Audio dataset is not decoding on 4.1.1
Previously (datasets<=3.6.0), audio columns were decoded automatically when accessing a row. Now, for performance reasons, audio decoding is lazy by default: you just see the file path unless you explicitly cast the column to Audio.

Here’s the fix (following the current [datasets audio docs](https://huggingface.co/docs/datasets/en/audio_load)
):

```
from datasets import load_dataset, Audio

dataset = load_dataset("MrDragonFox/Elise", split="train")

# Explicitly decode the audio column
dataset = dataset.cast_column("audio", Audio(sampling_rate=16_000))

print(dataset[0]["audio"])
# {'path': '...', 'array': array([...], dtype=float32), 'sampling_rate': 16000}
``` @haitam03-yo's comment is right that the data is not decoded by default anymore indeed, but here is how it works in practice now:

From `datasets` v4, audio data are read as [AudioDecoder](https://meta-pytorch.org/torchcodec/0.4/generated/torchcodec.decoders.AudioDecoder.html) objects from torchcodec. This doesn't decode the data by default, but you can call `audio.get_all_samples()` to decode the audio.

See the documentation on how to process audio data here: https://huggingface.co/docs/datasets/audio_process To resolve this, you need to explicitly cast the audio column to the Audio feature. This will decode the audio data and make it accessible as an array. Here is the corrected code snippet


from datasets import load_dataset, Audio

# Load your dataset
dataset = load_dataset("MrDragonFox/Elise", split="train")

# Explicitly cast the 'audio' column to the Audio feature
dataset = dataset.cast_column("audio", Audio(sampling_rate=16_000))

# Now you can access the decoded audio array
print(dataset[0]["audio"])

By adding the cast_column step, you are telling the datasets library to decode the audio data with the specified sampling rate, and you will then be able to access the audio array as you were used to in previous versions.
### Describe the bug

The audio column remain as non-decoded objects even when accessing them.

```python
dataset = load_dataset("MrDragonFox/Elise", split = "train")
dataset[0] # see that it doesn't show 'array' etc...
```

Works fine with `datasets==3.6.0`

Followed the docs in 

- https://huggingface.co/docs/datasets/en/audio_load

### Steps to reproduce the bug

```python
dataset = load_dataset("MrDragonFox/Elise", split = "train")
dataset[0] # see that it doesn't show 'array' etc...
```


### Expected behavior

It should decode when accessing the elemenet

### Environment info

4.1.1
ubuntu 22.04


Related

- https://github.com/huggingface/datasets/issues/7707