For this study, reported in two JASA Express Letters [1,2], we created six simulated concert halls that have same monaural room acoustical parameter values according to ISO3382-1. The simulated early reflections are seen in the figure below. Examples of sound samples can be found on the supplementary video.

The first letter [1] that wideband early reflections that preserve the temporal envelope of sound contribute to the clear and open acoustics with strong bass. Such reflections are fused with the direct sound due to the precedence effect. In contrast, reflections that distort the temporal envelope render the sound weak and muddy because they partially break down the precedence. Moreover, the reflected sound has to reach the listener from another direction than the direct sound for open and enveloping sound.

The second letter [2] explains why lateral early reflections were shown to contribute to the perceived distance, envelopment, and openness. Our explanation is that lateral reflections are beneficial due to their increasing effect on binaural loudness—the phenomenon known well in psychoacoustics, but not in architectural acoustics. The reflections from the side are amplified more than median plane reflections, in particular at high frequencies, due to the shape of the human head.

References

@article{lok11jasael,
	author = {T. Lokki and J. P{\"a}tynen and S. Tervo and S. Siltanen and L. Savioja},
	date-added = "2012-04-28 15:23:43 +0300",
	date-modified = "2013-02-04 10:57:05 +0200",
	journal = "Journal of the Acoustical Society of America",
	month = "June",
	number = 6,
	pages = "EL223-EL228",
	title = "Temporal envelope preserving reflections surrounding the listener make engaging acoustics",
	url = "http://dx.doi.org/10.1121/1.3579145",
	volume = 129,
	year = 2011,
	bdsk-url-1 = "http://dx.doi.org/10.1121/1.3579145"
}

@article{lok11jasael2,
	author = {T. Lokki and J. P{\"a}tynen},
	date-added = "2013-04-29 16:32:16 +0300",
	date-modified = "2013-04-29 16:32:16 +0300",
	journal = "Journal of the Acoustical Society of America",
	keywords = "Concert hall acoustics",
	month = "November",
	number = 5,
	pages = "EL345-EL351",
	title = "Lateral reflections are favorable in concert halls due to binaural loudness",
	url = "http://dx.doi.org/10.1121/1.3647866",
	volume = 130,
	year = 2011,
	bdsk-url-1 = "http://dx.doi.org/10.1121/1.3647866"
}