メッセージを読み上げるdiscordbotがwavを再生しない

前提

見様見真似でDiscordのチャット読み上げbotを作ったを参考に(というかをそのまま)テキストチャンネルのメッセージをボイスチャンネルで再生してほしいのですが、wavは生成されてる(多分)のにエラーが出てしまいます

発生している問題・エラーメッセージ

---on_message_start---
<discord.voice_client.VoiceClient object at 0x000001AFC1056100>
#message.content:あ
C:/open_jtalk/bin/open_jtalk -x C:/open_jtalk/bin/dic -m C:/open_jtalk/bin/mei/mei_normal.htsvoice -r 1.0 -ow output.wav input.txt
Ignoring exception in on_message
Traceback (most recent call last):
  File "C:\Users\hi610\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\discord\client.py", line 343, in _run_event
    await coro(*args, **kwargs)
  File "c:\open_jtalk\bin\zatudanbot.py", line 66, in on_message
    source = discord.FFmpegPCMAudio("output.wav")
  File "C:\Users\hi610\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\discord\player.py", line 225, in __init__
    super().__init__(source, executable=executable, args=args, **subprocess_kwargs)
  File "C:\Users\hi610\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\discord\player.py", line 138, in __init__
    self._process = self._spawn_process(args, **kwargs)
  File "C:\Users\hi610\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\discord\player.py", line 147, in _spawn_process
    raise ClientException(executable + ' was not found.') from None
discord.errors.ClientException: ffmpeg was not found.

該当のソースコード

python
1if message.guild.voice_client:
2            print('#message.content:'+ message.content)
3            creat_WAV(message.content)
4            source = discord.FFmpegPCMAudio("output.wav")
5            message.guild.voice_client.play(source)