Normalized with a ref signal mean&std and restored using the same values, is there a energy gap between ref and separated signals?

[yangxueruivs]

❓ Questions

in https://github.com/facebookresearch/demucs/blob/v4.0.1/demucs/separate.py#L176:
ref = wav.mean(0)
wav -= ref.mean()
wav /= ref.std()
sources = apply_model(model, wav[None], device=args.device, shifts=args.shifts,
split=args.split, overlap=args.overlap, progress=True,
num_workers=args.jobs, segment=args.segment)[0]
sources *= ref.std()
sources += ref.mean()

source signal has an energy gap from the ref signal. Can we directly apply the mean and variance to the separated sources?