Bachmann Spectrum HO stuff has had Soundtraxx decoders for as long as they have offered sound. Bachmann just advertised on their website that they had sent their service techs to Soundtraxx for a training session. If they do sound in N, I would bet it would be Soundtraxx also as they have a good working relationship.
The HO decoders are stripped down versions of their over the counter stuff though, not sure if some would be happy with a bare bones sound decoders.
