Room Acoustics. If the sounds are presented over loudspeakers in any room other than an anechoic chamber, the frequency characteristics of the room will be superimposed on the frequency characteristics of the loudspeaker and the sounds. Room resonances will then have an effect on the perceived sound. Additionally, if a jury evaluation is being conducted in which the subjects are physically located in different positions within the room, the room acoustics will affect the sound differently for each subject. No longer will all the subjects experience the exact same sound, thus, introducing a bias into the results. If it is necessary to conduct listening evaluations using loudspeakers, adherence to Sections 4.1 (Room size and shape), 4.2.1 (Reflections and reverberation), and 4.2.2 (Room modes) of the AES standard 1 is recommended. It is recommended that loudspeaker arrangement conform to AES20-1996 Section 5.2 (Loudspeaker locations) and location of listeners conform to AES20-1996 Section 5.4 (Listening locations).Ambient Noise. Control of ambient noise is essential for the proper administration of a subjective listening evaluation. Noise sources within the listening room can be due to: computer fans, fluorescent lighting, HVAC, etc. The influence of these sources can be minimized through the remote location or containment of computers in acoustic enclosures, incandescent lighting and HVAC baffles/sound treatment. High transmission loss into the room is desirable to minimize the influences of outside noise.Single value dB or dBA levels are generally inadequate in describing the ambient noise levels of indoor environments. ANSI S3.1 defines octave and one-third octave band noise levels for audiometric test rooms. 2 However, bands below 125 Hz are undefined and everyday sounds with energy below 125 Hz are commonly encountered. As a result, it is recommended that ambient noise levels should conform to NCB (noise criteria) 20 or better 3 which specifies allowable levels in the 16 to 8000 Hz octave bands.During jury evaluations, the station at which the subject is located should be free from influences from the other subjects. Many times partitions are placed between subjects to minimize interaction between subjects. When listening to low level sounds, subjects with colds or respiratory ailments can make it difficult for not only themselves but also adjacent subjects to hear the stimuli.Decor. The listening room should be a comfortable and inviting environment for the subject. The room should look natural as opposed to "high tech." The more clinical the room looks, the more apprehension and anxiety the subjects will experience. Neutral colors should be used for the walls and furniture. Comfortable chairs and headphones (if used) are essential to reducing distractions and keeping the subject focused on the task at hand. Moderate lighting should be used. Lighting which is too dim may reduce a subject's attention to the desired task, especially, during lengthy or monotonous listening evaluations.Air Circulation, Temperatur...

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