import json


def metric_names(metadata_fname):
    """Return an alphabetically sorted list of the evaluated scales."""
    with open(metadata_fname, 'r') as f:
        metadata = json.load(f)
    sound_name_list = sorted(metadata.keys())
    eval_name_list = sorted(metadata[sound_name_list[0]]['evaluations'].keys())
    return eval_name_list