One of the main reasons why one loudspeaker feels fatiguing after 60 minutes while another still sounds relaxed after six hours is, imo relatively straightforward. The human brain must assemble acoustic information, as mixed by the sound engineer, into a coherent soundstage in fractions of a second. This soundstage includes the spatial arrangement of instruments, such as drums behind the singer, bass on the left, or backing vocals on the right. This reconstruction becomes increasingly difficult the more reflections occur from walls, ceilings, or floors.
The brain’s task is significantly easier when fewer reflections are present or – to return to the topic of horns – when the proportion of direct sound increases. Conventional loudspeakers typically have a direct sound share of about 2-3%, while electrostatic speakers achieve only around 0.6 to 1.5% under usual room conditions.
With a direct sound share of approximately 30% or more, as found in perfectly tuned horn loudspeaker desigs, the brain has less work to do in processing the soundstage. As a result, the listener perceives the sound as more pleasant, especially during extended listening sessions. This is one of the main reasons why people who have experienced a perfectly tuned horn loudspeaker system often describe its sound as having a unique sense of ease and clarity.
Of course, the reasons you mentioned are also entirely correct.“
