The international standard DF target curve rates worse than alternatives

Evidence

Much has been learned over the past decade about the perception and measurement of headphone sound quality. One lesson learned is that DF target 521. recommended in the current international standards is consistently rated lower in sound quality than alternative targets. It might be time for the headphone standards to catch up with modern science. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1871

Categorization

• QUESTION: Which exactly is DF target 521 and does it differ from 514 and 713 in documented perceptual underpinnings?
• SEED: The proposition that official standards lag scientific evidence is worth an essay on how diffusion-field targets entrenched before in-room preference data arrived.