Jordan Cheer

Jordan Cheer
University of Southampton · Institute of Sound and Vibration Research (ISVR)

PhD

About

156
Publications
34,093
Reads
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1,552
Citations
Introduction
Jordan Cheer currently works at the Institute of Sound and Vibration Research (ISVR), University of Southampton. He works on the active control of sound and vibration and sound field control for audio reproduction.
Additional affiliations
March 2017 - present
University of Southampton
Position
  • Professor (Associate)

Publications

Publications (156)
Article
The active control of sound fields has been widely applied in both active noise control and sound field reproduction, however, relatively few studies have focused on active acoustic cloaking. In order to build upon the knowledge and understanding in the areas of active noise control and sound field reproduction, this paper investigates the correspo...
Article
The broadband control of noise and vibration using multi-input, multi-output (MIMO) active control systems has a potentially wide variety of applications. However, the performance of MIMO systems is often limited in practice by high computational demand and slow convergence speeds. In the somewhat simpler context of single-input, single-output broa...
Article
A general formulation is presented for the optimum controller in an active system for local sound control in a spatially random primary field. The sound field in a control region is selectively attenuated using secondary sources, driven by reference sensors, all of which are potentially remote from this control region. It is shown that the optimal...
Article
This paper considers the active control of road noise in vehicles, using either multichannel feedback control, with both headrest and floor positioned microphones providing feedback error signals, or multichannel feedforward control, in which reference signals are provided by the microphones on the vehicle floor and error signals are provided by th...
Article
As well as being able to reproduce sound in one region of space, it would be useful to reduce the level of reproduced sound in other spatial regions, with a “personal audio” system. For mobile devices this is motivated by issues of privacy for the user and the need to reduce annoyance for other people nearby. Such personal audio systems can be real...
Article
Full-text available
Acoustic black holes (ABHs) can provide effective damping of the reflected wave component when used to terminate a beam. The behaviour of an ABH is characterised by its local modes, which produce narrow frequency bands of high absorption. To enhance the performance of ABH terminations, a multi-taper ABH has previously been proposed and analytical r...
Article
Multi-reference feedforward Active Noise Control (ANC) has been shown to provide increased noise mitigation capability in ANC headphones compared to a single reference feedforward controllers, due to the availability of additional time advanced information. Recent studies have also shown that the integration of a single-reference feedforward contro...
Article
Tapered elastic wedges can be used to control flexural vibrations and this article explores a method of enhancing the performance of such terminations using multiple wedges. A system design where a uniform beam is terminated by multiple quadratically tapered wedges of different lengths is proposed, aiming to enhance the absorption of flexural vibra...
Article
Full-text available
Nonreciprocal acoustic devices typically break reciprocity by introducing nonlinearities or directional biasing. However, these devices are generally not fully adaptable and often use resonant cavities, which only exhibit nonreciprocal behaviour over a narrow bandwidth. Therefore, to overcome these challenges, this paper investigates how wave-based...
Conference Paper
Full-text available
Membrane-type acoustic metamaterials (MAM) consist of a thin pre-stretched membrane with masses periodically attached to the membrane. MAM can be designed to be very lightweight and exhibit anti-resonances at low frequencies with sound transmission loss values that can be much higher than the mass-law. This makes MAM very appealing for different no...
Article
Full-text available
Acoustic black holes (ABHs) are tapered structural features that can achieve high levels of structural damping within lightweight constraints. It has previously been proposed to integrate feedforward active vibration control into an ABH to enable control over a broad spectrum, however, the time-advanced information required in this control strategy...
Article
Full-text available
Acoustic Black Holes (ABHs) are structural features that can be embedded into plates to provide effective structural damping. However, the performance of an embedded ABH is limited by its size, which determines the ABH cut-on frequency. It is not always practicable to increase the size of an ABH to reduce its cut-on frequency, however, previous wor...
Article
This paper presents a design approach for a shunted electrodynamic metamaterial (EDMM) for broadband robust vibration control. A unit cell of 12 inertial electrodynamic transducers is proposed, where the response of each transducer is tuneable via a connected resistive and inductive shunt circuit. The variations in the parameters of an off-the-shel...
Article
Personal sound zones (PSZ) systems use an array of loudspeakers to render independent audio signals to multiple listeners within a room. The performance of a PSZ system, designed using weighted pressure matching, depends on the selected target responses for the bright zone. In reverberant environments, the target responses are generally chosen to b...
Article
Full-text available
Pass-by noise contribution analysis is an engineering procedure employed to estimate the contributions from various noise sources on a vehicle to the overall sound pressure level. This can be realised by placing a set of microphones close to the various sources to estimate their source strengths and then synthesising the response at a far-field lin...
Article
No PDF available ABSTRACT Active control systems are often used to surmount the challenges associated with using passive control measures to control low frequencies, since they achieve control without the application of large or heavy control treatments. Historically, linear active control strategies have been used in feed-forward control systems t...
Article
A private sound zone can be created by focusing a spoken message towards a target listener using a loudspeaker array. In practice, however, the reproduced speech cannot be completely contained within the target zone due to practical limits on the directivity of the array. Despite these limitations, the privacy of the message can be maintained if th...
Conference Paper
Full-text available
There has been significant interest in the design of nonreciprocal acoustic devices that allow acoustic waves to be perfectly transmitted in one direction, whilst the acoustic waves propagating in the opposite direction are blocked or reflected. Previously proposed nonreciprocal acoustic devices have broken the symmetry of transmission by introduci...
Article
Resonant structural vibrations are a common source of disruptive noise, and suppressing these vibrations is often the most direct way to reduce the noise levels. Elastic metamaterials (EMMs) consist of distributed resonant substructures, at a scale which is small compared to the wavelength of vibration. This allows these materials to be used in app...
Conference Paper
Full-text available
p>Resonant structural vibrations are a common source of disruptive noise, and suppressing these vibrations is often the most direct way to reduce the noise levels. Elastic metamaterials (EMMs) consist of distributed resonant substructures, at a scale which is small compared to the wavelength of vibration. This allows these materials to be used in a...
Conference Paper
Full-text available
Recent interest has arisen in the realisation of nonreciprocal acoustic devices that achieve unidirectional sound transmission. In other words, these devices allow perfect transmission from waves travelling in one direction, whilst blocking waves travelling in the opposite direction. These devices have thus been described as the acoustic analogue o...
Conference Paper
Full-text available
The current paper considers the case of a locally-reacting, uniform spherical scatterer in a homoge-neous fluid, subjected to a monochromatic acoustic plane-wave incidence. The scattering behaviour is controlled with a single point-monopole acoustic secondary source on the surface of the sphere. Firstly, scattered sound power is reduced by ‘least m...
Conference Paper
Full-text available
An elegant theory of acoustic scattering has been formulated by Bobrovnitskii in terms of three sep-arate impedance matrices, corresponding to the structural response of the scattering body, the inter-nal acoustic response of the space of the scattering body if filled with fluid, and the external sound radiation from the scattering body into the su...
Article
This paper investigates the effect of changes in the environment on the performance of two widely-used virtual sensing methods for active noise control (ANC): the remote-microphone method and the additional-filter method. Robust performance of adaptive feedforward control algorithms incorporating such virtual sensing techniques is essential to achi...
Article
No PDF available ABSTRACT Pipe-like structures are utilised in a wide variety of engineering applications, which must often consider the impact of noise and vibration. This paper presents a numerical study into the Vortex Induced Vibration (VIV) of a flexible pipe in laminar flow and the resulting acoustic radiation, and explores the potential of a...
Article
Full-text available
Acoustic Black Holes (ABHs) are structural features that are typically realised by introducing a tapering thickness profile into a structure that results in local regions of wave-speed reduction and a corresponding enhancement in the structural damping. In the ideal theoretical case, where the ABH tapers to zero thickness, the wave-speed reaches ze...
Chapter
Active sound control has seen extensive use in a variety of industries and has been a potential tool for noise and vibration control engineers in the automotive industry since the late 1980s. However, it has only relatively recently begun to be more widely adopted within the automotive sector. This is in part due to a reduction in the cost of imple...
Article
Full-text available
The use of virtual sensing allows the frequency range of a local active noise control system located close to a listener's ears to be extended beyond what is possible when only controlling from remote physical sensors, particularly if head tracking is also used to determine the position of the virtual sensors. As the frequency range is extended, ho...
Conference Paper
Acoustic black holes (ABHs) are tapered structural features that can achieve high levels of structural damping within lightweight constraints. It has previously been proposed to integrate feedforward active vibration control into an ABH to enable control over a broad spectrum, however, the time advance information required in this control strategy...
Conference Paper
Full-text available
Personal audio refers to the production of spatially distinct listening zones within a space that is shared by multiple people. This technology can enable each listener to hear their own desired material without affecting others, facilitate private communication in public spaces, or provide independent volume controls when people of different ages...
Conference Paper
Full-text available
Acoustic cloaking is an area of significant research interest, as the ability to minimise the effect that an object has on its enclosing soundfield has potential applications in architectural acoustics and underwater acoustics. The use of active control as an acoustic cloaking strategy has been presented previously in the literature, and both simul...
Conference Paper
Full-text available
Acoustic Black Holes (ABHs) have been demonstrated as an effective and particularly lightweight passive vibration control solution. They are able to achieve a high level of structural damping with a thin layer of concentrated damping material by introducing a reduction in the structural wave speed. This is generally achieved by introducing a geomet...
Conference Paper
Acoustic black holes (ABHs) are commonly realised as structural features that can be used for effective lightweight damping. Passive damping material can be added to the taper to enhance the performance. This paper presents an experimental investigation into a hybrid damping solution consisting of an ABH on one end of a beam with a piezoelectric pa...
Conference Paper
Full-text available
The purpose of this paper is to investigate an alternative microphone array configuration to the standard linear array for indoor pass-by noise (PBN) measurement. Indoor PBN measurement allows for vehicle noise to be measured with a higher level of control and repeatability than exterior PBN measurements (ISO 362-1:2015). The interior measurement t...
Article
Warning sound systems for electric vehicles with advanced beamforming capabilities have been investigated in the past. Despite showing promising performance, such technologies have yet to be adopted by the industry, as implementation costs are generally too high, and the components too fragile for implementation. A lower cost solution with higher d...
Article
Full-text available
Active Structural Acoustic Control (ASAC) is mostly performed using a passive noise barrier, vibration actuators, sensors and a control system. ASAC reduces or alters the vibration of the barrier structure in a way that blocks the noise propagation through it. However, it is crucial that the actuators are appropriately arranged to be able to e↵ecti...
Article
Full-text available
The ability to acoustically cloak an object, effectively making the object acoustically invisible to an outside observer, is of interest in many applications where the presence of an object has an undesirable impact on the sound-field. If a suitable disturbance signal can be measured, an active control system can be used to directly minimise the sc...
Article
Full-text available
Personal Audio refers to the generation of spatially distinct sound zones that allow individuals within a shared space to listen to their own audio material without affecting, or being affected, by others. Recent interest in such systems has focussed on their performance in public spaces where speech privacy is desirable. To achieve this goal, spee...
Conference Paper
The mandatory use of artificial warning sounds by electric vehicles at low speeds has generated concern over the resulting increase in urban noise levels. Systems have been proposed and tested that limit the vehicle’s environmental noise contributions by directing the radiated sound solely towards vulnerable road users. However, such solutions are...
Article
Full-text available
Active structural acoustic control (ASAC) is a widely used active noise control technique that provides control of structurally radiated noise through actuation of the radiating structure. Typically, ASAC drives structural actuators to minimise a real-time measurement of the radiated sound field. However, it is often not practical to position error...
Article
Active control of the sound power scattered by a sphere is theoretically investigated using spherical harmonic expansions of the primary and secondary fields. The sphere has a surface impedance that is uniform, real, and locally reacting while being subjected to an incident monochromatic plane wave. The scattered power is controlled with a number o...
Article
The indoor pass-by noise measurement can nowadays be realised in a laboratory environment with a far field microphone array and a stationary vehicle on a rolling road, according to ISO-362-1:2016. Within this indoor testing procedure, there exists the ability to quantify the contributions from the various noise sources in a car to gain further insi...
Article
Full-text available
Directional sound fields can be generated by arrays of multiple sound sources such as loudspeaker drivers. These systems, though potentially capable of high levels of directivity control over a broad bandwidth, may prove prohibitively expensive, fragile, or impracticable in certain applications. To overcome these limitations, this paper presents an...
Presentation
The use of active control to acoustically cloak an object has been demonstrated previously, and is effective if the scattered component of the pressure field can be measured and directly minimised. In practice, this is non-trivial as a pressure sensor in the sound-field will detect the superposition of the incident and scattered pressures. An alter...
Conference Paper
Full-text available
The use of active control to acoustically cloak an object has been demonstrated previously, and is effective if the scattered component of the pressure field can be measured and directly minimised. In practice, this is non-trivial as a pressure sensor in the sound-field will detect the superposition of the incident and scattered pressures. An alter...
Article
The mandatory use of artificial warning sounds by electric vehicles at low speeds has generated concern over the resulting increase in urban noise levels. Systems have been proposed and tested that limit the vehicle’s environmental noise contributions by directing the radiated sound solely towards vulnerable road users. However, such solutions are...
Article
Full-text available
This paper presents the design and implementation of an active noise control (ANC) headphone system with a directional hear-through capability and compares the performance of this system to that of a standard hear-through headphone system. The directional hear-through ANC headphones are a novel integration of microphone array beamforming and ANC te...
Article
Full-text available
This is a kind invitation to contribute to the special issue on Noise Barriers
Article
No PDF available ABSTRACT Active control of an incident acoustic wave using an array of secondary source has been extensively investigated. In general, the objective is to attenuate the propagating wave so as to generate a space with a reduced sound pressure level. However, there are a variety of applications where more flexible manipulation of the...
Article
No PDF available ABSTRACT Acoustic metamaterials (AMMs) have been demonstrated as an alternative approach to achieving high levels of noise control using an array of subwavelength unit cells, exhibiting behaviour not seen in conventional materials. Specifically, active AMMs offer the potential for greater levels of broadband wave manipulation, tuna...
Article
No PDF available ABSTRACT Undesirable resonant vibrations in a structure can be suppressed using various techniques. However, parametric uncertainty can reduce modelling accuracy and lead to a reduction in the efficacy of the designed suppression system. The suppression of multiple modes of vibration with robustness to parametric uncertainty is ach...
Conference Paper
Full-text available
Active Noise Control (ANC) systems have been employed in a variety of applications to provide high per- formance noise control at low frequencies, within a lightweight and compact package. Recently, acoustic meta- materials (AMM) have been proposed and demonstrated as an alternative approach to achieving high levels of noise control. AMM are engine...
Conference Paper
Full-text available
A theoretical investigation is performed where spherical harmonic series expansions are used to describe the primary and secondary pressure fields in the problem of actively controlling sound scattering around spheres. The study focuses on the scenario of point-monopoles radiators in the vicinity of a sphere with a uniform, locally-reacting and rea...
Conference Paper
Full-text available
There is an interest in many situations to achieve a perfect acoustic cloak, which renders an object acoustically invisible. Although significant contributions have been made to realising passive acoustic cloaks, there is significant potential in the use of active control technologies for cloaking. However, this requires that an accurate estimate o...
Conference Paper
Acoustic black holes are structural features that are realised by tapering the thickness of a beam or plate, usually via a power law profile. Practical acoustic black holes have been shown to significantly reduce vibrations at high frequencies when combined with a thin layer of passive damping but, due to design constraints on the taper length and...
Conference Paper
Full-text available
The indoor pass-by noise measurement can nowadays be realised in a laboratory environment with a microphone array and a stationary vehicle on a rolling road, according to ISO-362-1:2016. Within this indoor testing procedure, the different contributions from the various noise sources on a car can be estimated using an inverse method with a set of mi...
Conference Paper
Full-text available
Active Structural Acoustic Control (ASAC) is a widely used active noise control technique, which provides global control of structurally radiated noise by controlling structural vibrations. Many current ASAC systems rely upon the availability of an accurate, real-time measure of the radiated sound field. This often requires positioning of acoustic...
Conference Paper
Full-text available
Electric vehicles are quiet at low speeds compared to their internal combustion engine counterparts, leading to regulations on the mandatory use of artificial warning sounds for their detection, as a safety measure for other road users. Arguments against the concept have been voiced focusing on the resulting environmental noise pollution, while at...
Conference Paper
Full-text available
The indoor pass-by noise measurement can nowadays be realised in a laboratory environment with a stationary vehicle on a rolling road and a microphone array, according to ISO-362-1:2016. Within this indoor testing procedure, there is also the option of evaluating the different contributions from the various noise sources on a car, for example using...
Article
Acoustic black holes (ABHs) are geometric structural features that provide a potential lightweight damping solution for flexural vibrations. In this article, a parametric study of an ABH on a beam has been carried out to assess how practical design constraints affect its behaviour, thus providing detailed insight into design trade-offs. The reflect...
Article
Full-text available
The radiation resistance matrix allows for the calculation of structurally radiated sound power using a series of measured structural responses. Currently, estimating the radiation resistance matrix requires precise modelling of the structure which, for practical structures, can lead to estimation errors. This paper presents two methods for identif...
Article
Active noise cancelling (ANC) headphones have seen significant commercial success and a number of control strategies have been proposed, including feedforward, feedback and hybrid configurations, using both analogue and digital implementations. Irrespective of the configuration or implementation approach, the strategies proposed in the open-literat...
Conference Paper
Full-text available
It is often difficult to position microphones at the ear position of listeners to directly monitor the perceived sound, in local active sound control systems for example. The pressure at these positions can be estimated using virtual sensing with an array of remote monitoring microphones, however, if some assumptions are made about the sound field....
Article
Full-text available
Excessive noise in hospitals adversely affects patients’ sleep and recovery, causes stress and fatigue in staff and hampers communication. The World Health Organization suggests sound levels should be limited to 35 decibels. This is probably unachievable in intensive care units, but some reduction from current levels should be possible. A prelimina...
Conference Paper
Full-text available
Directional sound fields can be generated by arrays of multiple sound sources, with the most common and straightforward method being an array of loudspeaker drivers. Although such a system, when appropriately designed, is capable of high levels of directivity control over a broad bandwidth and with good audio quality, it can be prohibitively expens...
Article
Full-text available
The reflection coefficient for a one-dimensional elastic wedge driven from an adjacent uniform plate is analysed using higher-order WKB-method matrix analysis and the results are compared with numerical simulations using Finite Elements. The numerical results are correctly predicted by the WKB analysis above a certain frequency. In general, this fr...
Technical Report
Full-text available
Active control systems are used in many applications to reduce a disturbance signal with the addition of control sources. Commonly, these systems are run on dedicated Digital Signal Processing (DSP) hardware, designed to run such tasks efficiently and with minimal system latency. Whilst these dedicated platforms are effective, they can be costly an...
Technical Report
Full-text available
Active control systems are used in many applications to re- duce a disturbance signal with the addition of control sources. Commonly, these systems are run on dedicated Digital Sig- nal Processing (DSP) hardware, designed to run such tasks efficiently and with minimal system latency. Whilst these dedicated platforms are effective, they can be costl...
Conference Paper
Full-text available
Personal Audio systems can be used to provide information and entertainment content in public spaces. Limitations in array directivity mean that speech information intended for a target region may remain intelligible elsewhere. This compromises privacy for target listeners and could prove distracting or annoying to passive listeners nearby. A syste...