Haas measured how much louder a delayed sound could be before dominating localization

Evidence

But Haas moved even farther from passive acoustical realities and deliberately amplified the delayed sound, as would happen in a professional audio sound reinforcement situation. It is not a facsimile of any possible single reflection. His interest was to determine how much higher in sound level the delayed sound could be before it became the dominant localization cue (i.e. subjectively louder). To do this he asked his listeners to adjust the sound level of the delayed loudspeaker until both of the perceived images appeared to be equally loud. This is the balance point, beyond which the delayed loudspeaker would be perceived as being dominant. — Toole, Floyd E, Sound reproduction- the acoustics and…, 605