Centre for Marine Science and Technology, Curtin University, Bentley, Western Australia, 6102, Australia
Benjamin Saunders
School of Molecular and Life Sciences
Curtin University
Bentley, Western Australia, Australia
Christine Erbe, Iain Parnum, Chong Wei, and Robert McCauley
Centre for Marine Science and Technology
Curtin University
Bentley, Western Australia, Australia
Popular version of 5aAB6 – The search to identify the fish species chorusing along the southern Australian continental shelf
Presented at the 185 ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023649
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
Unknown fish species are singing in large aggregations along almost the entire southern Australian continental shelf on a daily basis, yet we still have little idea of what species these fish are or what this means to them. These singing aggregations are known as fish choruses, they occur when many individuals call continuously for a prolonged period, producing a cacophony of sound that can be detected kilometres away. It is difficult to identify fish species that chorus in offshore marine environments. The current scientific understanding of the sound-producing abilities of all fish species is limited and offshore marine environments are challenging to access. This project aimed to undertake a pilot study which attempted to identify the source species of three fish chorus types (shown below) detected along the southern Australian continental shelf off Bremer Bay in Western Australia from previously collected acoustic recordings.
Each fish chorus type occurred over the hours of sunset, dominating the soundscape within unique frequency bands. Have a listen to the audio file below to get a feeling for how noisy the waters off Bremer Bay become as the sun goes down and the fish start singing. The activity of each fish chorus type changed over time, indicating seasonality in presence and intensity. Chorus I and II demonstrated a peak in calling presence and intensity over late winter to early summer, while Chorus III demonstrated peak calling over late winter to late spring. This informed the sampling methodology of the pilot study, and in December 2019, underwater acoustic recorders and unbaited video recorders were deployed simultaneously on the seafloor along the continental shelf off Bremer Bay to attempt to collect evidence of any large aggregations of fish species present during the production of the fish choruses. Chorus I and the start of Chorus II were detected on the acoustic recordings, corresponding with video recordings of large aggregations of Red Snapper (Centroberyx gerrardi) and Deep Sea Perch (Nemadactylus macropterus). A spectrogram of the acoustic recordings and snapshots from the corresponding underwater video recordings are shown below.
The presence of large aggregations of Red Snapper present while Chorus I was also present was of particular interest to the authors. Previous dissections of this species had revealed that Red Snapper possessed anatomical features that could support sound production through the vibration of their swimbladder using specialised muscles. To explore this further, computerized tomography (CT) scans of several Red Snapper specimens were undertaken. We are currently undertaking 3D modelling of the sound-producing mechanisms of this species to compute the resonance frequency of the fish to better understand if this species could be producing Chorus I.
Listening to fish choruses can tell us about where these fish live, what habitats they use, their spawning behaviour, their feeding behaviour, can indicate their biodiversity, and in certain circumstances, can determine the local abundance of a fish population. For this information to be applied to marine spatial planning and fish species management, it is necessary to identify which fish species are producing these choruses. This pilot study was the first step in an attempt to develop an effective methodology that could be used to address the challenging task of identifying the source species of fish choruses present in offshore environments. We recommend that future studies take an integrated approach to species identification, including the use of arrays of hydrophones paired with underwater video recorders.
Council for Scientific and Industrial Research, Council for Scientific and Industrial Research, Gauteng, 0001, South Africa
Popular version of 3pAAb – Classroom acoustics: a case study of the cost-benefit of retrofitted interventions
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023323
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
Achieving the right acoustic conditions for classrooms is often dismissed by school planners as being too difficult or too expensive. This is to the detriment of students who are unable to hear the teacher properly, especially for children who are being taught in their second language, as is common in South Africa. This study proves that acoustic treatment need not be difficult or costly to achieve.
To refute the notion that acoustic improvements are expensive and specialized, this experimental case study was designed and carried out in a typical classroom in the small rural village of Cofimvaba in the Eastern Cape, South Africa. The ideal classroom environment has a low ambient noise level of 35 dB and a reverberation time below 0.7 seconds, but this classroom has a reverberation time of 1 second. Reverberation time refers to the time it takes for a noise to die down and essentially refers to how much a room echoes, which negatively affects speech clarity. The experimental intervention simulated the installation of floating ceiling islands by installing different materials on the roof of temporary gazebos in the classroom.
The four materials used were acoustic ceiling tiles which represent a typical solution and three DIY solutions using carboard egg cartons, thermal insulation batting, and sponge foam bed mattresses. Each material provided an improved reverberation time. The best performing was the sponge at 0.6 seconds, while the other three materials performed equally at 0.8 seconds.
The cost of each material was reduced to a rate per square meter. The most expensive material was the acoustic ceiling tiles at R 363.85/m2 while the cheapest was the egg cartons at R 22.22/m2, or less if they are available as waste items.
The availability of materials was evaluated in terms of the distance to supply and whether the product is available in a retail store or requires a special order and delivery. The batting is available from hardware stores nationwide and could be purchased by walk-in from the local hardware store, within a 2 km radius of the site. The egg cartons could be ordered online and delivered from a packaging company within a 150 km radius. The foam mattresses could be purchased by walk-in at a local retailer within a 5 km radius of the site. The acoustic ceiling tiles were ordered online and delivered from the warehouse within a 700 km radius of the site.
Using the weighted sum model and assigning equal weighting to each attribute of acoustic performance, cost, distance to supply, and walk-in availability, a performance score for each intervention material was calculated. The batting ranked number one, followed in order by the sponge, egg cartons and lastly acoustic tiles.
The case study demonstrates that an improvement in acoustic conditions of at least a 0.2 second reduction in reverberation time can be achieved without significant cost. Although the batting did not achieve the ideal reverberation time, when only the speech frequencies were considered, it fell within the recommended maximum of 0.7 seconds.
The recommended design intervention is a frame containing batting covered with a taught fabric and suspended from ceiling hooks, thus avoiding disruptive construction works. This shows that improved classroom acoustics can be achieved without high cost or technical difficulty.
Centre for Marine Science and Technology, Curtin University, Bentley, WA, 6102, Australia
David Dall’Osto
Applied Physics Laboratory
University of Washington
Seattle, Washington
United States
Popular version of 1pAO2 – Long-range underwater acoustic detection of aircraft surface impacts – the influence of acoustic propagation conditions and impact parameters
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0022761
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
In the right circumstances, sound can travel thousands of kilometres through water, so when Malaysian Airlines flight MH370 went missing in the Indian Ocean in 2014 we searched recordings from underwater microphones called hydrophones for any signal that could be connected to that tragic event. One signal of interest was found, but when we looked at it more carefully it seemed unlikely to be related to the loss of the aircraft.
Fast-forward five years and in 2019 the fatal crash of an F35 fighter aircraft in the Sea of Japan was detected by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) using hydrophones near Wake Island, in the north-western Pacific, some 3000 km from the crash site1.
Fig. 1. Locations of the F35 crash and the CTBTO HA11N hydroacoustic station near Wake Island that detected it.
With the whereabouts of MH370 still unknown, we decided to compare the circumstances of the F35 crash with those of the loss of MH370 to see whether we should change our original conclusions about the signal of interest.
Fig. 2. Location of the CTBTO HA01 hydroacoustic station off the southwest corner of Australia. The two light blue lines are the measured bearing of the signal of interest with an uncertainty of +/- 0.75 degrees.
We found that long range hydrophone detection of the crash of MH370 is much less likely than that of the F35, so our conclusions still stand, however there is some fascinating science behind the differences.
Fig. 3. Top: comparison of modelled received signal strengths versus distance from the hydrophones for the MH370 and F35 cases. Bottom: water depth and deep sound channel (DSC) axis depth along each path.
Aircraft impacts generate lots of underwater sound, but most of this travels steeply downward then bounces up and down between the seafloor and sea surface, losing energy each time, and dying out before it has a chance to get very far sideways. For long range detection to be possible the sound must be trapped in the deep sound channel (DSC), a depth region where the water properties stop the sound hitting the seabed or sea surface. There are two ways to get the sound from a surface impact into the DSC. The first is by reflections from a downward sloping seabed, and the second is if the impact occurs somewhere the deep sound channel comes close to the sea surface. Both these mechanisms occurred for the F35 case, leading to very favourable conditions for coupling the sound into the deep sound channel.
Fig. 4. Sound speed and water depth along the track from CTBTO’s HA11N hydroacoustic station (magenta circle) to the estimated F35 crash location (magenta triangle). The broken white line is the deep sound channel axis.
We don’t know where MH370 crashed, but the signal of interest came from somewhere along a bearing that extended northwest into the Indian Ocean from the southwest corner of Australia, which rules out the second mechanism, and there are very few locations along this bearing where the first mechanism would come into play.
Fig. 5. Sound speed and water depth in the direction of interest from CTBTO’s HA01 hydroacoustic station off Cape Leeuwin, Western Australia (magenta circle). The broken white line is the deep sound channel axis.
This analysis doesn’t completely rule out the signal of interest being related to MH370, but it still seems less likely than it being due to low-level seismic activity, something that results in signals at HA01 from similar directions about once per day.
[1] Metz D, Obana K, Fukao Y, “Remote Hydroacoustic Detection of an Airplane Crash”, Pure and Applied Geophysics, 180 (2023), 1343-1351. https://doi.org/10.1007/s00024-022-03117-6
Arup, L5 Barrack Place 151 Clarence Street, Sydney, NSW, 2000, Australia
Additional authors: Mitchell Allen (Arup) , Kashlin McCutcheon
Popular version of 3aSP4 – Development of a Data Sonification Toolkit and Case Study Sonifying Astrophysical Phenomena for Visually Impaired Individuals
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023301
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
Have you ever listened to stars appearing in the night sky?
Acousticians at Arup had the exciting opportunity to collaborate with astrophysicist Chris Harrison to produce data sonifications of astronomical events for visually impaired individuals. The sonifications were presented at the 2019 British Science Festival (at a show entitled A Dark Tour of The Universe).
There are many sonification tools available online. However, many of these tools require in-depth knowledge of computer programming or audio software.
The researchers aimed to develop a sonification toolkit which would allow engineers working at Arup to produce accurate representations of complex datasets in Arup’s spatial audio lab (called the SoundLab), without needing to have an in-depth knowledge of computer programming or audio software.
Using sonifications to analyse data has some benefits over data visualisation. For example:
Humans are capable of processing and interpreting many different sounds simultaneously in the background while carrying out a task (for example, a pilot can focus on flying and interpret important alarms in the background, without having to turn his/her attention away to look at a screen or gauge),
The human auditory system is incredibly powerful and flexible and is capable of effortlessly performing extremely complex pattern recognition (for example, the health and emotional state of a speaker, as well as the meaning of a sentence, can be determined from just a few spoken words) [source],
and of course, sonification also allows visually impaired individuals the opportunity to understand and interpret data.
The researchers scaled down and mapped each stream of astronomical data to a parameter of sound and they successfully used their toolkit to create accurate sonifications of astronomical events for the show at the British Science Festival. The sonifications were vetted by visually impaired astronomer Nicolas Bonne to validate their veracity.
Information on A Dark Tour of the Universe is available at the European Southern Observatory website, as are links to the sonifications. Make sure you listen to stars appearing in the night sky and galaxies merging! Table 1 gives specific examples of parameter mapping for these two sonifications. The concept of parameter mapping is further illustrated in Figure 1.
Table 1
Figure 1: image courtesy of NASA’s Space Physics Data Facility
Associate – Acoustics and Vibration, SLR Consulting Australia Pty Ltd, Melbourne, Victoria, 3002, Australia
Aaron McKenzie
Technical Director – Acoustics and Vibration
SLR Consulting Australia Pty Ltd
Susan Kay
Senior Program Environment Advisor – Acoustics
Australian Rail Track Corporation
Popular version of 1pNSb3 – Rail Noise Across Three States in Australia – Operational Noise Assessment on Inland Rail
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0022808
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
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.
Each fish chorus type occurred over the hours of sunset, dominating the soundscape within unique frequency bands. Have a listen to the audio file below to get a feeling for how noisy the waters off Bremer Bay become as the sun goes down and the fish start singing. The activity of each fish chorus type changed over time, indicating seasonality in presence and intensity. Chorus I and II demonstrated a peak in calling presence and intensity over late winter to early summer, while Chorus III demonstrated peak calling over late winter to late spring. This informed the sampling methodology of the pilot study, and in December 2019, underwater acoustic recorders and unbaited video recorders were deployed simultaneously on the seafloor along the continental shelf off Bremer Bay to attempt to collect evidence of any large aggregations of fish species present during the production of the fish choruses. Chorus I and the start of Chorus II were detected on the acoustic recordings, corresponding with video recordings of large aggregations of Red Snapper (Centroberyx gerrardi) and Deep Sea Perch (Nemadactylus macropterus). A spectrogram of the acoustic recordings and snapshots from the corresponding underwater video recordings are shown below.
Achieving the right acoustic conditions for classrooms is often dismissed by school planners as being too difficult or too expensive. This is to the detriment of students who are unable to hear the teacher properly, especially for children who are being taught in their second language, as is common in South Africa. This study proves that acoustic treatment need not be difficult or costly to achieve.
Fig. 1. Locations of the F35 crash and the CTBTO HA11N hydroacoustic station near Wake Island that detected it.
Fig. 2. Location of the CTBTO HA01 hydroacoustic station off the southwest corner of Australia. The two light blue lines are the measured bearing of the signal of interest with an uncertainty of +/- 0.75 degrees.
Fig. 3. Top: comparison of modelled received signal strengths versus distance from the hydrophones for the MH370 and F35 cases. Bottom: water depth and deep sound channel (DSC) axis depth along each path.
Fig. 4. Sound speed and water depth along the track from CTBTO’s HA11N hydroacoustic station (magenta circle) to the estimated F35 crash location (magenta triangle). The broken white line is the deep sound channel axis.
Fig. 5. Sound speed and water depth in the direction of interest from CTBTO’s HA01 hydroacoustic station off Cape Leeuwin, Western Australia (magenta circle). The broken white line is the deep sound channel axis.
Image courtesy of NASA & ESA; CC BY 4.0
Table 1
Figure 1: image courtesy of NASA’s Space Physics Data Facility
image courtesy of inlandrail.com.au