Effects of recorded water sounds on intrusive traffic noise perception under three indoor temperatures

Abstract

The effects of indoor water sounds on traffic noise perception were investigated under three room temperatures of 18 °C, 24 °C, and 30 °C through listening experiments with 54 participants. Two types and four levels of water sounds (35, 40, 45, and 50 dBA) were presented with four levels of traffic noise (45, 50, 55, and 60 dBA) in an indoor environmental test laboratory. Water sounds were recorded using a simple indoor fountain comprising a submersible pump and two types of nozzles (foam-jet and mushroom), which generated different water sound spectra. The listeners assessed the thermal and acoustic environments on eleven adjective attributes, representing negative acoustic attributes, positive acoustic attributes, acoustic comfort, thermal comfort, and overall comfort. The results showed that indoor water sounds enhanced pleasantness, calmness, and naturalness without increment of noisiness, loudness, or annoyance in the 30 °C condition, while no perceptual improvement of traffic noise was found in the 18 °C and 24 °C conditions. Room temperature affected both thermal perception and acoustic perception. Water sounds affected not only acoustic perception, but also thermal and overall indoor environmental comfort. A just noticeable water sound level was preferred to mitigate intrusive traffic noise perceptually in a room. The noise perceived in a room should be described by both negative and positive adjectives together, in order to evaluate the effects of indoor environment, such as water sounds and temperature, on noise perception.