diff --git a/nemu/src/device/audio.c b/nemu/src/device/audio.c
index 8a43506..c63b02b 100644
--- a/nemu/src/device/audio.c
+++ b/nemu/src/device/audio.c
@@ -43,7 +43,7 @@ static void audio_callback(void *userdata, uint8_t *stream, int len) {
   uint32_t read_cnt = MIN(count, len);
   uint32_t to_end_cnt = CONFIG_SB_SIZE - pos_read;
   int32_t out_bound_cnt = read_cnt - to_end_cnt;
-  memset(stream, 0, len);
+  // memset(stream, 0, len);
   if (out_bound_cnt > 0) {
     memcpy(stream, sbuf + pos_read, to_end_cnt);
     memcpy(stream + to_end_cnt, sbuf, out_bound_cnt);
@@ -52,7 +52,7 @@ static void audio_callback(void *userdata, uint8_t *stream, int len) {
   }
   pos_read += read_cnt;
   pos_read %= CONFIG_SB_SIZE;
-  // if (len > read_cnt) memset(stream + read_cnt, 0, len - read_cnt);
+  if (len > read_cnt) memset(stream + read_cnt, 0, len - read_cnt);
   count -= read_cnt;
   audio_count = count;
   mtx_unlock(&mtx_audio);