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Suggested future PhD Acoustics projects

Here are some project ideas we're currently interested in. Please click on the title for more details. This isn't an exhaustive list, so please contact us with your own ideas as well.

Noise, Viberation and Harshness (NVH) in Vehicles

Clever engineering is required in all vehicles nowadays to achieve passenger comfort whilst also minimising vehicle weight. Cars, buses, trains and ships all require diagnostic testing to help reduce noise and vibration generated by rolling on the road or track and mechanical components, engines, pumps etc.. Similar techniques are also needed in aircraft. In this PhD, new techniques will be developed for analysing multi-channel acoustic and vibration signals from vehicles in operation. This will improve analysis of how noise and vibration is generated and transmitted through the vehicle and lead to quieter vehicles and /or weight reductions. Candidates will need a good degree or Masters in Mechanical Engineering.

Contact a.t.moorhouse@salford.ac.uk

Acoustics Metamaterials for Engineering Noise Control

Metamaterials possess useful properties not found in naturally-occurring or other manmade materials. In metamaterials, the effective density and elastic moduli can attain negative values. When one of these quantities is negative, the medium does not support any propagating waves in a range of frequencies and there is a “stop band". This provides an opportunity of using them as nearly perfect compact noise screens. Few of the potential metamaterial noise control applications have been investigated so far. The proposed research will respond to the engineering challenge of finding lightweight materials for sound and vibration reduction particularly at low frequencies. The project will contribute particularly to the reduction of noise and vibration at frequencies below 250Hz since such low frequencies are attenuated less by walls and other structures in common constructions and can cause severe disturbance. As well as having many civilian applications, this is of military interest as metamaterials could be used as effective blast reflectors.

Contact o.umnova@salford.ac.uk

Rain noise is an important consideration nowadays in the design of schools, sports halls and many other buildings. A standard measurement method was introduced in 2006 (ISO 140:18 - based largely on research carried out at Salford during the early 1990s) which allows roof constructions to be characterised and rated in terms of their rain noise performance. The current rain noise research aims to extend earlier work so as to develop faster and more adaptable measurement methods as well as prediction models. It will also extend the ‘Rain Noise Simulator’, developed during various student projects; the simulator produces realistic simulated sounds of any type of rainfall falling on a roof tested in ‘dry’ conditions, i.e. without any real or artificial rainfall.

Contact a.t.moorhouse@salford.ac.uk

Conventional porous absorbers have poor low frequency performance unless very thick layers are used. This project focuses on the development of new porous absorbers which can overcome this limitation. Low frequency absorption can be improved by introducing two very different scales of the pores, however so far only very simplistic geometries have been studied. We would like to investigate whether the introduction of multiple scales (i.e. pores with more than two characteristic sizes) can dramatically improve performance. While materials with multiple pore scales are well known (e.g. vermiculite), their acoustical applications are currently limited. A general theoretical approach to modelling multi-scale porous structures needs to be developed. It will then be possible to identify and optimise those material parameters which are most important for the acoustical performance.

Contact o.umnova@salford.ac.uk

Rain noise is an important consideration nowadays in the design of schools, sports halls and many other buildings. A standard measurement method was introduced in 2006 (ISO 140:18 - based largely on research carried out at Salford during the early 1990s) which allows roof constructions to be characterised and rated in terms of their rain noise performance. The current rain noise research aims to extend earlier work so as to develop faster and more adaptable measurement methods as well as prediction models. It will also extend the ‘Rain Noise Simulator’, developed during various student projects; the simulator produces realistic simulated sounds of any type of rainfall falling on a roof tested in ‘dry’ conditions, i.e. without any real or artificial rainfall.

Contact a.t.moorhouse@salford.ac.uk

Conventional porous absorbers have poor low frequency performance unless very thick layers are used. This project focuses on the development of new porous absorbers which can overcome this limitation. Low frequency absorption can be improved by introducing two very different scales of the pores, however so far only very simplistic geometries have been studied. We would like to investigate whether the introduction of multiple scales (i.e. pores with more than two characteristic sizes) can dramatically improve performance. While materials with multiple pore scales are well known (e.g. vermiculite), their acoustical applications are currently limited. A general theoretical approach to modelling multi-scale porous structures needs to be developed. It will then be possible to identify and optimise those material parameters which are most important for the acoustical performance.

Contact o.umnova@salford.ac.uk

Despite the advance of visualisation and auralisation research over the last few decades, the fusing together of the two technologies is still unsatisfactory. What often happens is a world-class facility in one area (e.g. vision) has less than excellent facilities in the other (e.g. sound). This places severe limits on the realism VR simulations, the virtual environments they create, especially how immersive it is. At Salford we have been working to integrate auralization and visual simulations together for the last few years. We are about to complete a near million pounds upgrade on both our acoustic and visualization research facilities to create a infra-structure that would allow multi-modal virtual reality simulation with both world-class acoustics and visualisation. This PhD research project will use these upgraded facilities to address interfacing questions, as well as the impact of using different complexity of configurations on realism. The aim of the doctoral research would be to develop different integration strategies that can suit differing requirements of applications such as teleconferencing, virtual studios, and virtual workspaces.

Contact y.w.lam@salford.ac.uk

Some CDs sound great and some don’t: the sound quality of audio programme material is very variable. Expert and naïve listeners are quite good at picking up these differences in sound quality. However, so far there are no metrics that can quantify if a given music track is of good quality or not. This PhD project aims to define and extract quality features from audio signals that enable an automated rating of the acoustic quality therein. The technical aspects of the research project will be underpinned by a substantial study of human factors that determine perceived quality in sound and audio production. The foreseen outcomes are: 1) A framework that sets the relative importance of various objective acoustic measures of signal content in the context of human listening; 2) A digital tool that automatically rates and improves audio quality in a given stream. Applications of the knowledge and technology span from automated adjustment to different reproduction scenarios (eg: radio speech in a car vs. live sound) to archive recovery.

Contact B.M.Fazenda@salford.ac.uk

At the mixing stage in Audio Production, the professional option is to use expensive, specialist facilities. However, an increasing amount of sound production work gets done ‘on the move’ using laptops or working in offices. There is a need for better sound monitoring through headphones. Currently, headphone monitoring has its own inherent problems both in stereo and multichannel (e.g. 5.1) program presentation.

This PhD acoustics project proposes to develop a critical monitoring system for headphone reproduction. Research will investigate advanced digital signal processing techniques alongside a study of human listening factors to produce a system that enables sound engineering work outside a controlled studio environment. The outcomes of the doctoral project will result in hardware or software application crucial to the current trends of the sound production industry.

Contact B.M.Fazenda@salford.ac.uk

Reliable and fast methods of measuring sound insulation are vitally important for ensuring the quality of new buildings. However, the current measurement standards do not work well at low frequencies where most complaints occur. This doctoral research project will investigate novel measurement methods adapted for low frequencies that will complement existing standard methods. The research program will involve both theoretical and practical work and will draw on work carried out in numerous student projects. It will exploit the state-of-the-art laboratories at Salford and our 40 plus years of experience as an accredited laboratory for sound insulation measurement.

Contact a.t.moorhouse@salford.ac.uk

Diffusers are used to disperse sounds. In small rooms, such as studios, they smear early arriving reflections which otherwise could cause distortion. In larger spaces, such as auditoria, concert halls and theatres, they might be used to form stage or audience canopies to evenly distribute sound around the space. In the last few decades, many new types of diffusers have been developed, but still crucial aspects need researching. For instance, subjective testing is needed to evaluate the true perceptual worth of diffusers - such a phd could expand to develop binaural coloration measures which currently don't work well. Other doctorates could explore prediction and measurement methods for diffusers, for instance the former might research time domain methods while the latter might explore in-situ measurement techniques.

Contact t.j.cox@salford.ac.uk

Acoustic studies of ancient monuments is relatively scarce before the Greek and Roman eras when amphitheatres were central to these societies. Studies into the behaviour of sound in Neolithic archaeological sites show recurring and interesting acoustic effects, which would have been audible to our ancestors. Understanding the acoustics helps archaeologists and historians understand what the people using or constructing these places would have intended. This project intends to develop a methodology for a new area in archaeology and acoustics. The project involves the study of ancient sites around the world and includes measurements and modelling with room acoustic software, finite element analysis and wave based acoustic models.

Contact B.M.Fazenda@salford.ac.uk

Advances in technology (Bluetooth headsets, ‘iPods’, quieter cars, helmets) are leading to situations where an individual's perception of the surrounding environment is hindered, making him/her more vulnerable to accidents and/or intentional dangers. Examples include: a driver unaware of a fast moving emergency vehicle; a motorbike or cyclist wearing a protection helmet; a civil protection foraging robot or vehicle on patrol. This PhD research project aims to study and develop detection and warning systems for users or equipment, allowing constant sound monitoring of the environment and identification of potential threats. The project straddles across a set of multi-disciplinary skills such as sensor engineering (with particular emphasis on acoustic detection), digital signal processing and cognitive behaviour. The research and development of advanced acoustic sensor networks and associated signal acquisition and analysis would form the core of the doctorate. Collaboration with psychology and social sciences partners will be provided to support the areas of cognition and human behaviour.

Contact B.M.Fazenda@salford.ac.uk

Finger nails scrapping down a blackboard, the scream of a baby, your neighbour’s dog barking, someone throwing up: what is the worst sound in the world? In 2005/6 I ran a large scale web experiment to examine the worst sound in the world which attracted millions of votes. While the website has produced interesting results on people’s responses to the sounds, it is still unclear how valid the results are? In this phd research project, you will carry out perceptual measurements in the laboratory to compare to web experiment results, to determine the limitations of testing subjective responses over the Internet. Can the vast number of respondents available via the Internet compensate for the very uncontrolled experimental conditions?

Contact t.j.cox@salford.ac.uk

Understanding and utilising to best effect multiple sensory cues within virtual reality environments has been a focus of much ongoing research. Of particular interest to the us is the assessment of mediated aural cues within a wider multi-sensoral context. Such work is being facilitated by Salford University’s two in-house developed 256 wavefield synthesis systems and their associated API. The faithful rendering of virtual acoustic environments is comprised by the limitations of acoustic and visual mediating systems and their host environment. However, there is much scope for investigating and hence optimising pathological cue rejection and desired cue consolidation.

Contact Ian Drumm

The amplitude modulated sound character of wind turbines is frequently mentioned in the context of annoyance and health effects with significant economic impact. While there are still questions about the source mechanisms and characterisation of amplitude modulation one of the most under-researched areas is the response of listeners to this type of sound. Preliminary listening tests have been conducted by the University of Salford but more work needs to be done to understand most suitable metrics and the effects of random occurrence and long term exposure.

Contact Sabine von Hünerbein

Recent research has shown that soundscapes are important in defining the character of a place or scene and in influencing the perceived quality. Unfortunately, soundscape has not always been a fully integral part of modern urban city planning, where visual aesthetics and material sustainability dominate. Usually only a noise pollution, is considered, which is a small and extreme part of the soundscape. This project will attempt to change this by looking at the impact of soundscape in urban regeneration scenarios. Virtual audio and visual rendering will be used together to create virtual reality (VR) simulations. Human responses to these will then be tested to determine if a significant change of attitude can be effected by changing the soundscape.

Contact y.w.lam@salford.ac.uk

Growing concerns about climate change have led to an increased interest and investment in the development and deployment of low carbon technologies.

Wind farms are now ubiquitous as a sustainable method for harvesting wind energy. Due to the availability of adequate area and levels of nuisance to human environment, these are commonly deployed in remote sites and off-shore locations where monitoring and maintenance of units is typically costly. Remote acoustic monitoring presents advantages that could provide an efficient solutions. An independent and remote system, i.e not mounted on the turbine, is able to monitor various elements of a turbine and detect various types of fault from the sound emitted by the turbines. This PhD project aims to research methods to extract a wind turbine’s acoustic signature and, by advanced analysis, determine the condition of its various components. Signal detection and analysis techniques will be a starting point, although more advanced techniques such as blind source separation and machine learning methods will also be part of the doctoral research.

Contact B.M.Fazenda@salford.ac.uk