Swedish National Road and Transport Research Institute (VTI), Linkoping, -, SE-58195, Sweden
Popular version of 1pNSb9 – Acoustic labelling of tires, road vehicles and road pavements: A vision for substantially improved procedures
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0022814
Not many vehicle owners know that they can contribute to reducing traffic noise by making an informed choice of their tires, while not sacrificing safety or economy. At least you can do so in Europe, where there is a regulation requiring tires be labelled with noise level (among others). But it has substantial flaws for which we propose solutions by applying state-of-the-art and innovative solutions.
It is here where consumer labels come in. In most parts of the world, we have consumer labels including noise levels on household appliances, lawn mowers, printers, etc. But when it comes to vehicles, tires, and road pavements, a noise label on the product is rare. So far, it is mandatory only on tires sold in the European Union, and it took a lot of efforts of noise researchers to get it accepted along with the more “popular” labels for energy (rolling resistance), and wet grip (skid resistance). Figure 1 shows and explains the European label.
Figure 1: The present European tire label, which must be attached to all tires sold in the European Union, here supplemented by explanations.
Why so much focus on tires? Figure 2 illustrates how much of the noise energy that comes from European car tires compared to the “propulsion noise”; i.e. noise from engine, exhaust, transmission, and fans. For speeds above 50 km/h (31 mph) over 80 % of the noise comes from tires. For trucks and busses, the picture is similar although above 50 km/h it may be 50-80 % from the tires. For electric powered vehicles, of course, the tires are almost entirely dominating as a noise source at all speeds. Thus, already now but even more in the future, consumer choices favouring lower noise tires will have an impact on traffic noise exposure. To achieve this progress, tire labels including noise are needed, and they must be fair and discriminate between the quiet and the noisy.
Figure 2: Distribution of tire/road vs propulsion noise. Calculated for typical traffic with 8 % heavy vehicles in Switzerland [Heutschi et al., 2018].
The EU label is a good start, but there are some problems. When we have purchased tires and made noise measurements on them (in A-weighted dB), there is almost no correlation between the noise labels and our measured dB levels. To identify the cause of the problem and suggest improvements, the European Road Administrations (CEDR) funded a project named STEER (Strengthening the Effect of quieter tyres on European Roads), also supplemented by a supporting project by the Swedish Road Administration. STEER found that there were two severe problems in the noise measuring procedure: (1) the test track pavement defined in an ISO standard showed rather large variations from test site to test site, and (2) in many cases only the noisiest tires were measured, and all other tires of the same type (“family”) were labelled with the same value although they could be up to 6 dB quieter. Such “families” may include over 100 different dimensions, as well as load and speed ratings. Consequently, the full potential of the labelling system is far from being used.
The author’s presentation at Acoustics 2023 will deal with the noise labelling problem and suggest in more detail how the measurement procedures may be made much more reproducible and representative. This includes using special reference tires for calibrating test track surfaces, production of such test track surfaces by additive manufacturing (3D printing) from digitally described originals, and calculating the noise levels by digital simulations, modelling, and using AI. Most if not all the noise measurements can go indoors, see an existing facility in Figure 3, to be conducted in laboratories that have large steel drums. Also in such a case a drum surface made by 3D printing is needed.
Figure 3: Laboratory drum facility for measurement of both rolling resistance and noise emission of tires (both for cars and trucks). Note the microphones. The tire is loaded and rolled against one of the three surfaces on the drum. Photo from the Gdansk University of Technology, courtesy of Dr P Mioduszewski.
Kent L. Gee – firstname.lastname@example.org
Twitter (x): @KentLGee
Brigham Young University, Provo, UT, 84602, United States
Logan T. Mathews, Bradley McLaughlin, Mark C. Anderson (@AerospaceMark), Grant W. Hart
Brigham Young University, Utah, USA
Monash University, Victoria, Australia
Popular version of 5PNSa1 – Rocket noise: What does it mean for Australian spaceports?
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023749
The global space industry is rapidly expanding. Rockets are being launched from a greater number of spaceports and a recent exponential increase in annual global orbital launches (Figure 1) has surpassed numbers seen during the 1960s’ Space Race. While about 75% of rockets are currently launched from the United States and the People’s Republic of China, an increasing number of countries are tapping into a global space launch services market projected to reach USD 33.4 billion in 2028. The Australian Space Agency was created in 2018 to support the growth of Australia’s space industry and the use of space across the broader economy. Australia is well-situated for launching payloads to a variety of orbits and multiple spaceports are being constructed or planned.
Figure 1. Global orbital launches by year.
The power generated by rockets during liftoff and ascent generates lots of noise, which can cause possibly damaging vibration of the payload, rocket, and launchpad structures. Farther away, the noise may have short and long-term impacts on communities and the environment, although these impacts are at present poorly understood.
Rocket noise is generated by the high-speed turbulent exhaust plume mixing with the outside air. Although less than 1% of the plume’s mechanical power is turned into sound during liftoff, even a small orbital rocket creates several times more sound power than a military jet aircraft at afterburner. The most powerful orbital rocket, NASA’s Space Launch System (SLS), generates sound power equal to nearly 900 T-7A aircraft.
Near-term, orbital rockets that will launch from Australian spaceports are relatively small. From U.S.-based Phantom Space’s Daytona rocket to Gilmour Space Technologies’ Australian-built Eris rocket, these vehicles will have a much smaller noise footprint than SLS or SpaceX’s oft-launched rocket, the Falcon 9 (see Fig. 2.) However, peak noise levels within several meters of these rockets will still exceed 180 dB and maximum sound levels tens of kilometers away will be above typical background noise, particularly at low frequencies. For example, Figure 3 is a maximum sound level map from a small rocket launched to the east over the Great Barrier Reef. Maximum launch levels along portions of the reef are predicted to be 70-75 dB, not including the ascent sonic boom, which can be significantly louder.
Figure 2. Near-term orbital launch vehicles to be launched from Australia are significantly smaller than the well-known Falcon 9.
Figure 3. RUMBLE-predicted maximum sound level footprint over the Great Barrier Reef for a small orbital rocket launch from the Bowen Orbital Spaceport.
Will launches from Australian soil create damaging vibrations or harmful environmental noise impacts? That is a complex question that depends on vehicle size and design, launch cadence, distance to structures, habitats, and communities, weather patterns, and other factors. Continued study of the multiple facets of generation, propagation, and reception of rocket noise will help find answers and improve our access to space, from Australia and worldwide.
Our acoustic environment is a critical part of our everyday experience; it is often unconsciously processed with all other stimuli to form an impression of a place and time, but its impact is not always fully understood. Soundscape is a method of assessing the acoustic environment where perception is prioritized. The soundscape method and the soundwalk tool integrate measurements of the human perception of sound with other observations that characterize the environment, such as the sound levels, the type of location and the various sound sources. The combination of these perceptual measurements with other observations helps us to understand how the acoustic environment impacts the people there and can provide directions for possible changes that can improve their quality of life.
The soundscape method suggests assessing all sounds which occur in an environment using collected data related to human perception, the physical acoustic setting, and context. Context includes visual cues, geographic, social, psychological and cultural aspects, including one’s mental image or memory of a place. Soundscape transcends the common studies of noise and sound levels, and is a powerful tool for effecting positive results with regard to the quality of life for stakeholders in the acoustic environment; standardized methodology has been developed that can be adapted to various applications, using sound as a resource. Soundwalks are an important part of the soundscape method and are a useful way to engage stakeholders who participate by consciously observing and evaluating the soundscape.
A soundwalk is an element of the soundscape method that typically will include a walking tour of observation locations over a predetermined route to solicit perceptual feedback from the participants regarding the acoustic environment (see Figures 1 and 2). The participants of the soundwalk typically include stakeholders or “local experts”: members of the community that experience the soundscape daily, users/patrons of a space, residents, business people, and local officials. Soundwalks can be performed from urban areas to wilderness settings, indoors and outdoors; the information collected can have many applications including ordinances and planning, preservation or improvement of the acoustic environment, and building public/self-awareness of the acoustic environment.
The perceptual information collected during a soundwalk includes the sounds heard by the participants and often directed questions with scaled answers; this along with objective sound level measurements and audio recordings can be used to assess an acoustic space(s) in an effort to effect the purpose of the soundwalk. (see Figures 3 and 4) In some cases, the participants are interviewed to get a deeper understanding of their responses or the data can be taken to a lab for further study.
The soundwalk and post processing of collected information is flexible relative to soundscape standard methods to target an acoustic space and purpose of the investigation. This makes it an adaptable and powerful tool for assessing an acoustic environment and improving the quality of life for the those that live in or use that environment, using their own perceptions and feedback.
How do we manage noise emissions from the largest rail project in Australia? The answer to that question is not trivial, especially if the project spans across the three eastern coast states of Australia. Currently Australia’s longest rail project, Inland Rail, is a proposed 1600 km rail line that connects Melbourne to Brisbane freight in 24 hours via the States of Victoria, New South Wales (NSW) and Queensland, with a combination of new rail infrastructure and upgrade of existing infrastructure.
image courtesy of inlandrail.com.au
Rail noise across each State is regulated and managed differently with their respective guidelines and policy documents. Victoria and NSW have day and night decibel thresholds, whilst Queensland has a 24-hour exposure threshold. Similarly, for sections where existing rail are being upgraded, all three States have slightly different thresholds which include an absolute threshold in Queensland or a combination of an absolute threshold and a relative increase in noise in Victoria and NSW. Furthermore, considerations of factors which affect rail noise such as rail speeds, track joints, level crossing bells and train horns are considered differently across the three States. In this regard, the modelling of future rail noise levels needs to carefully account for these differences to assess the predicted impacts in each jurisdiction against the respective thresholds.
One important parameter for assessing rail noise impacts is a pass-by maximum noise level (Lmax). This parameter is critical for a freight-dominated project like Inland Rail as it quantifies the impact of locomotives as they go past the residences. Typically, this is assessed as a 95th percentile Lmax, which means that any unusually rare and loud events are excluded (as they would fall within the top 5%). However, in Queensland, the criterion is a Single Event Maximum (SEM) defined as the arithmetic average of the 15 loudest pass-by maximum levels within a given 24-hour period. This parameter is challenging to predict, especially for new rail infrastructure where it is not possible to measure the SEM on field. To overcome this challenge, a prediction method based on a ‘Mote-Carlo’ statistical model was adopted. In this model, rail pass-by noise levels are randomly picked from databases of numerous pass-by noise levels to simulate the noise levels on a given day, and these random values are averaged to obtain the SEM. This random selection of train pass-bys is repeated several thousand times to obtain a trend and derive the most likely SEM that can be expected on field. This mathematical prediction technique was tested on existing rail lines and found to correlate well with field measurements.
There exists a need to support a consistent project-wide rail noise criteria that is effective in addressing all the nuanced differences in the criteria, whilst being simple and effective to implement and understand for all stakeholders. We recommend technical assessments and engagement with state authorities early in the project development phase to investigate noise emissions, controls and development of appropriate criteria. Once approved, the project criteria can be used across all sections of the project to ensure residents adjacent to the project get a consistent outcome.
Picture a typical evening in the heart of a bustling city: pubs and bars come alive, echoing with laughter, music, and the clink of glasses. These hubs of social life create a vibrant tapestry of sounds. But what happens when this symphony overshadows the tranquility of those living just around the corner?
Image courtesy of Kvikoo, Singapore
Our journey begins in the lively interiors of these establishments. In countries rich in nightlife, you’ll find a high concentration of pubs and bars – sometimes up to 150 per 100,000 people. Inside a pub in Hong Kong, for instance, noise levels can soar to 80 decibels during peak hours, akin to the din of city traffic. Even during ‘happy hours,’ the decibel count hovers around 75, still significant.
But let’s step outside these walls. Here, the story takes a different turn. In residential areas adjacent to these nightspots, the evening air is often filled with an unintended soundtrack: the persistent hum of nightlife. In a study from Macedonia, for instance, residents experienced noise levels of about 67 decibels in the evening – a consistent background murmur disrupting the peace of homes.
This issue isn’t just about sound; it’s about the voices of those affected. Residents’ complaints about noise pollution have become a chorus in many parts of the world, including the United Kingdom, Hong Kong, and Australia. These complaints highlight a pressing question: How can we maintain the lively spirit of our cities while respecting the need for quiet?
Governments and communities are tuning into this challenge. Their responses, colored by cultural and historical factors, range from strict regulations to innovative solutions. For example, in Hong Kong, efforts to control noise at its source, as detailed in a government booklet, showcase one way of striking a balance.
This is a story of harmony – finding a middle ground where the joyous buzz of pubs and bars coexists with the serene rhythm of residential life. It’s about understanding that in the symphony of city life, every note, from the loudest cheer to the softest whisper, plays a crucial role.
Brigham Young University, Provo, Utah, 84602, United States
Kent. L. Gee, Mark K. Transtrum, Shane V. Lympany
Popular version of 4aCA5 – Big data to streamlined app: Nationwide traffic noise prediction
Presented at the 184 ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0018816
VROOM! Vehicles are loud, and we hear them all the time. But how loud is it near your home, or at the park across town? The National Transportation Noise Map can’t give you more than an average daily sound level, even though it’s probably a lot quieter at night and louder during rush hour. So, we created an app that can predict the noise where, when, and how you want. How loud is it by that interstate at 3 AM, or at 5 PM? Using physics-based modeling, we can predict that for you. Why does the noise sound lower in pitch near the freeway than near other roads? Probably because of all the large trucks. How does the noise on your street during the winter compare to that across town, or on the other side of the country? Our app can predict that for you in a snap.
This (aptly named) app is called VROOM, for the Vehicular Reduced-Order Observation-based Model. It was made by using observed hourly traffic counts at stations across the country. It also uses information such as the average percentage of heavy trucks on freeways at night and the average number of delivery trucks on smaller roads on weekdays to predict sound characteristics across the nation. The app includes a user-friendly interface, and with only 700 MB of stored data can predict traffic noise for roads throughout the country, including near where you live. You don’t need a supercomputer to get a good estimate. The app will show you the sound levels by creating an interactive map so you can zoom in to see what the noise looks like downtown or near your home.