diff --git a/app/build.gradle b/app/build.gradle
index c17931d..564954f 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -21,7 +21,7 @@ android {
         minSdkVersion 23
         targetSdkVersion 26
         versionCode 1
-        versionName "0.8.0"
+        versionName "0.8.1"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
         // Enabling multidex support.
         multiDexEnabled true
diff --git a/app/src/main/java/com/chrhsmt/sisheng/FirstScreen.kt b/app/src/main/java/com/chrhsmt/sisheng/FirstScreen.kt
index 05e4e7f..37fd4f2 100644
--- a/app/src/main/java/com/chrhsmt/sisheng/FirstScreen.kt
+++ b/app/src/main/java/com/chrhsmt/sisheng/FirstScreen.kt
@@ -130,7 +130,7 @@ class FirstScreen : AppCompatActivity() {
 
     private fun setUpReadWriteExternalStorage() {
         val dir = ExternalMedia.getExternalDirectoryPath(this)
-        if (ExternalMedia.isExternalStorageWritable() && dir.canWrite()) {
+        if (ExternalMedia.isExternalStorageWritable() && dir != null && dir!!.canWrite()) {
             Toast.makeText(this, "SDカードへの書き込みが可能です", Toast.LENGTH_SHORT).show()
             Log.d(TAG, String.format("External media path: %s", dir.absoluteFile))
         } else {
diff --git a/app/src/main/java/com/chrhsmt/sisheng/Settings.kt b/app/src/main/java/com/chrhsmt/sisheng/Settings.kt
index f328def..de53b48 100644
--- a/app/src/main/java/com/chrhsmt/sisheng/Settings.kt
+++ b/app/src/main/java/com/chrhsmt/sisheng/Settings.kt
@@ -21,6 +21,8 @@ object Settings {
     var baseLogarithmForPoint: Int = 5
     // ポイント成功閾値
     var pointSuccessThreshold: Int = 80
+    // ノイズのバッファカウントの閾値
+    var freqNoizeCountThreashold: Int = 2
 
     // Raspberry pi
     var raspberrypiHost: String = ""
diff --git a/app/src/main/java/com/chrhsmt/sisheng/persistence/ExternalMedia.kt b/app/src/main/java/com/chrhsmt/sisheng/persistence/ExternalMedia.kt
index 4851ec9..54a0210 100644
--- a/app/src/main/java/com/chrhsmt/sisheng/persistence/ExternalMedia.kt
+++ b/app/src/main/java/com/chrhsmt/sisheng/persistence/ExternalMedia.kt
@@ -24,12 +24,16 @@ object ExternalMedia {
         return Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)
     }
 
-    fun getExternalDirectoryPath(context: Context): File {
+    fun getExternalDirectoryPath(context: Context): File? {
         val dirs = context.getExternalFilesDirs(android.os.Environment.DIRECTORY_MUSIC)
         if (dirs.size >= 2 && !dirs.last().mkdirs()) {
             Log.e(TAG, "Directory not created");
         }
-        this.saveDir = dirs.last()
-        return dirs.last()
+        if (dirs.size > 1) {
+            this.saveDir = dirs.last()
+            return dirs.last()
+        } else {
+            return null
+        }
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/chrhsmt/sisheng/point/PointCalculator.kt b/app/src/main/java/com/chrhsmt/sisheng/point/PointCalculator.kt
index f399b32..c3a659f 100644
--- a/app/src/main/java/com/chrhsmt/sisheng/point/PointCalculator.kt
+++ b/app/src/main/java/com/chrhsmt/sisheng/point/PointCalculator.kt
@@ -8,6 +8,7 @@ import de.qaware.chronix.distance.DistanceFunctionFactory
 import de.qaware.chronix.dtw.FastDTW
 import de.qaware.chronix.dtw.TimeWarpInfo
 import de.qaware.chronix.timeseries.MultivariateTimeSeries
+import java.util.*
 
 /**
  * Created by chihiro on 2017/10/10.
@@ -91,6 +92,50 @@ abstract class PointCalculator {
 
     }
 
+    /**
+     * Removing noises.
+     * @freqList List of frequency
+     */
+    fun removeNoises(freqList: MutableList<Float>) {
+
+        val noizeMaxLength = Settings.freqNoizeCountThreashold
+        val freqSize = freqList.size
+        val noizeIndexList: MutableList<Int> = arrayListOf()
+
+        // 反転したListのインスタンスでループ
+        freqList.reversed().forEachIndexed { index, fl ->
+            // 実Index
+            val realIndex = freqSize - 1 - index
+
+            if (fl > 0) {
+                // ノイズ発見、indexにする
+                noizeIndexList.add(realIndex)
+            }
+
+            if (noizeIndexList.size > noizeMaxLength) {
+                // ノイズ判定サイズを超えたものはノイズとみなさないのでクリアー
+                noizeIndexList.clear()
+            }
+
+            if (fl <= 0) {
+                // 無音
+                if (noizeIndexList.size <= noizeMaxLength) {
+                    noizeIndexList.forEach { i ->
+                        // 除去(後ろから)
+                        freqList.removeAt(i)
+                    }
+                }
+                noizeIndexList.clear()
+            }
+
+            if (realIndex == 0 && noizeIndexList.isNotEmpty()) {
+                noizeIndexList.forEach { i ->
+                    freqList.removeAt(i)
+                }
+            }
+        }
+    }
+
     fun calcDistance(analyzedFreqList: List<Float>, exampleFrequencies: List<Float>): TimeWarpInfo {
 
         // chronix.fastdtw
diff --git a/app/src/main/java/com/chrhsmt/sisheng/point/SimplePointCalculator.kt b/app/src/main/java/com/chrhsmt/sisheng/point/SimplePointCalculator.kt
index 1ee776e..84060c4 100644
--- a/app/src/main/java/com/chrhsmt/sisheng/point/SimplePointCalculator.kt
+++ b/app/src/main/java/com/chrhsmt/sisheng/point/SimplePointCalculator.kt
@@ -14,8 +14,13 @@ open class SimplePointCalculator : PointCalculator() {
     override fun calc(frequencies: MutableList<Float>, testFrequencies: MutableList<Float>): Point {
 
         var analyzedFreqList: MutableList<Float> = this.copy(frequencies)
+        // 調整(男女差)
         this.adjustFrequencies(analyzedFreqList)
 
+        // ノイズ除去
+        this.removeNoises(analyzedFreqList)
+
+        // 無音除去
         analyzedFreqList = this.removeLastSilence(analyzedFreqList)
         this.minimizeSilence(analyzedFreqList)
         val exampleFrequencies = this.removeLastSilence(testFrequencies)