Page 14 - Jul2009

Fig. 4. A participant seated in the listener station of the Dome Room. The dense population of the loudspeakers in this room allows for precise measurement of auditory localization.
can be positioned in the space between the foam wedges and the array to increase reflectivity and reverberation time. This will enable research studies examining the effects of systematic increases in the number of reflective surfaces and a room’s over- all reverberation time on auditory localization performance.
The ART has previously conducted research in auditory localization as it applies to military personnel. Investigations have included evaluations of the effects of hearing protection on the ability to accurately identify the location of a sound3–5 and localization of sounds in the presence of background noise.6,7 The Dome Room will allow for further evaluations of auditory perception of both stationary and moving sounds.
from 4.5 to 21 m in front of the listen- er. Three tracks create parallel lanes that run the length of the hall. Each track can be populated with up to 12 rows of up to 5 loudspeakers each along the length of the hall. The mounting bars are adjustable in height from 1.2 to 3 m above the floor so that sounds can be presented at the level with the listener’s ear, as well as at lev- els either above or below. Loudspeaker mounting bars can be positioned in horizontal, vertical or diagonal orien- tations relative to the listener and the mounting bars are interchangeable with those installed on the vertical arcs in the Dome Room.
The configuration of the lighting in the Distance Hall differs from that available in the other indoor research spaces. In the Distance Hall, there are 6 independent lighting controls in rows beginning at the position of the
listener. It is possible to extinguish all lighting except for a dim light above the listener location such that the listener is not able to perceive the size of the research space. This light- ing scenario would allow for exploration of the perception of sound source distances that are farther away than the physi- cally present loudspeakers through modifications of the spectral components of the sounds presented to the listener.
The Distance Hall will enable the ART to perform research in the areas of distance estimation and distance per- ception, as well as the effects of loudspeaker-to-listener dis- tance on a person’s ability to accurately identify the location of a sound source. There is a clear distinction between the
Distance Hall
The Distance Hall (Fig. 5) was named for its rectangular shape and intended research purpose. It meas- ures 21.3 m long by 5.6 m wide and is 3.7 m high. The acoustic configura- tion and audio capabilities permit investigation of auditory localization and tracking of sound sources mov- ing in a predetermined manner toward and away from the listener, auditory distance and depth estima- tion, tracking of sound sources mov- ing above the listener, and detection and recognition of sound sources appearing at moderate distances from the listener. The Distance Hall can contain up to 180 loudspeakers. These loudspeakers can be mounted to bars with the capacity to hold five loudspeakers each, suspended from the ceiling by brackets every 1.6 m
Fig. 5. A soldier sits in the listener position in the Distance Hall. The lighting in this room can be configured to hide the true size of the room.
The Environment for Auditory Research 13