async def METHOD_NAME(self, plugin_ctx, req):
    chunk = req.args.get('chunk', '')
    start = float(req.args.get('start', '0'))
    end = req.args.get('end', None)
    end = None if end is None else float(end)
    audio_path = await self._get_chunk_slice(
        plugin_ctx.current_corpus.corpname, chunk, start, end)
    if audio_path is None:
        plugin_ctx.set_not_found()
        return {}, None
    async with aiofiles.open(audio_path, 'rb') as f:
        file_size = await aiofiles.os.path.getsize(audio_path)
        headers = {
            'Content-Type': 'audio/mpeg',
            'Content-Length': f'{file_size}',
            'Accept-Ranges': 'none',
        }
        if req.headers.get('range'):
            headers['Content-Range'] = f'bytes 0-{file_size - 1}/{file_size - 1}'
        return headers, await f.read()