Effects Of Sound Sources Research Articles

Subjective evaluation of sequential spaces

The problem of designing non-acoustic sequential spaces is drawing increasing attention from acoustic researchers and practitioners. For subjective evaluation, the effects of sound source, differences in two directions (either towards or away from a sound source), and factors correlated to acoustic comfort remain unknown. This study employed soundwalk and field measurements with a questionnaire survey of a combination of room acoustics and soundscape indicators in two comparative sequential spaces with similar spatial compositions. The sound source resulted in changes to the perceived loudness, spaciousness, and reverberation. Loudness and reverberation showed a similar tendency. Other indicators, including clarity, listener envelopment, intimacy, warmth, acoustic comfort, annoyance, directivity, and overall impression were not affected. Moving in two directions resulted in different loudness and listener envelopment in the same room, both of which were stronger when moving towards the sound source. Even under the condition of a large spatial difference and a 6 dBA sound level difference, the difference in acoustic comfort in sequential spaces could be only about 0.1. The correlations between acoustic comfort and room acoustics indicators varied with the direction of movements.

Effects of sound source and its direction on subjects' impression of soundscape in workplace

In the ordinary workplace, there exist many kinds of sound. However, workers usually do not intend to listen to them. To keep soundscape in workplace good, it is necessary to know how they feel such sound that they take no notice of. In the present research, one experiment was carried out for the purpose. Twenty subjects participated in the experiment and experienced three kinds of sound source, that is conversation, music, and signal sound, that had sound pressure level of 50 or 60 dBA and presented from four different directions. Results show that sound of 50 dBA has generally better impression than 60 dBA and signal sound of each SPL is recognized as bothering and not calm. On the other hand, 50 dBA of conversation and music that are presented from behind worried subjects little. Besides, 60 dBA of music presented from right and left side of subjects is felt as obstructive as the 50 dBA of signal sound. As a result, it is suggested that soundscape in workplace should be planned with attention to the person's behavior, meaning and volume of sound source, and its spatial layout.

Study on the Measurement of Material Nonlinearity Coefficient Taking into Account Nonlinear Effects of Sound Source

Study on the Measurement of Material Nonlinearity Coefficient Taking into Account Nonlinear Effects of Sound Source

Effects of acoustic source and filtering on time-of-flight measurements

Time-of-flight (TOF) measurements are valuable in the estimation of distances, displacements and velocities of moving objects, phase differences of wave pulses, temperature of the atmosphere, and so on. The effects of sound source on time-of-flight measurements have been investigated in this paper. The sound sources considered are: electric horn, impact noise source, aerodynamic noise from a free jet, and the Hartmann whistle. The focus of the present study is to highlight the advantage of using Hartmann whistle for TOF measurements as this device is simple and attractive, without any moving parts. Time-of-flight of sound waves is calculated by cross-correlating the signals received by two microphones. Further, the effect of signal filtering on TOF measurements is demonstrated. The results indicate that the sound source has considerable effect on TOF measurements, and the accuracy can be significantly enhanced by appropriate signal conditioning. Hartmann whistle proves to be a good candidate as an acoustic source for TOF measurement.

Working group on ‘‘The effects of sound on fish and turtles’’: An update

In order to develop acoustic exposure criteria for fish and marine turtles based on scientific evidence, an ASA Standards Working Group was formed with a membership that includes basic scientists expert on fish and turtle bioacoustics, physical acousticians with special expertise in marine bioacoustics, and several individuals with expertise on effects of anthropogenic sound in the marine environment. This presentation is a summary of the group’s progress to date. One of the Working Group’s goals is to publish several papers, one on what is known about damage risks due to exposure to underwater noise (e.g., from pile driving, seismic exploration, sonar systems), and one assessing the efficacy of various measures to mitigate adverse effects of noise exposure. The working group has tentatively decided that the fish potentially affected should be categorized with respect to their hearing sensitivity (potential for auditory system damage) and whether the species is known to detect sound pressure or acoustic particle motion. Over the next year to 18 months, the Working Group will be evaluating the known effects of sound sources on fish and turtles, identifying areas in which further research is needed, and beginning to develop noise exposure criteria for both turtles and fish.