RESUMEN
This study assessed the effects of spatialized sound presentation on a listener's ability to monitor target (T) messages in the presence of competing (C) messages and high-level (110 dB[A]) background noise (BGN). In a simulated military environment, 8 participants wore two-channel, active noise reduction (ANR) equipped helmets and listened to combinations of T and C messages (89 dB[A] at the ear). T messages were presented synchronously with 0, 1, 2, and 3 C messages in four listening modes: (a) BGN + diotic, (b) BGN + dichotic, (c) BGN + spatial audio, and (d) quiet + spatial audio. Best overall performance occurred in the spatialized modes (c and d) and poorest in the diotic mode (a). As expected, speech recognition was better in quiet than in BGN when multiple C messages were present. Findings indicate that message spatialization in acoustic space improves auditory performance during times of heavy message competition, even in high-level noise. The proposed technology has numerous applications, such as multichannel communications in tactical operations centers, monitoring of complex security systems, and air traffic control.
Asunto(s)
Dispositivos de Protección de la Cabeza , Audición/fisiología , Percepción del Habla/fisiología , Adulto , Análisis de Varianza , Femenino , Humanos , Masculino , RuidoRESUMEN
The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.
Asunto(s)
Acústica , Localización de Sonidos , Análisis y Desempeño de Tareas , HumanosRESUMEN
The purpose of this study was to measure air-conduction (AC) and bone-conduction (BC) hearing thresholds with pure-tone and filtered sound effect stimuli using standard audiometric equipment. A group of 20 young, normal-hearing listeners participated in the study. Pure-tone stimuli were 250, 500, 1000, 2000, and 4000 Hz. Sound effect stimuli were 12 natural sounds that were spectrally limited to an octave bandwidth centered at either 250, 500, 1000, 2000, or 4000 Hz. The AC and BC detection thresholds were measured using a clinical audiometer (Madsen Orbiter 922) with a B-71 bone oscillator and TDH-50 earphones. Results indicated that detection thresholds for the pure-tone and corresponding octave-band sound effect stimuli were within 3 to 4 dB of each other for both AC and BC testing. The findings support the notion that octave-filtered sound effects are a viable alternative to pure-tone stimuli for use in audiology clinics.
Asunto(s)
Audiometría de Tonos Puros/métodos , Percepción Auditiva/fisiología , Umbral Auditivo/fisiología , Conducción Ósea/fisiología , Adolescente , Adulto , Femenino , Humanos , MasculinoRESUMEN
OBJECTIVE: The study was designed to assess the effects of background noise level on the detection and localization of speech. DESIGN: The phrase "Where is this?" was presented either in quiet or in a diffuse noise field, through loudspeakers arranged in a 360 degrees azimuth array. The noise conditions included 11 signal to noise ratios (SNRs) ranging from -18 dB SNR to +12 dB SNR in 3 dB increments. Seventeen normal-hearing subjects, aged 18 to 29, participated in the study. RESULTS: Results revealed that in all listening conditions the signal was most easily detected when presented through a loudspeaker positioned at 90 degrees or 270 degrees azimuth. Although the actual level for 50% detection varied as a function of loudspeaker location and SNR, 85% and 100% of all presentations of the signal were detected at -9 dB and -6 dB SNR, respectively. Localization accuracy improved as the SNR increased, ranging from 18% accuracy at -18 dB SNR to 89% at +12 dB SNR. Localization accuracy in quiet was 95%. The data are discussed in reference to patterns of responses at each loudspeaker location. CONCLUSIONS: Detection of the target signal deteriorated as background noise level increased and was dependent on the source location of the incoming signal, as expected. Localization accuracy of the target signal was highly dependent on the SNR and spatial location of the signal source. Detection and localization accuracy data were found to be repeatable across test sessions and response patterns were found to be symmetrical on the right and left sides of the horizontal plane.
Asunto(s)
Ruido , Detección de Señal Psicológica/fisiología , Percepción del Habla/fisiología , Adolescente , Adulto , Umbral Auditivo , Ambiente , Femenino , HumanosRESUMEN
The goal of this study was to determine whether selected sound effects that are spectrally limited to an octave band width could be used as alternative stimuli to pure tones when testing children and other special populations. The uniqueness of octave-band sound effects is that they retain the natural character of everyday sounds while providing frequency-specific information about hearing sensitivity. In this study, 20 normal-hearing adults were asked to detect and recognize octave-band filtered musical and environmental sounds presented in quiet and in multitalker noise. Detection and recognition thresholds for the filtered sound effects were compared with respective pure-tone thresholds obtained at 250, 500, 1000, 2000, and 4000 Hz for the same subjects. Results indicate that filtered sound effects are a promising alternative to pure-tone stimuli for use in audiometric tests. Applications and limitations of filtered sound effects as test stimuli for testing children and adults are discussed.