diff --git a/common/sound_api.h b/common/sound_api.h
new file mode 100644
index 00000000..dcb0956e
--- /dev/null
+++ b/common/sound_api.h
@@ -0,0 +1,67 @@
+/*
+sound_api.h - Xash3D extension for client sound interface
+Copyright (C) 2026
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+*/
+
+#ifndef SOUND_API_H
+#define SOUND_API_H
+
+#include "xash3d_types.h"
+
+#define CL_SOUND_INTERFACE_VERSION	1
+
+// sound handle (same as engine's sound_t)
+typedef int sound_t;
+
+struct dma_api_s;
+struct listener_s;
+
+// Forward decls (full def in engine/client/sound.h)
+struct channel_s;
+struct rawchan_s;
+struct portable_samplepair_s;
+
+// Engine-owned state: client reads only. Filled by engine, passed to pfnS_Init.
+typedef struct snd_interface_state_s
+{
+	const struct listener_s *listener;
+	const struct channel_s  *channels;        // &channels[0], contiguous
+	int                      total_channels;
+	struct rawchan_s *const *raw_channels;   // rawchan_t*[]
+	int                      max_raw_channels;
+} snd_interface_state_t;
+
+// API from engine to client (client calls these)
+typedef struct sound_api_s
+{
+	qboolean      (*CL_GetEntitySpatialization)( struct channel_s *ch );
+	struct sfx_s* (*S_GetSfxByHandle)( sound_t handle );
+} sound_api_t;
+
+// Callbacks from client to engine (engine calls these when custom sound is active)
+typedef struct sound_interface_s
+{
+	int version;
+
+	qboolean (*pfnS_Init)( snd_interface_state_t *state );
+	void     (*pfnS_Shutdown)( void );
+	void     (*pfnS_UpdateSound)( void );
+	/* Full paint: endtime (sample pairs), dma buffer, paintedtime in/out. Client does mix + transfer to dma.buffer. */
+	void     (*pfnS_PaintChannels)( int endtime, struct dma_api_s *dma, int *paintedtime );
+	void     (*pfnS_UpdateChannel)( int ch_idx, const struct channel_s *ch, sound_t handle );  // ch=NULL -> channel freed
+	void     (*pfnS_UpdateRawChannel)( int raw_idx, struct rawchan_s *ch );  // ch=NULL -> channel freed
+	void     (*pfnS_Spatialize)( struct channel_s *ch );
+	void     (*pfnS_FreeSound)( struct sfx_s *sfx, sound_t handle );
+} sound_interface_t;
+
+#endif // SOUND_API_H
diff --git a/engine/cdll_exp.h b/engine/cdll_exp.h
index 240d9c25..3751b7e1 100644
--- a/engine/cdll_exp.h
+++ b/engine/cdll_exp.h
@@ -23,6 +23,12 @@ struct mstudioevent_s;
 struct engine_studio_api_s;
 struct r_studio_interface_s;
 
+struct sound_api_s;
+struct sound_interface_s;
+
+typedef struct sound_api_s sound_api_t;
+typedef struct sound_interface_s sound_interface_t;
+
 // NOTE: ordering is important!
 typedef struct cldll_func_s
 {
@@ -74,6 +80,8 @@ typedef struct cldll_func_s
 	int (*pfnTouchEvent)( int type, int fingerID, float x, float y, float dx, float dy );
 	void (*pfnMoveEvent)( float forwardmove, float sidemove );
 	void (*pfnLookEvent)( float relyaw, float relpitch );
+	// Sound API
+	int (*pfnGetSoundInterface)( int version, sound_api_t *api, sound_interface_t *callback );
 } cldll_func_t;
 
 #endif//CDLL_EXP_H
diff --git a/engine/client/cl_game.c b/engine/client/cl_game.c
index 592b705c..c86faad0 100644
--- a/engine/client/cl_game.c
+++ b/engine/client/cl_game.c
@@ -92,6 +92,7 @@ static const dllfunc_t cdll_new_exports[] = 	// allowed only in SDK 2.3 and high
 { "HUD_VoiceStatus", (void **)&clgame.dllFuncs.pfnVoiceStatus },
 { "HUD_ChatInputPosition", (void **)&clgame.dllFuncs.pfnChatInputPosition },
 { "HUD_GetRenderInterface", (void **)&clgame.dllFuncs.pfnGetRenderInterface },	// Xash3D ext
+{ "HUD_GetSoundInterface", (void **)&clgame.dllFuncs.pfnGetSoundInterface },	// Xash3D ext
 { "HUD_ClipMoveToEntity", (void **)&clgame.dllFuncs.pfnClipMoveToEntity },	// Xash3D ext
 { "IN_ClientTouchEvent", (void **)&clgame.dllFuncs.pfnTouchEvent}, // Xash3D FWGS ext
 { "IN_ClientMoveEvent", (void **)&clgame.dllFuncs.pfnMoveEvent}, // Xash3D FWGS ext
diff --git a/engine/client/cl_main.c b/engine/client/cl_main.c
index 5c881008..3580bf4a 100644
--- a/engine/client/cl_main.c
+++ b/engine/client/cl_main.c
@@ -3678,8 +3678,6 @@ void CL_Init( void )
 	CL_InitLocal();
 
 	VID_Init();	// init video
-	S_Init();	// init sound
-	Voice_Init( VOICE_DEFAULT_CODEC, 3, true ); // init voice (do not open the device)
 
 	// unreliable buffer. unsed for unreliable commands and voice stream
 	MSG_Init( &cls.datagram, "cls.datagram", cls.datagram_buf, sizeof( cls.datagram_buf ));
@@ -3689,6 +3687,9 @@ void CL_Init( void )
 	if( !CL_LoadProgs( libpath ))
 		Host_Error( "can't initialize %s: %s\n", libpath, COM_GetLibraryError( ));
 
+	S_Init();	// init sound
+	Voice_Init( VOICE_DEFAULT_CODEC, 3, true ); // init voice (do not open the device)
+
 	ID_Init();
 	SteamBroker_Init();
 
diff --git a/engine/client/client.h b/engine/client/client.h
index 013edf37..ff8b861e 100644
--- a/engine/client/client.h
+++ b/engine/client/client.h
@@ -26,6 +26,7 @@ GNU General Public License for more details.
 #include "pm_defs.h"
 #include "ref_params.h"
 #include "render_api.h"
+#include "sound_api.h"
 #include "cdll_exp.h"
 #include "screenfade.h"
 #include "protocol.h"
@@ -449,6 +450,7 @@ typedef struct
 	void		*hInstance;		// pointer to client.dll
 	cldll_func_t	dllFuncs;			// dll exported funcs
 	render_interface_t	drawFuncs;		// custom renderer support
+	sound_interface_t	soundFuncs;		// custom sound support
 	poolhandle_t      mempool;			// client edicts pool
 	string		mapname;			// map name
 	string		maptitle;			// display map title
diff --git a/engine/client/s_load.c b/engine/client/s_load.c
index 4dbed9e3..0e094220 100644
--- a/engine/client/s_load.c
+++ b/engine/client/s_load.c
@@ -232,6 +232,11 @@ void S_FreeSound( sfx_t *sfx )
 		prev = &hashSfx->hashNext;
 	}
 
+	if( clgame.soundFuncs.pfnS_FreeSound ) {
+		clgame.soundFuncs.pfnS_FreeSound( sfx, sfx - s_knownSfx );
+		return;
+	}
+
 	if( sfx->cache )
 		FS_FreeSound( sfx->cache );
 	memset( sfx, 0, sizeof( *sfx ));
diff --git a/engine/client/s_main.c b/engine/client/s_main.c
index b2f0888c..3b6f1282 100644
--- a/engine/client/s_main.c
+++ b/engine/client/s_main.c
@@ -45,6 +45,9 @@ int          total_channels;
 int          soundtime;	// sample PAIRS
 int          paintedtime; 	// sample PAIRS
 
+static sound_api_t s_clientSoundAPI;
+static snd_interface_state_t s_sndState;
+
 static CVAR_DEFINE( s_volume, "volume", "0.7", FCVAR_ARCHIVE|FCVAR_FILTERABLE, "sound volume" );
 CVAR_DEFINE( s_musicvolume, "MP3Volume", "1.0", FCVAR_ARCHIVE|FCVAR_FILTERABLE, "background music volume" );
 static CVAR_DEFINE( s_mixahead, "_snd_mixahead", "0.12", FCVAR_FILTERABLE, "how much sound to mix ahead of time" );
@@ -161,6 +164,18 @@ static qboolean S_IsClient( int entnum )
 	return entnum == s_listener.entnum;
 }
 
+/*
+=================
+S_NotifyChannelUpdate
+=================
+*/
+static void S_NotifyChannelUpdate( int ch_idx, const channel_t *ch, sound_t handle )
+{
+	if( !clgame.soundFuncs.pfnS_UpdateChannel )
+		return;
+
+	clgame.soundFuncs.pfnS_UpdateChannel( ch_idx, ch, handle );
+}
 
 // free channel so that it may be allocated by the
 // next request to play a sound.  If sound is a
@@ -173,6 +188,10 @@ S_FreeChannel
 */
 void S_FreeChannel( channel_t *ch )
 {
+	int ch_idx = ch - channels;
+	if( ch_idx >= 0 && ch_idx < MAX_CHANNELS )
+		S_NotifyChannelUpdate( ch_idx, NULL, -1 );
+
 	ch->sfx = NULL;
 	ch->name[0] = '\0';
 	ch->use_loop = false;
@@ -184,6 +203,19 @@ void S_FreeChannel( channel_t *ch )
 	SND_CloseMouth( ch );
 }
 
+/*
+=================
+S_NotifyRawChannelUpdate
+=================
+*/
+static void S_NotifyRawChannelUpdate( int raw_idx, rawchan_t *ch )
+{
+	if( !clgame.soundFuncs.pfnS_UpdateRawChannel )
+		return;
+
+	clgame.soundFuncs.pfnS_UpdateRawChannel( raw_idx, ch );
+}
+
 /*
 =================
 S_UpdateSoundFade
@@ -543,6 +575,11 @@ SND_Spatialize
 */
 static void SND_Spatialize( channel_t *ch )
 {
+	if( clgame.soundFuncs.pfnS_Spatialize ) {
+		clgame.soundFuncs.pfnS_Spatialize( ch );
+		return;
+	}
+
 	// anything coming from the view entity will allways be full volume
 	if( S_IsClient( ch->entnum ))
 	{
@@ -704,6 +741,9 @@ void S_StartSound( const vec3_t pos, int ent, int chan, sound_t handle, float fv
 		}
 	}
 
+	ch_idx = target_chan - channels;
+	S_NotifyChannelUpdate( ch_idx, target_chan, handle );
+
 	// Init client entity mouth movement vars
 	SND_InitMouth( ent, chan );
 }
@@ -810,6 +850,8 @@ void S_RestoreSound( const vec3_t pos, int ent, int chan, sound_t handle, float
 	target_chan->sample = sample;
 	target_chan->forced_end = end;
 
+	S_NotifyChannelUpdate( target_chan - channels, target_chan, handle );
+
 	// Init client entity mouth movement vars
 	SND_InitMouth( ent, chan );
 }
@@ -898,6 +940,7 @@ void S_AmbientSound( const vec3_t pos, int ent, sound_t handle, float fvol, floa
 	ch->entchannel = CHAN_STATIC;
 	ch->basePitch = pitch;
 
+	S_NotifyChannelUpdate( ch - channels, ch, handle );
 	SND_Spatialize( ch );
 }
 
@@ -1161,6 +1204,8 @@ rawchan_t *S_FindRawChannel( int entnum, qboolean create )
 	ch->entnum = entnum;
 	ch->s_rawend = 0;
 
+	S_NotifyRawChannelUpdate( best, ch );
+
 	return ch;
 }
 
@@ -1513,7 +1558,11 @@ static void S_UpdateChannels( void )
 		endtime -= ( endtime - paintedtime ) & 0x3;
 	}
 
-	S_PaintChannels( endtime );
+	s_sndState.total_channels = total_channels;
+	if( clgame.soundFuncs.pfnS_PaintChannels )
+		clgame.soundFuncs.pfnS_PaintChannels( endtime, &dma, &paintedtime );
+	else
+		S_PaintChannels( endtime );
 
 	SNDDMA_Submit();
 }
@@ -1563,6 +1612,10 @@ void SND_UpdateSound( void )
 
 	if( !dma.initialized ) return;
 
+	if( clgame.soundFuncs.pfnS_UpdateSound ) {
+		clgame.soundFuncs.pfnS_UpdateSound();
+	}
+
 	// if the loading plaque is up, clear everything
 	// out to make sure we aren't looping a dirty
 	// dma buffer while loading
@@ -1917,6 +1970,33 @@ static void S_VoiceRecordStop_f( void )
 	Voice_RecordStop();
 }
 
+/*
+================
+S_FillSoundAPI
+================
+*/
+static void S_FillSoundAPI( sound_api_t *api )
+{
+	memset( api, 0, sizeof( *api ));
+	api->CL_GetEntitySpatialization = CL_GetEntitySpatialization;
+	api->S_GetSfxByHandle = S_GetSfxByHandle;
+}
+
+/*
+================
+S_FillSndState
+================
+*/
+static void S_FillSndState( snd_interface_state_t *st )
+{
+	memset( st, 0, sizeof( *st ));
+	st->listener = &s_listener;
+	st->channels = channels;
+	st->total_channels = total_channels;
+	st->raw_channels = raw_channels;
+	st->max_raw_channels = MAX_RAW_CHANNELS;
+}
+
 /*
 ================
 S_Init
@@ -1978,6 +2058,22 @@ qboolean S_Init( void )
 	S_InitSounds ();
 	VOX_Init ();
 
+	memset( &clgame.soundFuncs, 0, sizeof( clgame.soundFuncs ));
+
+	if( clgame.dllFuncs.pfnGetSoundInterface )
+	{
+		S_FillSoundAPI( &s_clientSoundAPI );
+		S_FillSndState( &s_sndState );
+
+		if( clgame.dllFuncs.pfnGetSoundInterface( CL_SOUND_INTERFACE_VERSION, &s_clientSoundAPI, &clgame.soundFuncs ))
+		{
+			if( clgame.soundFuncs.pfnS_Init && clgame.soundFuncs.pfnS_Init( &s_sndState ))
+			{
+				Con_Reportf( "%s: ^2initialized extended SoundAPI ^7ver. %i\n", __func__, CL_SOUND_INTERFACE_VERSION );
+			}
+		}
+	}
+
 	return true;
 }
 
@@ -2002,6 +2098,11 @@ void S_Shutdown( void )
 	Cmd_RemoveCommand( "speak" );
 	Cmd_RemoveCommand( "spk" );
 
+	if( clgame.soundFuncs.pfnS_Shutdown )
+	{
+		clgame.soundFuncs.pfnS_Shutdown();
+	}
+
 	S_StopAllSounds (false);
 	S_FreeRawChannels ();
 	S_FreeSounds ();
diff --git a/engine/client/sound.h b/engine/client/sound.h
index 47962b13..dea7fb5d 100644
--- a/engine/client/sound.h
+++ b/engine/client/sound.h
@@ -38,7 +38,7 @@ extern poolhandle_t sndpool;
 
 #define CLIP16( x ) bound( SHRT_MIN + 8, x, SHRT_MAX - 8 )
 
-typedef struct
+typedef struct portable_samplepair_s
 {
 	int left;
 	int right;
@@ -72,7 +72,7 @@ typedef struct snd_format_s
 	byte channels;
 } snd_format_t;
 
-typedef struct
+typedef struct dma_api_s
 {
 	snd_format_t format;
 	int          samples;     // mono samples in buffer