diff --git a/pizzactrl/fs_names.py b/pizzactrl/fs_names.py
index ddd593d..6cfbf7c 100644
--- a/pizzactrl/fs_names.py
+++ b/pizzactrl/fs_names.py
@@ -80,12 +80,12 @@ class StoryFile(FileHandle):
         FileHandle.__init__(self, name, FileType.STORY)
 
 
-REC_NAME = RecFile('name.mp3')
-REC_MY_IBK = RecFile('my_ibk.mp3')
+REC_NAME = RecFile('name.wav')
+REC_MY_IBK = RecFile('my_ibk.wav')
 REC_PORTRAIT = RecFile('portrait.jpg')
-REC_CITY_NAME = RecFile('city_name.mp3')
-REC_CITY_DESC = RecFile('city_description.mp3')
-REC_CITY_SOUND = RecFile('city_sound.mp3')
+REC_CITY_NAME = RecFile('city_name.wav')
+REC_CITY_DESC = RecFile('city_description.wav')
+REC_CITY_SOUND = RecFile('city_sound.wav')
 REC_DRAW_CITY = RecFile('city_video.h264')
 REC_CITY_PHOTO = RecFile('city_drawing.jpg')
 REC_MERGED_VIDEO = RecFile('video.mp4')
diff --git a/pizzactrl/hal_serial.py b/pizzactrl/hal_serial.py
index 7480f2c..5da4e1b 100644
--- a/pizzactrl/hal_serial.py
+++ b/pizzactrl/hal_serial.py
@@ -5,11 +5,9 @@ from enum import Enum
 
 from typing import Any, List
 from scipy.io.wavfile import write as writewav
-import pydub
 
 import sounddevice as sd
 import soundfile as sf
-import numpy as np
 
 from . import gpio_pins