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17.05/17.07 Sound Quality & Consumer Product Noise

Digitalizing sound in personal spaces
Time: 8:40 am

Author: Ramana Kappagantu

Abstract ID: 1884

Design specifications for appliances are usually in the context of standard acoustic rooms like anechoic (full or hemi) and sometimes reverberant.  However in the world of infotainment industry the devices are operated in your personal space - a generic environment like that of a living room and they continuously interact with other devices in real time.  One has to take into account the scattering and absorption of sound from different surfaces and how they constructively and destructively interfere in generating a signature sound for the room and the devices. This environmental impact increases the design space significantly and makes it impractical to consider physical prototyping and testing.  Simulating the acoustic behavior of the devices in a room environment has been attempted in the past and were successful only for lower frequency ranges or for smaller rooms. High end Multipole BEM and FEM Adaptive Order technologies have emerged in the recent past and together with parallel cloud computing make the modeling of generic room environment more feasible, up to a few kHz given adept hardware setup. A different, more asymptotic method like Ray Tracing provides a real breakthrough here and enables taking on the full audible frequency range and large rooms, in at least one order of magnitude faster solving times compared to the more conventional FEM and BEM method, which further supports optimization possibilities for different configurations in reasonable time.

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Parameter study of Variation noise in outdoor of air conditioner
Time: 7:40 am

Author: KIM Minkyu

Abstract ID: 2238

In the outdoor unit of a room air conditioner, the main factors that made it possible to vary the ability of cooling and heating are the development of BLDC motors, advances in inverter technology, and the development of refrigerant volume control technology. The main reason for this change in cooling and heating capacity is that it is possible to change the RPS of compressors. As the range of the compressor's RPS expands, so does the range of response to load variations. This is mainly based on the capacity of the high-pressure refrigerant produced by the compressor. When the compressor rotates at high speed or low speed, the difference in noise occurs depending on the difference in rotational speed. Of course, fans and motors also contribute to noise fluctuations, but the overall governing factor is the greater contribution of refrigerant from compressors and compressors. The refrigerant flows into the cycle configured in the outdoor unit and varies in speed and flow rate depending on the amount of refrigerant. This results in vibration and noise appearing in the form of radiations, resonances, solid sounds, resonances, and so on. There are several factors that can cause vibration or noise changes depending on the flow velocity and flow rate. In this paper, we selected reactance of compressor motors, mufflers directly connected to compressor discharge ports and accumulator at compressor inlet where fluid vibrations occur the most. First of all, reactance of motor responds quickly to load fluctuations and has a large instantaneous torque to instantaneous load fluctuations. The muffler, which is directly connected to the compressor discharge port, is the first Cavity where high-pressure gas meets, and can evaluate the concentration of kinetic energy that generates noise and improve the collection center to reduce fluctuating noise. The Accumulator is the part with the lowest temperature of refrigerant gas entering the compressor, and the rapid change in the flow path causes the most fluid to generate vibration and radiation of the structure. For this reason, we select three elements first. In this paper, we specifically describe the background of selecting three elements of an air conditioning outdoor unit for the variability of noise over RPS changes. We demonstrate that these factors can review the feasibility of the experiment, explain the results of the analysis, and possibility of reduce the variation noise.

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Understanding the relationship between onomatopoeic expressions and sound quality for rotary switch operating sounds
Time: 7:20 am

Author: Toru Miyairi

Abstract ID: 1745

In our daily lives, we often use onomatopoeia to convey images of products. However, the correspondence between onomatopoeia and physical quantities is not clear. To apply onomatopoeia to product design, we focused on the relationship between the sound symbolism of onomatopoeia and product sound quality. The target of the evaluation was the operation sound of the rotary switch. A subjective evaluation experiment was conducted in which participants were asked to free answer to the impressions associated with the operation sounds using onomatopoeic expressions. The obtained onomatopoeia was then analyzed by quantitative text analysis using mora as the unit of analysis. The results showed the voiced consonants appeared more frequently in the louder operation sounds. In addition, the vowel /o/ appeared more frequently in sounds with low sharpness, and the vowel /i/ appeared more frequently in sounds with high sharpness. Since these trends are similar to other studies on sound symbolism, this study shows the possibility of using onomatopoeia in product design by utilizing sound symbolism.

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MOSQITO: an open-source and free toolbox for sound quality metrics in the industry and education
Time: 8:00 am

Author: Roberto San Millán-Castillo

Abstract ID: 1767

Sound quality metrics provide an objective assessment of the psychoacoustics of sounds. A wide range of metrics has been already standardised while others remain as active research topics. Calculation algorithms are available in commercial equipment or Matlab scripts. However, they may not present available data on general documentation and validation procedures. Moreover, the use of these tools might be unaffordable for some students and independent researchers. In recent years, the scientific and technical community has been developing uncountable open-source software projects in several knowledge fields. The permission to use, study, modify, improve and distribute open-source software make it extremely valuable. It encourages collaboration and sharing, and thus transparency and continuous improvement of the coding. Modular Sound Quality Integrated Toolbox (MOSQITO) project relies on one of the most popular high-level and free programming languages: Python. The main objective of MOSQITO is to provide a unified and modular framework of key sound quality and psychoacoustics metrics, free and open-source, which supports reproducible testing. Moreover, open-source projects can be efficient learning tools at University degrees. This paper presents the current structure of the toolbox from a technical point of view. Besides, it discusses open-source development contributions to graduates training.

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Sound quality evaluation for luxury refrigerator door closing sound
Time: 8:20 am

Author: Kanta Imamori

Abstract ID: 1968

In this study, we carried out subjective evaluation tests employing 19 refrigerator door closing sounds to quantify the luxury feeling. By applying factor analysis to the subjective evaluation results, the sound quality of the refrigerator door closing sound was found to be expressed by the following two factors: overall loudness and the pitch of the sound. Subsequently, luxury feeling evaluation model was obtained through multiple regression analysis. As the result, the luxury feeling of the door closing sound was evaluated to be high when the sound was softer and had lower pitch. Then, we prepared several luxury door closing sounds according to the obtained evaluation model through a filter processing and conducted subjective evaluation tests again to verify the evaluation model. The result shows that the amplitude increased sound at low frequency band under 100 Hz, which was calculated to be high luxury by the evaluation model, was actually evaluated as the best among the presented sounds through the subjective test. And the luxury sound quality evaluation method was confirmed to be useful to quantify and estimate the sound quality of the refrigerator door closing sound.

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