Add torchaudio backend installation step

README.md

@@ -44,6 +44,12 @@ First, make sure to build the latest version of transformers:
 pip install transformers>=4.49 peft torchaudio
 ```
 
+Install a `torchaudio` backend, such as:
+
+```shell
+pip install soundfile
+```
+
 Then run the code:
 ```python
 import torch