The suitability of internal combustion engine sounds as artificial warning sounds for electric and hybrid vehicles

The paper discusses the issue of adding artificial warning sounds to hybrid and fully electric vehicles, in order to increase traffic safety by making these vehicles audible at low speeds. The goal of this modification is to enable the pedestrians to perceive possible danger coming from such a vehicle in time to respond accordingly. Following the results of previous research which state that the sounds of internal combustion engines are valid candidates for artificial warning sounds to be added to hybrid or fully electric vehicles, a preliminary examination of the suitability and acceptability of different engine sounds in various modes of operation has been conducted. The chosen modes of operation are running in idle, at 2000 rpm and 3000 rpm with the vehicle stopped. Both gasoline and diesel engines were investigated. To expand the range of engine sounds, the type of vehicles was not limited to personal cars. The results show significant differences in suitability of engine sounds for the stated purpose, with vehicle type being the main differentiating factor

Performance of Traffic Noise Barriers with Varying Cross-Section

The efficiency of noise barriers largely depends on their geometry. In this paper, the performance of noise barriers was simulated using the numerical Boundary Element Method (BEM). Traffic noise was particularly considered with its standardized noise spectrum adapted to human hearing. The cross-section of the barriers was varied with the goal of finding the optimum shape in comparison to classical rectangular barriers. The barrier performance was calculated at different receiver points for a fixed barrier height and source position. The magnitude of the insertion loss parameter was used to evaluate the performance change, both in one-third octave bands and as the broadband mean insertion loss value. The proposed barriers of varying cross-section were also compared with a typical T-shape barrier of the same height

Spectral characteristics of klapa singing performed by professional folk singers

Cilj je istraživanja bio ispitati spektralne karakteristike klapskoga pjevanja, te utvrditi oslanja li se ovaj način pjevanja na pjevački formant. Analiziralo se glasove dvanaestorice profesionalnih folklornih pjevača. Svaki je otpjevao dalmatinsku pjesmu Zaspalo je siroče u Gduru. Pojedinačne se glasove snimalo digitalno, a analiza dugotrajnoga prosječnog spektra učinjena je u programu PRAAT. U obliku spektra pjevača nisu ustanovljena obilježja koja bi upućivala na pjevački formant. U području frekvencija 2.2-3.7 kHz uočena su dva vrha (treći i četvrti formant), te oblik spektra koji je sličan obliku spektra govora. U spektrima je nekih pjevača nešto naglašeniji četvrti formant, te ima obilježja govorničkoga formanta. Zbog ispitivanja sličnosti klapskoga pjevanja i govora, u istraživanje je naknadno uveden uzorak govornika (N=8). Računalo se i uspoređivalo nagib spektralne ovojnice prema visokim frekvencijama, prosječnu jakost pojaseva širine tisuću herca (1-2 kHz, 2-3 kHz, 3-4 kHz i 4-5 kHz), te parametre alfa i VF (jakost visokih formanata). Rezultati ovih obrada pokazali su da su spektralne karakteristike klapskoga pjevanja i govora slične. No razlike postoje u jakosti područja frekvencija 2-4 kHz (parametar VF). Spektar je klapskoga pjevanja ovdje pojačan, no to pojačanje nema sličnosti s pjevačkim formantom. Zaključuje se da je produkcija klapskoga pjevanja usporediva s produkcijom (kultiviranoga) govora.The purpose of this research was to examine the spectral characteristics of klapa singing and to show if this type of singing relies on a singer’s formant. The voices of twelve professional male folk singers were digitally recorded and analysed for long-term average spectrum (LTAS) in the PRAAT program. Each singer performed the Dalmatian song Zaspalo je siroče in G-major. The LTAS contour showed no evidence of a singer’s formant. Instead, the averaged LTAS curve with two distinctive peaks between 2.2 kHz and 3.7 kHz (these correspond to the third and fourth formants) turned out to have features quite similar to a speech spectrum. A more pronounced fourth formant in the case of some singers turned out to have the features of a speaker’s formant. In order to examine the similarities between klapa singing and speech, a sample of speaker subjects (N=8) was subsequently included in the study. The spectral slope and average intensity in the bands 1-2 kHz, 2-3 kHz, 3-4 kHz and 4-5 kHz as well as alfa and VF (strength of the high formants) parameters were computed and compared. The results showed that spectral characteristics of klapa singing and speaking were comparable. However, the differences were noticeable in intensity levels in 2-4 kHz frequency range (VF parameter). In this case the klapa singing spectrum was intensified but there were no sings of the singer’s formant. The conclusion is that the production of klapa singing is comparable to that of (trained) speech

ANALIZA DU GOTRAJNOGA PROSJEČNOG SPEKTRA OJKANJA

Ojkanje je način pjevanja karakterističan za glazbeno-folklornu tradiciju gorske Hrvatske, tj. dalmatinsko zaleđe i šire dinarsko područje. Opisano je etnomuzikološki, ali ne i akustički. Ciljevi ovog eksplorativnog istraživanja bili su analiza dugotrajnoga prosječnog spektra (LTAS) ojkanja te utvrđivanje pjevačkog formanta. U istraživanju je dobrovoljno sudjelovalo dvanaest profesionalnih izvođača hrvatskih narodnih pjesama i plesova. Akustička analiza glasa obavljena je primjenom računalnog programa PRAAT. Provedena je i samopercepcijska procjena ojkanja. Analiza ugotrajnih prosječnih spektara glasova pjevača pokazala je izrazitu jakost glasa kao glavnu karakteristiku, a to se istaklo i kao najznačajnije percepcijsko obilježje. Pjevački formant nije utvrđen, no u višem dijelu spektra na oko 3,2-3,5 kHz ustanovljeno je pojačanje koje odgovara govorničkom formantu. Kako je riječ o spektrima pjevanog, a ne govornoga glasa, ovaj visoki formant zaslužuje primjereniji naziv. Budući da je on ponajprije rezultat izrazito glasnog pjevanja koje graniči s vikanjem, predložen je naziv vikački formant. Osim izrazite glasnoće, kao ostala važna percepcijska obilježja ojkanja izdvojili su se napetost grla, muževnost i otvorenost glasa. Rezultati ovog i sličnih istraživanja na problemskom području akustike folklornog pjevanja doprinos su znanosti o glasu te etnomuzikologiji, a mogu imati i praktičnu vrijednost unutar pjevačke pedagogije koja više nije ograničena samo na operno pjevanje

Projektiranje akustičnih filtera metodom raspodjeljenih parametara

Prilikom projektiranja akustičkih filtara, velika je poteškoća proračun odgovarajuće frekvencijske karakteristike. Metoda raspodijeljenih parametara uz elektro-akustičke analogije omogućuje dobivanje realnih frekvencijskih karakteristika. Primjenom računala moguće je proračunati dimenzije i oblik akustičkog filtra odgovarajuće frekvencijske karakteristike i odgovarajuće razine gušenja

Noise Levels in a Pedodontic Dental Practice

Svrha rada bila je odrediti razinu buke u pedodontskoj stomatološkoj ordinaciji koja prije toga nije bila akustički obrađena te anketirati stomatologe kako bi se procijenila izvrgnutost neželjenim zvukovima stomatoloških uređaja tijekom redovitoga dnevnog radnog vremena. Mjerenje buke obavljeno je u Zavodu za pedodonciju Stomatološkog fakulteta Sveučilišta u Zagrebu u ordinaciji sa šest radnih mjesta, a koristili su se najčešće potrebni stomatološki nastavci (turbina s vodom, mikromotor s vodom i bez vode, puster i SONICfl ex). Odabrana su dva načina ispitivanja - tradicionalna, normirana metoda jednokanalnoga zvukomjera s modulom za spektralnu analizu te nova dvokanalna metoda pomoću umjetne glave. Ekvivalentna razina osnovne buke izmjerena s korekcijskim fi ltrom A (LAeq) iznosila je LAeq = 54,4 dB (decibela). Razina buke u lijevom uhu umjetne glave bila je 53 dB, a u desnom 55 dB. Buka koja se stvara tijekom rada turbine s vodom iznosila je LAeq = 81 dB, mikromotora s vodom LAeq = 75 dB, mikromotora bez vode LAeq = 72,5 dB, pustera LAeq = 81,5 dB i SONICfl ex LAeq = 76 dB. Ekvivalentna razina buke kojoj je izložen stomatolog bila je LAeq = 72,1 dB, što uz korekciju zbog tonalne buke iznosi LAeq = 77,1 dB. Na temelju dobivenih rezultata može se zaključiti da je buka – iako ekvivalentna razina buke ne premašuje LAeq = 90 dB, što bi bio razlog za urgentno djelovanje - ipak veća od LAeq = 70 dB, a to je gornja granica dopuštena prema odredbama Pravilnika o zaštiti na radu. Kako buci u ordinaciji nije izvrgnut samo terapeutski tim nego i pedodontski pacijent, trebalo bi akustički obraditi prostoriju u kojoj se obavlja djelatnost, kako bi se smanjile neželjene posljedice poput straha, stresa i uznemirenosti pacijenata.The aim of this paper was to measure the level of noise in the pedodontic practice, which hasn’t been acoustically treated, and to interview the dentists in order to determine their exposure to undesired noise of dental equipment during daily work. The measurement of noise was conducted at the Department of Pedodontics, School of Dental Medicine, Zagreb, using the most frequently used handpieces (turbine, micromotor with and without water, air syringe and SONICfl ex). A standardised method of noise measurement was applied, by means of a single-channel sound level meter; and a new dual-channel method, by means of an artifi cial head. The equivalent level of background noise with a correction fi lter A (LAeq) was LAeq = 54.4 dB (decibel). The noise level in the left ear of the artifi cial head was 53 dB and in the right ear 55 dB. The noise made by a turbine was LAeq = 81 dB, by the micromotor with water LAeq = 75 dB, by the micromotor without water LAeq = 72.5 dB, by the air syringe LAeq = 81.5 dB and by SONICfl ex LAeq = 76 dB. The level of noise the dentist was exposed to was LAeq = 72.1 dB. It can be concluded that the equivalent level was above LAeq = 70 dB, which is the limit prescribed by the Safety at Work Regulations. Since it is not only the therapist that is exposed to noise, but also the pedodontic patient, it would be advisable to treat the room acoustically in order to reduce undesired consequences of the noise, such as the patient’s fear, stress and anxiety

Noise Levels in a Pedodontic Dental Practice

Svrha rada bila je odrediti razinu buke u pedodontskoj stomatološkoj ordinaciji koja prije toga nije bila akustički obrađena te anketirati stomatologe kako bi se procijenila izvrgnutost neželjenim zvukovima stomatoloških uređaja tijekom redovitoga dnevnog radnog vremena. Mjerenje buke obavljeno je u Zavodu za pedodonciju Stomatološkog fakulteta Sveučilišta u Zagrebu u ordinaciji sa šest radnih mjesta, a koristili su se najčešće potrebni stomatološki nastavci (turbina s vodom, mikromotor s vodom i bez vode, puster i SONICfl ex). Odabrana su dva načina ispitivanja - tradicionalna, normirana metoda jednokanalnoga zvukomjera s modulom za spektralnu analizu te nova dvokanalna metoda pomoću umjetne glave. Ekvivalentna razina osnovne buke izmjerena s korekcijskim fi ltrom A (LAeq) iznosila je LAeq = 54,4 dB (decibela). Razina buke u lijevom uhu umjetne glave bila je 53 dB, a u desnom 55 dB. Buka koja se stvara tijekom rada turbine s vodom iznosila je LAeq = 81 dB, mikromotora s vodom LAeq = 75 dB, mikromotora bez vode LAeq = 72,5 dB, pustera LAeq = 81,5 dB i SONICfl ex LAeq = 76 dB. Ekvivalentna razina buke kojoj je izložen stomatolog bila je LAeq = 72,1 dB, što uz korekciju zbog tonalne buke iznosi LAeq = 77,1 dB. Na temelju dobivenih rezultata može se zaključiti da je buka – iako ekvivalentna razina buke ne premašuje LAeq = 90 dB, što bi bio razlog za urgentno djelovanje - ipak veća od LAeq = 70 dB, a to je gornja granica dopuštena prema odredbama Pravilnika o zaštiti na radu. Kako buci u ordinaciji nije izvrgnut samo terapeutski tim nego i pedodontski pacijent, trebalo bi akustički obraditi prostoriju u kojoj se obavlja djelatnost, kako bi se smanjile neželjene posljedice poput straha, stresa i uznemirenosti pacijenata.The aim of this paper was to measure the level of noise in the pedodontic practice, which hasn’t been acoustically treated, and to interview the dentists in order to determine their exposure to undesired noise of dental equipment during daily work. The measurement of noise was conducted at the Department of Pedodontics, School of Dental Medicine, Zagreb, using the most frequently used handpieces (turbine, micromotor with and without water, air syringe and SONICfl ex). A standardised method of noise measurement was applied, by means of a single-channel sound level meter; and a new dual-channel method, by means of an artifi cial head. The equivalent level of background noise with a correction fi lter A (LAeq) was LAeq = 54.4 dB (decibel). The noise level in the left ear of the artifi cial head was 53 dB and in the right ear 55 dB. The noise made by a turbine was LAeq = 81 dB, by the micromotor with water LAeq = 75 dB, by the micromotor without water LAeq = 72.5 dB, by the air syringe LAeq = 81.5 dB and by SONICfl ex LAeq = 76 dB. The level of noise the dentist was exposed to was LAeq = 72.1 dB. It can be concluded that the equivalent level was above LAeq = 70 dB, which is the limit prescribed by the Safety at Work Regulations. Since it is not only the therapist that is exposed to noise, but also the pedodontic patient, it would be advisable to treat the room acoustically in order to reduce undesired consequences of the noise, such as the patient’s fear, stress and anxiety