Jin You

Evaluating water sounds to improve the soundscape of urban areas affected by traffic noise

The acoustic characteristics of various kinds of water sounds were investigated to evaluate their suitability for improving the soundscape with road traffic in urban spaces. Audio recordings were made in urban spaces with water features such as fountains, streams, water sculptures, or waterfalls. The temporal and spectral aspects of the sounds were clarified, and subjective evaluations were performed to find the proper level difference between water sounds and road traffic noise for making urban soundscape more subjectively pleasant. The results indicated that the perceptual difference of the water sound level was around 3 dB with noises from road traffic in the background. The water sound, which had 3 dB less sound pressure level, was evaluated as preferable when the levels of road traffic noise were 55 or 75 dBA. It was also found that water sounds with relatively greater energy in low-frequency ranges were effective for masking noise caused by road traffic. The results of the present study will be valuable to urban designers and planners by providing guidelines for improving design solutions for water features in urban soundscape

Sound quality characteristics of refrigerator noise in real living environments with relation to psychoacoustical and autocorrelation function parameters

Psychoacoustical and autocorrelation function (ACF) parameters were employed to describe the temporal fluctuations of refrigerator noise during starting, transition into/from the stationary phase and termination of operation. The temporal fluctuations of refrigerator noise include a click at start-up, followed by a rapid increase in volume, a change of pitch, and termination of the operation. Subjective evaluations of the noise of 24 different refrigerators were conducted in a real living environment. The relationship between objective measures and perceived noisiness was examined by multiple regression analysis. Sound quality indices were developed based on psychoacoustical and ACF parameters. The psychoacoustical parameters found to be important for evaluating noisiness in the stationary phase were loudness and roughness. The relationship between noisiness and ACF parameters shows that sound energy and its fluctuations are important for evaluating noisiness. Also, refrigerator sounds that had a fluctuat...

Sound Quality Characteristics of Refrigerator Noise in Real Living Environments

Psychoacoustical and autocorrelation function (ACF) parameters were employed to describe the temporal fluctuations of refrigerator noise during starting, transition into/from the stationary phase and termination of operation. The temporal fluctuations of refrigerator noise include a click at start-up, followed by a rapid increase in volume, a change of pitch, and termination of the operation. Subjective evaluations of the noise of 24 different refrigerators were conducted in a real living environment. The relationship between objective measures and perceived noisiness was examined by multiple regression analysis. Sound quality indices were developed based on psychoacoustical and ACF parameters. The psychoacoustical parameters found to be important for evaluating noisiness in the stationary phase were loudness and roughness. The relationship between noisiness and ACF parameters shows that sound energy and its fluctuations are important for evaluating noisiness. Also, refrigerator sounds that had a fluctuation of pitch were rated as more annoying. The tolerance level for the starting phase of refrigerator noise was found to be 33 dBA, which is the level where 65% of the participants in the subjective tests were satisfied.

Urban space design based on the perceptual assessment of soundscape.

In the present study, urban soundscape has been investigated by social survey and soundwalking. An intensive social survey using 11‐point numerical scale was carried out with narrative interviews; the dominant contexts affecting the perception of urban soundscape were derived from the survey: visual image, acoustic comfort, and natural brightness. Thus, the effects of contexts on the perception of soundscape were also confirmed by soundwalking. In addition, the effects of water sounds on the enhancement of urban soundscape were examined; auditory experiments were performed to enhance the perception of urban spaces with various kinds of water sounds. Water sound, which had 3 dB less than urban noise, was found as a preferable masker. Visual images, as well as acoustical characteristics of water sounds, had an effect on the perception of urban soundscape.

Evaluation of Sound Quality of Air-conditioning Noise

Noise from air-conditioner system installed in the ceiling of a classroom was evaluated to investigate the sound quality of air-conditioning noise. Harmonics of air-conditioning noise were removed and the sound pressure levels of the frequency bands from were changed to control sound quality. Evaluation for refreshing sensation was conducted using a paired comparison method and the results showed that noise without harmonics were preferred to noise with harmonics. The noises which have larger level increases to the unchanged noise at were evaluated better in both of the noises with and without harmonics. Results of multiple regression analysis on psychoacoustic parameters and subjective preferences showed sharpness as a major affecting factor in describing the refreshing aspect of air-conditioning sound.

Subjective and objective evaluation of air‐conditioning noise

Noise from an air‐conditioning system installed in the ceiling of classrooms was evaluated to investigate the subjective responses to air‐conditioning noise. Harmonics of air‐conditioning noise was removed and the sound‐pressure levels of the frequency bands from 250 to 630 Hz were varied to control sound quality. Evaluation for air‐conditioning noise sensation was conducted using a paired comparison method and the results showed that noise without harmonics was preferred to noise with harmonics. The noises which have larger level increases to the noise at 250 to 630 Hz were evaluated better in both of the noises with and without harmonics. Results of multiple regression analysis on psychoacoustic parameters and subjective preferences showed sharpness as a major factor in describing the sound quality of air‐conditioning noise. A semantic differential test was also conducted to evaluate the sound‐quality characteristics of air‐conditioning noise.

Radiation properties and sound quality characteristics of refrigerator noise

The characteristics of refrigerator noise in an anechoic chamber and in an actual environment were investigated. In order to predict the noise propagation in real apartment house, room acoustic simulations and measurements using different types of refrigerators were conducted. The sound‐pressure level of the refrigerator noise in the real living room was much higher than in the anechoic chamber. In addition, an allowable sound‐pressure level for refrigerator noise was determined by auditory experiments. For the stimuli of auditory experiments, the dry source of refrigerator noise was presented using a loud speaker at the position of the refrigerator. When the result of the subjective evaluation was at the level 2 (the noise rarely aware but comfortable), in which sound pressure level was about 25 dB(A), 95% of people were satisfied with the refrigerator noise. A semantic differential test using various adjectives was also conducted to evaluate the sound quality of refrigerator noise.