diff --git a/exp/audio/internal/driver/driver_openal.go b/exp/audio/internal/driver/driver_openal.go
index 2edff16ac..a359d300e 100644
--- a/exp/audio/internal/driver/driver_openal.go
+++ b/exp/audio/internal/driver/driver_openal.go
@@ -34,21 +34,37 @@ type Player struct {
 	source     io.Reader
 	sampleRate int
 	isClosed   bool
+	alFormat   uint32
+}
+
+func alFormat(channelNum, bytesPerSample int) uint32 {
+	switch {
+	case channelNum == 1 && bytesPerSample == 1:
+		return al.FormatMono8
+	case channelNum == 1 && bytesPerSample == 2:
+		return al.FormatMono16
+	case channelNum == 2 && bytesPerSample == 1:
+		return al.FormatStereo8
+	case channelNum == 2 && bytesPerSample == 2:
+		return al.FormatStereo16
+	}
+	panic(fmt.Sprintf("driver: invalid channel num (%d) or bytes per sample (%d)", channelNum, bytesPerSample))
 }
 
 func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Player, error) {
 	if e := al.OpenDevice(); e != nil {
-		return nil, fmt.Errorf("audio: OpenAL initialization failed: %v", e)
+		return nil, fmt.Errorf("driver: OpenAL initialization failed: %v", e)
 	}
 	s := al.GenSources(1)
 	if err := al.Error(); err != 0 {
-		return nil, fmt.Errorf("audio: al.GenSources error: %d", err)
+		return nil, fmt.Errorf("driver: al.GenSources error: %d", err)
 	}
 	p := &Player{
 		alSource:   s[0],
 		alBuffers:  []al.Buffer{},
 		source:     src,
 		sampleRate: sampleRate,
+		alFormat:   alFormat(channelNum, bytesPerSample),
 	}
 	runtime.SetFinalizer(p, (*Player).Close)
 
@@ -56,7 +72,7 @@ func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Play
 	emptyBytes := make([]byte, bufferSize)
 	for _, b := range bs {
 		// Note that the third argument of only the first buffer is used.
-		b.BufferData(al.FormatStereo16, emptyBytes, int32(p.sampleRate))
+		b.BufferData(p.alFormat, emptyBytes, int32(p.sampleRate))
 		p.alSource.QueueBuffers(b)
 	}
 	al.PlaySources(p.alSource)
@@ -74,14 +90,14 @@ var (
 
 func (p *Player) Proceed() error {
 	if err := al.Error(); err != 0 {
-		return fmt.Errorf("audio: before proceed: %d", err)
+		return fmt.Errorf("driver: before proceed: %d", err)
 	}
 	processedNum := p.alSource.BuffersProcessed()
 	if 0 < processedNum {
 		bufs := tmpAlBuffers[:processedNum]
 		p.alSource.UnqueueBuffers(bufs...)
 		if err := al.Error(); err != 0 {
-			return fmt.Errorf("audio: Unqueue in process: %d", err)
+			return fmt.Errorf("driver: Unqueue in process: %d", err)
 		}
 		p.alBuffers = append(p.alBuffers, bufs...)
 	}
@@ -91,10 +107,10 @@ func (p *Player) Proceed() error {
 		if 0 < n {
 			buf := p.alBuffers[0]
 			p.alBuffers = p.alBuffers[1:]
-			buf.BufferData(al.FormatStereo16, tmpBuffer[:n], int32(p.sampleRate))
+			buf.BufferData(p.alFormat, tmpBuffer[:n], int32(p.sampleRate))
 			p.alSource.QueueBuffers(buf)
 			if err := al.Error(); err != 0 {
-				return fmt.Errorf("audio: Queue in process: %d", err)
+				return fmt.Errorf("driver: Queue in process: %d", err)
 			}
 		}
 		if err != nil {
@@ -106,7 +122,7 @@ func (p *Player) Proceed() error {
 		al.RewindSources(p.alSource)
 		al.PlaySources(p.alSource)
 		if err := al.Error(); err != 0 {
-			return fmt.Errorf("audio: PlaySource in process: %d", err)
+			return fmt.Errorf("driver: PlaySource in process: %d", err)
 		}
 	}
 
@@ -115,7 +131,7 @@ func (p *Player) Proceed() error {
 
 func (p *Player) Close() error {
 	if err := al.Error(); err != 0 {
-		return fmt.Errorf("audio: error before closing: %d", err)
+		return fmt.Errorf("driver: error before closing: %d", err)
 	}
 	if p.isClosed {
 		return nil
@@ -130,7 +146,7 @@ func (p *Player) Close() error {
 	}
 	p.isClosed = true
 	if err := al.Error(); err != 0 {
-		return fmt.Errorf("audio: error after closing: %d", err)
+		return fmt.Errorf("driver: error after closing: %d", err)
 	}
 	runtime.SetFinalizer(p, nil)
 	return nil