diff --git a/parakeet/data/batch.py b/parakeet/data/batch.py
index 515074d1..5e7ac399 100644
--- a/parakeet/data/batch.py
+++ b/parakeet/data/batch.py
@@ -53,8 +53,8 @@ def batch_text_id(minibatch, pad_id=0, dtype=np.int64):
     peek_example = minibatch[0]
     assert len(peek_example.shape) == 1, "text example is an 1D tensor"
 
-    lengths = [example.shape[0] for example in minibatch
-               ]  # assume (channel, n_samples) or (n_samples, )
+    lengths = [example.shape[0] for example in
+               minibatch]  # assume (channel, n_samples) or (n_samples, )
     max_len = np.max(lengths)
 
     batch = []
diff --git a/parakeet/exps/tacotron2/ljspeech.py b/parakeet/exps/tacotron2/ljspeech.py
index 20dc29d3..59c855eb 100644
--- a/parakeet/exps/tacotron2/ljspeech.py
+++ b/parakeet/exps/tacotron2/ljspeech.py
@@ -67,19 +67,16 @@ class LJSpeechCollector(object):
 
         # Sort by text_len in descending order
         texts = [
-            i
-            for i, _ in sorted(
+            i for i, _ in sorted(
                 zip(texts, text_lens), key=lambda x: x[1], reverse=True)
         ]
         mels = [
-            i
-            for i, _ in sorted(
+            i for i, _ in sorted(
                 zip(mels, text_lens), key=lambda x: x[1], reverse=True)
         ]
 
         mel_lens = [
-            i
-            for i, _ in sorted(
+            i for i, _ in sorted(
                 zip(mel_lens, text_lens), key=lambda x: x[1], reverse=True)
         ]
 
diff --git a/tools/Makefile b/tools/Makefile
index 87107a53..e2aba8fe 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -24,7 +24,7 @@ clean:
 
 apt.done:
 	apt update -y
-	apt install -y bc flac jq vim tig tree pkg-config libflac-dev libogg-dev libvorbis-dev libboost-dev swig python3-dev 
+	apt install -y bc flac jq vim tig tree pkg-config libsndfile1 libflac-dev libogg-dev libvorbis-dev libboost-dev swig python3-dev 
 	echo "check_certificate = off" >> ~/.wgetrc
 	touch apt.done
 
diff --git a/tools/extras/README.md b/tools/extras/README.md
index 19c06a13..7d03c4be 100644
--- a/tools/extras/README.md
+++ b/tools/extras/README.md
@@ -1,3 +1,7 @@
+# install scripts
+call from `tools` dir.
+
+## Details
 1. kaldi
 
 deps gcc, mkl or openblas
diff --git a/tools/extras/install_soundfile.sh b/tools/extras/install_soundfile.sh
new file mode 100755
index 00000000..cbc4e00d
--- /dev/null
+++ b/tools/extras/install_soundfile.sh
@@ -0,0 +1,18 @@
+# install package libsndfile
+
+WGET=wget --no-check-certificate
+
+SOUNDFILE=libsndfile-1.0.28
+SOUNDFILE_LIB=${SOUNDFILE}tar.gz
+
+echo "Install package libsndfile into default system path."
+test -e ${SOUNDFILE_LIB} || ${WGET} -c "http://www.mega-nerd.com/libsndfile/files/${SOUNDFILE_LIB}"
+if [ $? != 0 ]; then
+    echo "Download ${SOUNDFILE_LIB} failed !!!"
+    exit 1
+fi
+
+tar -zxvf ${SOUNDFILE_LIB}
+pushd ${SOUNDFILE}
+./configure > /dev/null && make > /dev/null && make install > /dev/null
+popd
\ No newline at end of file