Delayed lateral sound can exceed direct sound by 10 dB before perceived equally loud

Evidence

The top curve is from the well-known work by Haas (1972) in which he asked his listeners to adjust the relative levels of the spatially separate images associated with the direct and reflected sounds until they appeared to be equally loud. This tells us that, in a sound-reinforced public address situation, it is possible to raise the level of delayed sound from a laterally positioned loudspeaker by as much as 10 dB above the direct sound before it is perceived as being as loud as the direct sound. It is important information in the context of professional audio, including sound mixing and processing, but it is irrelevant in the context of small-room acoustics. — Toole, Floyd E, Sound reproduction- the acoustics and…, 618

Categorization

• XREF: The Hass effect equal-loudness limit is a classic psychoacoustic datum relevant to sound reinforcement and mixing practice.