diff --git a/audio/mp3/decode.go b/audio/mp3/decode.go
index 4d43d8b63..05c7a177c 100644
--- a/audio/mp3/decode.go
+++ b/audio/mp3/decode.go
@@ -87,6 +87,9 @@ func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
 //
 // A Stream doesn't close src even if src implements io.Closer.
 // Closing the source is src owner's responsibility.
+//
+// Resampling can be a very heavy task. Stream has a cache for resampling, but the size is limited.
+// Do not expect that Stream has a resampling cache even after whole data is played.
 func DecodeWithSampleRate(sampleRate int, src io.Reader) (*Stream, error) {
 	d, err := mp3.NewDecoder(src)
 	if err != nil {
diff --git a/audio/vorbis/vorbis.go b/audio/vorbis/vorbis.go
index 63cf13ee1..71381ab9d 100644
--- a/audio/vorbis/vorbis.go
+++ b/audio/vorbis/vorbis.go
@@ -182,6 +182,9 @@ func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
 //
 // A Stream doesn't close src even if src implements io.Closer.
 // Closing the source is src owner's responsibility.
+//
+// Resampling can be a very heavy task. Stream has a cache for resampling, but the size is limited.
+// Do not expect that Stream has a resampling cache even after whole data is played.
 func DecodeWithSampleRate(sampleRate int, src io.Reader) (*Stream, error) {
 	decoded, channelCount, origSampleRate, err := decode(src)
 	if err != nil {
diff --git a/audio/wav/decode.go b/audio/wav/decode.go
index 1dc0489b3..abd8593b7 100644
--- a/audio/wav/decode.go
+++ b/audio/wav/decode.go
@@ -134,6 +134,9 @@ func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
 //
 // A Stream doesn't close src even if src implements io.Closer.
 // Closing the source is src owner's responsibility.
+//
+// Resampling can be a very heavy task. Stream has a cache for resampling, but the size is limited.
+// Do not expect that Stream has a resampling cache even after whole data is played.
 func DecodeWithSampleRate(sampleRate int, src io.Reader) (*Stream, error) {
 	s, origSampleRate, err := decode(src)
 	if err != nil {