Browsing by Author "Hongisto, Valtteri"
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- Airborne sound insulation of wall structures : measurement and prediction methods
Doctoral dissertation (article-based)(2000-12-01) Hongisto, ValtteriProtection against noise is one of the six essential requirements of the European Construction Product directive. In buildings, airborne sound insulation is used to define the acoustical quality between rooms. In order to develop wall structures with optimal sound insulation, an understanding of the physical origins of sound transmission is necessary. The purpose of this thesis was, firstly, to study and compare the validity of existing physical models to predict the sound insulation of wall structures, and, secondly, to study the benefits of the sound intensity measurement method for determining the sound insulation. To develop the kind of knowledge that is applicable to the improvement of real wall and door structures was the motive behind this study. Five main results are summarized in the following. 1. It was possible to measure wall structures with a considerably, up to 22 dB, higher sound reduction index with the intensity method than with the pressure method. Thus, the intensity method enables the determination of sound insulation in the presence of strong flanking where the pressure method gives only an underestimate. 2. The sound transmission through doors was modelled by two separate paths: a structural path through the door leaf and a leaking path through the door slits. The structural path was predicted using Sharp's model. The agreement with measurements was reasonably good except at high frequencies where overestimations were obtained. The leaking path was predicted using the model of Gomperts and Kihlman. The agreement with measurements was good for free apertures. 3. Thirteen existing prediction models of double panels were compared. The variations in predicted sound reduction indices were high, 20 ... 40 dB. Further work is needed to rank different models according to their reliability for practical structures. In addition, there is an obvious need to develop a hybrid model where all the important parameters are considered. 4. A new flanking mechanism could be observed in situ for a floating floor covering over a concrete slab. Identical floor structures in adjacent dwellings led to strong flanking transmission at the double panel resonance frequency of the floors. Strong flanking could be avoided by modifying the double structure in one dwelling. 5. In general, the most typical design fault of sound insulating double structures was strong mechanical connections, either in the form of rigid interpanel connections (studs) or in the form of bonded cavity absorbent (sandwich structures). In the case of door structures, efforts are usually wasted on the development of the structure, while the leak transmission may be the main transmission path. The results of this study are useful when the intensity method is used in the presence of strong flanking sound, the sound insulation of wall and door structures are predicted or improved and when prediction models are developed. - Valaistuksen mittaus- ja arviointipalvelutuotteen kehittäminen
Helsinki University of Technology | Master's thesis(2007) Nyman, MarkoTässä työssä perehdytään valaistuksen mittaamiseen ja arviointiin pääasiassa Suomen Valoteknisen Seuran, Illuminating Engineering Society of North America:n ja International Commission on Illumination:in suosituksien perusteella. Tämän pohjalta työssä kehitetään Työterveyslaitokselle palvelutuote sisätyöpaikkojen valaistuksen mittaamiseen ja arviointiin. Työssä käydään läpi valaistuksen laatutekijät ja tyypillisimmät ongelmat, sekä yleiset mittaus- ja arviointimenetelmät ongelmien havaitsemiseksi. Työn yhteydessä kehitettiin myös mittausmenetelmiä kuvantavalle luminanssimittarille. Työssä määritellään myös mahdolliset parannustoimenpiteet sekä esitellään hyvin yksinkertainen kolmiportainen kriteeristö valaistusjärjestelmän korjaustarpeen määrittelyyn. Palvelutuotteen kehittämiseen kerättiin materiaalia suorittamalla mittauksia asiakasyritysten tiloissa. Mittauksissa pyrittiin huomioimaan valaistuksen laatutekijät mahdollisimman kokonaisvaltaisesti. Asiakaskäyntien perusteella luotiin kolmeen osaan jakautuva mittaus- ja arviointipalvelutuote. Palvelutuotetta kehitettäessä havaittiin tiettyjä ongelmia Suomessa käytettävässä sisävalaistussuosituksessa SFS-EN 12464-1. Työalueiden välittömien lähiympäristöjen määrittelylle tarvittaisiin tarkempaa ohjeistusta ja niiden mittaamiseksi olisi luotava yleisesti käytettävät menetelmät. SFS-EN 12464-1 vaatisi tarkennuksia myös esimerkiksi soveltamisen ja luminanssijakauman hallinnan osalta. - Hearing threshold, loudness, and annoyance of infrasonic versus non-infrasonic frequencies
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-09) Rajala, Ville; Hakala, Jarkko; Alakoivu, Reijo; Koskela, Ville; Hongisto, ValtteriResearch related to perception, loudness, and annoyance of infrasound (frequency below 20 Hz) is limited compared to non-infrasound (20–20000 Hz). The purpose was to determine hearing threshold, equal loudness contours, equal annoyance contours, and other sensations apart from hearing. The laboratory experiment involved 19 normal hearing participants. Observed hearing thresholds within 4–8000 Hz agreed with previous findings supporting the adequacy of our methods. Equal-loudness contours for 20, 40, and 60 phon were determined within 4–1000 Hz. They emphasized the non-linear nature of hearing. The dynamic range of hearing is extremely suppressed at infrasonic frequencies: an increment of 5 dB at 4 Hz feels like an increment of 10 dB at 20 Hz and an increment of 20 dB at 1 kHz. Equal-annoyance contours were derived for 20, 40, and 50 phon within 4–1000 Hz. Because individual hearing thresholds varied up to 20 dB, an infrasonic tone still being inaudible for one participant could be loud or annoying for another participant. The finding may explain why some people perceive low frequency sound more annoying than the others. Other sensations apart from hearing (such as pressure in the ear, headache, and vibration sensation) were reported both for infrasound and non-infrasound. Thus, other sensations apart from hearing are not limited to infrasonic frequencies. The study findings emphasize that sound below 20 Hz should be treated similarly as sounds within 20–20000 Hz. Health effect assessment procedures would benefit from standardized hearing threshold below 20 Hz.