The relative influence of pitch and timbre on the apparent location of sound in the median sagittal plane

Listeners were requested to locate sounds originating in the median sagittal plane (MSP). The stimuli, 75-Msec pulses, were repeated at a rate of 200 times/sec and were filtered to transmit narrow bands centered about 0.63, 1.6, 2.5, or 6.3 kHz. Despite the sameness of pitch generated by all stimuli, Os perceived the 0.63-, 1.6-, and 2.5-kHz-centered sounds as originating low, middle, and high, respectively, in the MSP, regardless of their actual positions. The stimuli centered about 6.3 kHz, on the other hand, were located accurately by most Os. These findings were interpreted to mean that under conditions of inadequate auditory cues, timbre, not pitch, influences perceived elevation. The implication is that timbre also served as the cue for the apparent elevation of those sounds which, due to their high-frequency components, can be located accurately.     

The BUS-ALL: An inexpensive set of interface for the SKED system

A cost-effective relay-transistor interface has been developed for connecting the minicomputer with the experimental environment. The interface contains a 10-msec clock, input (response) channels, and output (stimulus channels.     

Relationships between college performance and success as an Army officer

This study investigated the relationships between both academic and nonacademic indices of college success and four indices of occupational success of Army officers. Subjects were 103 U.S. Military Academy graduates from the Class of 1962. Criteria were gathered 6 and 10 years after graduation, and multiple regression results indicated that three of the four criteria were significantly predicted. Results also showed that a leadership rating received the most weight in the equations, and that academic grades can contribute significantly to the prediction of officer success. Grades in physical education and tactics received nonsignificant weights in all but one case.     

The influence of stimulus bandwidth on localization of sound in space

The ability of listeners, deprived of prominent interaural time and intensity cues, to locate noise bands differing in width was investigated. To minimize binaural cues, we placed the sound source at various positions in the median sagittal plane. To eliminate binaural cues, we occluded one ear. The stimuli consisted of broadband noise and bands of noise centered at 8.0 kHz. The width of the latter ranged from 1.0 to 6.0 kHz. The results from seven listeners showed that localization proficiency for sounds in the median sagittal plane decreased with decreases in bandwidth for both binaural and monaural listening conditions. This function was less orderly for monaural localization of horizontally positioned sounds. Another consequence of a reduction in bandwidth was an increasing tendency of listeners to select certain loudspeakers over others as the source of the sound. A previous finding showing that localization of sound in the median sagittal plane is more accurate when listening binaurally rather than monaurally was confirmed.     

Are monocular arrays discriminable from binocular arrays?

On each trial of this experiment, a subject was visually stimulated by one or two shadows on a translucent background in a Telebinocular. For each subject, there were 40 trials of monocular stimulation by one shadow, 40 trials of monocular stimulation by two shadows (one in each hemifield), and 40 trials of binocular stimulation by two shadows (one in the left hemifield of one eye and another in the right hemifield of the other eye). Across these randomly ordered trials, 52 subjects were unable to discriminate two right-eye shadows from two left-eye shadows and were unable to discriminate two monocularly perceived shadows from two binocularly perceived shadows. Generally, subjects tended to misidentify right-hemifield shadows as right-eye shadows and tended to misidentify two-hemifield shadows as two-eye shadows.     

The spatial attributes of stimulus frequency and their role in monaural localization of sound in the horizontal plane

Listeners, whose right ears were blocked, located low-intensity sounds originating from loudspeakers placed 15 deg apart along the horizontal plane on the side of the open, or functioning, ear. In Experiment 1, the stimuli consisted of noise bursts, 1.0 kHz wide and centered at 4.0 through 14.0 kHz in steps of .5 kHz. We found that the apparent location of the noise bursts was governed by their frequency composition. Specifically, as the center frequency was increased from 4.0 to about 8.0 kHz, the sound appeared to move away from the frontal sector and toward the side. This migration pattern of the apparent sound source was observed again when the center frequency was increased from 8.0 to about 12.0 kHz. Then, with center frequencies of 13.0 and 14.0 kHz, the sound appeared once more in front. We referred to this relation between frequency composition and apparent location in terms of spatial referent maps. In Experiment 2, we showed that localization was more proficient if the frequency content of the stimulus served to connect adjacent spatial referent maps rather than falling within a single map. By these means, we have further elucidated the spectral cues utilized in monaural localization of sound in the horizontal plane.