Final Thesis

Psychoacoustic Effects of Air Diffuser Noises at the same Loudness Level

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Bachelor Thesis of Akdag, Aykan

This study investigates the impact of air diffuser noise on human well-being, which is relevant due to its widespread use in residential and commercial buildings. The objective is to determine the types of air diffusers that produce the most pleasant noise by conducting a pairwise comparison listening experiment with 32 participants. Seven stimuli were recorded using five different air diffusers at three different air volume flows. The A-weighted sound power level is limited as it only assesses the physical aspects of sound and disregards the subjective perception of noise, which makes it unable to accurately measure the annoyance and acceptance of the systems under investigation. Psychoacoustic characteristics, such as loudness, play a significant role in determining the pleasantness of stimuli. However, in this study, the influence of loudness was eliminated to allow participants to be influenced by other characteristics of the stimuli. To achieve this, loudness of the stimuli were equalized across different volume flows. The results show that preferences for air diffusers varied based on volume flows, and according to participants’ responses, perceived annoyance was influenced by comparisons with familiar noises and imagined environments, alongside personal experiences and sensitivity levels. The findings suggest that there is potential for further investigation into the impact of both sensory and non-sensory factors on perceived annoyance. The study’s findings highlight the importance of considering both the technical specifications and acoustic properties of air diffusers when selecting them for indoor installations. This has practical implications for air diffuser design, operation, and the development of noise regulations and guidelines for ventilation system design and installation.