Busting the myth that new violins sound better after a period of “playing-in”

Andy Piacsek – andy.piacsek@cwu.edu

Central Washington University, Department of Physics, Ellensburg, WA, 98926, United States

Seth Lowery
Ph.D. candidate, University of Texas
Dept. of Mechanical Engineering
Austin, TX

Popular version of 4pMU3 – An experiment to measure changes in violin instrument response due to playing-in
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023547

How is a violin like a pair of hiking boots? Many violinists would respond “They both improve with use.” Just as boots need to be “broken in” by being worn several times to make them more supple, many musicians believe that a new violin, cello, or guitar, needs to be “played in” for a period of time, typically months, in order to fully develop its acoustic properties. There is even a commercial product, the Tone-Ritethat is marketed as a way to accelerate the playing-in process, with the claim of dramatically increasing “resonance, balance, and range,” and some builders of stringed instruments, known as luthiers, provide a service of pre-playing-in their instruments, using their own methods of mechanical stimulus, prior to selling them. But do we know if violins actually improve with use?

We tested the hypothesis that putting vibrational energy into a violin will, over time, change how the violin body responds to the vibration of the strings, which is measured as the frequency response. We used three violins in our experiment: one was left alone, serving as a control, while the two test violins were “played” by applying mechanical vibrations directly to the bridge. One of the mechanical sources was the Tone Rite, the other was a shaker driven with a signal created from a Vivaldi violin concerto as shown in the video below. The total time of vibration exceeded 1600 hours, equivalent to ten months of being played six hours per day.

Approximately once per week, we measured the frequency response of all three violins using two standard methods: bridge admittance, which characterizes the vibration of the violin body, and acoustic radiativity, which is based on the sound radiated by the violin. The measurement set up is illustrated in Figure 1.

Figure 1: Measuring the frequency response of a violin in an anechoic chamber.

Having a control violin allowed us to account for factors not associated with playing-in, such as fluctuating environmental conditions or simple aging, that might affect the frequency response. If mechanical vibrations had the hypothesized effect of physically altering the violin body, such as creating microcracks in the wood, glue, or varnish, and if the result were an increase in “resonance, balance, and range”, then we would expect a noticeable and cumulative change in the frequency response of the test violins compared to the control violin.

We did not observe any changes in the frequency responses of the violins that correlate with the amount of vibration. In Figure 2a, we plot a normalized difference in the bridge admittance between the two test violins and the control violin; Figure 2b shows a similar plot for the acoustic radiativity.

In both plots, we see no evidence that the difference between the test violins and the control violin increases with more vibration; instead we see random fluctuations that can be attributed to the slightly different experimental conditions of each measurement. This applies to both the Tone-Rite, which vibrates primarily with the 60 Hz frequency of the electric power it is plugged into, and the shaker, which provided the same frequencies that a violinist practicing her instrument would create.

Our conclusion is that long term vibrational stimulus of a violin, whether achieved mechanically or by actual playing, does not produce a physical change in the violin body that could affect its tonal characteristics.

The expected sonic transformation of the Arctic Ocean under Climate Change

Giacomo Giorli – Giacomo.Giorli@cmre.nato.int

NATO STO CMRE, Viale S. Bartolomeo, 400, La, Spezia, 19126, Italy

Aniello Russo
La Spezia, Italy

Sandro Carniel
La Spezia, Italy

Popular version of 2pAO2 – Noise levels in a changing Arctic Ocean and its implications for security
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023028

Global warming is rapidly driving a substantial transformation of the oceanographic characteristic of the Arctic Ocean and its cryosphere. The Arctic region is in fact warming up much faster than the rest of the planet, and recent studies and reports have highlighted its major consequences. In much of the ice-free Arctic Ocean, the mean sea surface temperature continued its warming trend observed since 1982 and ice sheets in Greenland receded for the 25th consecutive year. According to NASA reports, this year the annual sea-ice minimum extent was the sixth lowest on record. Such an observation implies a significant sea ice retreat and reduction of ice longevity, which will most likely turn the future Arctic in a giant Marginal Ice Zone. Storm and rain patterns are also changing, having Arctic precipitations significantly increased since the 1950s across all seasons. Moreover, increased heat fluxes injected by  warmer Atlantic waters  are preventing the formation of new ice, as well as reducing the thickness and longevity of multi-year ice. The resulting atmosphere- ocean interactions under these new forcing create more turbulent mixing (heat) between the deep Atlantic waters and the upper Arctic Ocean, hence a positive feedback mechanism usually referred to as “Atlantification”, that is, a climatic shift driving the Arctic Ocean towards new and different oceanographic characteristics. Moreover, an ice-free Arctic will open up new possibilities for deep-sea resources extraction, new commercial and military routes and activities. All these environmental modifications are already affecting the Arctic Ocean underwater soundscape. An example is provided by the underwater noise at low frequencies, expected to increase due to the openings of new routes for maritime shipping resulting from nearly ice-free seas (Figure 1). In addition, the more frequent storms and intense precipitation would affect the sea state generating bubbles and spray associated with breaking waves, hence increasing the underwater noise. Additional contributions are due to changes affecting marine life, marine food industries and coastal economies.

Figure 1: Main maritime routes across the Arctic Ocean with minimum sea ice extension. Source: US Navy Arctic Roadmap 2014-2030.

In the lights of this ongoing transformation of the Arctic, CMRE conducted a series of studies and sea-trials (funded by the NATO Allied Command Transformation) of the new Arctic oceanographic conditions and ambient noise. In 2021 and 2022, a series of moorings equipped with passive acoustic recorders and oceanographic sensors were deployed in the region of Fram Strait. In 2023, with the additional support of the NATO Office of the Chief Scientist, CMRE started a long-term scientific endeavor to address how climate change might affect the Alliance’s security in the maritime domain. In June-July 2023, CMRE deployed three deep moorings for monitoring the acoustic-oceanographic conditions in the long term.

Results contribute to create a long-term database of acoustic measurements and to understanding how sounds from different sources (biological, man-made and natural) will change in the next decade.

Consumer label for the noise properties of tires and road pavements

Ulf Sandberg – ulf.sandberg@vti.se

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.

Curtains and drapes that can reduce noise pollution by more than half

Ben Cazzolato – benjamin.cazzolato@adelaide.edu.au

The University of Adelaide, Adelaide, SA, 5005, Australia

Cameron West
Acoustic Blinds and Curtains
Sydney, New South Wales, Australia

Tyler Schembri
The University of Adelaide
Forestville, South Australia, Australia

Peter Watkins
Acoustic Blinds and Curtains
Sydney, New South Wales, Australia

Will Robertson
The University of Adelaide
Forestville, South Australia, Australia

Popular version of 2pAA3 – Enhancing acoustic comfort with window coverings: Reducing sound transmission and reverberation times with a single product
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023007

Noise pollution isn’t just a nuisance, it’s bad for your health. Prolonged noise exposure has been linked to several short and long-term health problems – both physiological and psychological. The World Health Organization has estimated an annual loss of “at least one million healthy years of life” due to traffic noise alone.

Traditionally curtains and drapes have been used for design and light control only. However, they also present a great opportunity for a comprehensive acoustic treatment. This is for a number of reasons:

  1. They are installed over windows and glazing, which is where the sound commonly enters spaces;
  2. Windows generally have a significant surface area and are typically very reflective, which presents an opportunity to remove noise via absorption when covered;
  3. Unlike other acoustic treatments, they are a natural fit in most modern spaces allowing architects, designers and clients freedom in their design unconstrained by acoustics.

Extensive testing by qualified acoustic engineers in the Acoustic and Vibration Laboratories at the University of Adelaide, Australia have shown that it is possible to reduce noise pollution by more than half* with an acoustic interlining. The acoustic interlining is a mass layer that is sandwiched between two sound absorbing curtain fabrics. Together these layers block and absorb sound.

Figure 1: Measuring the sound transmission loss and sound absorption of an acoustic curtain in a reverberation chamber at the University of Adelaide.

The acoustic interlining was tested over four glazing conditions; open window, 4mm glass, 6.38mm glass and 10.38mm glass, across 15 different curtain configurations, totalling 76 tests. The plot below shows the reduction in sound pressure level in a receiving room when using a typical acoustic curtain as a room divider. In the plot we compare only using the interlining, using only the face fabrics, and the benefit of combining both face fabrics and interlining, with the latter providing a frequency-weighted improvement of 17dB. Similar results were obtained when the tests were repeated for the three thicknesses of glazing.

Figure 2: Reduction in sound pressure level (known as the level difference improvement) when using the acoustic curtains as a room divider.

We have generated two audio files demonstrating how these acoustic curtains reduce noise pollution: Room divider application using 1500gsm interlining, and 800gsm interlining over 4mm glazing applied to traffic noise.

Visit the Acoustic Blinds and Curtains website for more details on the curtain construction and informative videos demonstrating how these curtains reduce noise pollution and improve room acoustics.

Our testing has shown how curtains and drapes can reliably reduce noise pollution by more than half for both open and closed windows. This is a game-changer for architects and end-users looking for simple, cost effective noise reduction and sound absorption compared to other acoustic products and offer a functional alternative to traditional blinds and curtains.

*perceived noise reduction

Rocket noise: What does it mean for Australian spaceports?

Kent L. Gee – kentgee@byu.edu
Twitter (x): @KentLGee
Instagram: @gee.kent

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

Daniel Edgington-Mitchell
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.

Let’s go soundwalking!

David Woolworth – dwoolworth@rwaconsultants.net

Roland, Woolworth & Associates, Oxford, MS, 38655, United States

Bennett Brooks and Brigitte Schulte-Fortkamp

Popular version of 4pAAb1 – Introduction to Soundwalking – an important part of the soundscape method
Presented at the 185th ASA Meeting
Read the abstract at https://eppro01.ativ.me/web/index.php?page=IntHtml&project=ASAFALL23&id=3589830

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.

Figure 1

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.

Figure 2

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.

Figure 3

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.

Figure 4