diff --git a/src/net/torvald/terrarum/audio/AudioMixer.kt b/src/net/torvald/terrarum/audio/AudioMixer.kt
index aa957e860..0d929b670 100644
--- a/src/net/torvald/terrarum/audio/AudioMixer.kt
+++ b/src/net/torvald/terrarum/audio/AudioMixer.kt
@@ -20,6 +20,11 @@ import kotlin.math.*
  * Created by minjaesong on 2023-11-07.
  */
 object AudioMixer: Disposable {
+    var SPEED_OF_SOUND = 340f
+
+    const val SPEED_OF_SOUND_AIR = 340f
+    const val SPEED_OF_SOUND_WATER = 1480f
+
     const val DEFAULT_FADEOUT_LEN = 1.8
 
     val masterVolume: Double
diff --git a/src/net/torvald/terrarum/audio/TerrarumAudioFilter.kt b/src/net/torvald/terrarum/audio/TerrarumAudioFilter.kt
index 2633d7ade..7f0b27195 100644
--- a/src/net/torvald/terrarum/audio/TerrarumAudioFilter.kt
+++ b/src/net/torvald/terrarum/audio/TerrarumAudioFilter.kt
@@ -2,6 +2,7 @@ package net.torvald.terrarum.audio
 
 import com.jme3.math.FastMath
 import com.jme3.math.FastMath.sin
+import net.torvald.terrarum.audio.AudioMixer.SPEED_OF_SOUND
 import net.torvald.terrarum.audio.TerrarumAudioMixerTrack.Companion.BUFFER_SIZE
 import net.torvald.terrarum.audio.TerrarumAudioMixerTrack.Companion.SAMPLING_RATEF
 import kotlin.math.absoluteValue
@@ -187,7 +188,7 @@ object Buffer : TerrarumAudioFilter() {
  * @param soundSpeed speed of the sound in meters per seconds
  * @param earDist distance between ears in meters
  */
-class BinoPan(var pan: Float, var soundSpeed: Float = 340f, var earDist: Float = 0.18f): TerrarumAudioFilter() {
+class BinoPan(var pan: Float, var earDist: Float = 0.18f): TerrarumAudioFilter() {
 
     private val PANNING_CONST = 3.0 // 3dB panning rule
 
@@ -203,7 +204,7 @@ class BinoPan(var pan: Float, var soundSpeed: Float = 340f, var earDist: Float =
     override fun thru(inbuf0: List<FloatArray>, inbuf1: List<FloatArray>, outbuf0: List<FloatArray>, outbuf1: List<FloatArray>
     ) {
         val angle = pan * 1.5707963f
-        val timeDiffMax = earDist / soundSpeed * SAMPLING_RATEF
+        val timeDiffMax = earDist / SPEED_OF_SOUND * SAMPLING_RATEF
         val delayInSamples = (timeDiffMax * sin(angle)).absoluteValue
         val volMultDbThis = PANNING_CONST * pan.absoluteValue
         val volMultFsThis = decibelsToFullscale(volMultDbThis).toFloat()
diff --git a/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt b/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
index febf29c8c..3b0918283 100644
--- a/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
+++ b/src/net/torvald/terrarum/ui/BasicDebugInfoWindow.kt
@@ -621,7 +621,7 @@ class BasicDebugInfoWindow : UICanvas() {
                 else "R${filter.pan.absoluteValue.times(100).toIntAndFrac(3,1)}"
                 App.fontSmallNumbers.draw(batch, panLabel, x+3f, y+1f)
 
-                App.fontSmallNumbers.draw(batch, "AS:${filter.soundSpeed.roundToInt()}", x+3f, y+17f)
+                App.fontSmallNumbers.draw(batch, "AS:${AudioMixer.SPEED_OF_SOUND.roundToInt()}", x+3f, y+17f)
             }
             is Buffer -> {
                 batch.color = FILTER_NAME_ACTIVE