloat() * sin( 2.0f * PI * i * config.toneFrequency * invSampleRate)).toShort()
         }
 
         for(i in 0 until dahLengthInSamples) {
-            mDahSound[i] = (0x7fff.toFloat() * sin(2.0f * PI * i * config.toneFrequency * invSampleRate) ).toShort();
+            mDahSound[i] = (0x7fff.toFloat() * sin(2.0f * PI * i * config.toneFrequency * invSampleRate) ).toShort()
         }
 
         thread() { makeSoundsWorkerThreadFunc() }
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 3c6b394..ac50a58 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -14,11 +14,11 @@
         android:orientation="vertical">
 
         <Button
-            android:id="@+id/Sounder"
+            android:id="@+id/sounder"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:onClick="openSounder"
-            android:text="Button" />
+            android:text="Sounder" />
 
         <Button
             android:id="@+id/button2"