diff --git a/android/app/src/main/java/com/tsmobile/app/voice/VoiceService.kt b/android/app/src/main/java/com/tsmobile/app/voice/VoiceService.kt
index 068af3e..8aa3662 100644
--- a/android/app/src/main/java/com/tsmobile/app/voice/VoiceService.kt
+++ b/android/app/src/main/java/com/tsmobile/app/voice/VoiceService.kt
@@ -55,6 +55,7 @@ class VoiceService(
     private var playbackGeneration = 0L
     private var activePlaybackTrack: AudioTrack? = null
     @Volatile private var receiveVolume = 1.0f
+    @Volatile private var receiveGain = 2.5f
 
     private val audioManager = context.getSystemService(AudioManager::class.java)
     private var audioFocusRequest: AudioFocusRequest? = null
@@ -129,6 +130,11 @@ class VoiceService(
         }
     }
 
+    /** 设置 PCM 预增益（1.0 = 原始音量，2.5 = 默认） */
+    fun setReceiveGain(gain: Float) {
+        receiveGain = gain.coerceIn(0.5f, 5.0f)
+    }
+
     fun enableReceivePlayback() {
         if (speakerEnabled) forceLoudspeaker()
     }
@@ -176,10 +182,12 @@ class VoiceService(
                     synchronized(playbackLock) { activePlaybackTrack = track }
                 }
                 val activeTrack = track ?: continue
+                // 应用 PCM 预增益
+                val gainedFrame = applyPcmGain(frame, receiveGain)
                 if (acceptedFrames <= 5 || acceptedFrames % 250L == 0L) {
-                    Log.i(TAG, "Writing mixed PCM bytes=${frame.size} trackState=${activeTrack.state} playState=${activeTrack.playState}")
+                    Log.i(TAG, "Writing mixed PCM bytes=${gainedFrame.size} gain=$receiveGain trackState=${activeTrack.state}")
                 }
-                val written = activeTrack.write(frame, 0, frame.size, AudioTrack.WRITE_BLOCKING)
+                val written = activeTrack.write(gainedFrame, 0, gainedFrame.size, AudioTrack.WRITE_BLOCKING)
                 if (written != frame.size) {
                     trackWriteFailures++
                     Log.w(TAG, "AudioTrack.write incomplete: $written/${frame.size}")
@@ -341,4 +349,21 @@ class VoiceService(
         selfSpeakingJob?.cancel(); selfSpeakingJob = null
         Log.d(TAG, "VoiceService destroyed")
     }
+
+    /**
+     * 对 PCM16 字节数组应用增益，clamp 到 int16 范围防止溢出。
+     * PCM 格式：小端序 interleaved stereo。
+     */
+    private fun applyPcmGain(pcm: ByteArray, gain: Float): ByteArray {
+        if (gain == 1.0f) return pcm
+        val result = pcm.copyOf()
+        for (i in result.indices step 2) {
+            // 小端序：低字节在前
+            val sample = ((result[i + 1].toInt() shl 8) or (result[i].toInt() and 0xFF)).toShort()
+            val gained = (sample.toFloat() * gain).toInt().coerceIn(Short.MIN_VALUE.toInt(), Short.MAX_VALUE.toInt())
+            result[i] = (gained and 0xFF).toByte()
+            result[i + 1] = (gained shr 8).toByte()
+        }
+        return result
+    }
 }