John Davy | RMIT University (original) (raw)

Papers by John Davy

Research paper thumbnail of Is driving experience all that matters? Drivers’ takeover performance in conditionally automated driving

Journal of Safety Research, Aug 1, 2023

Research paper thumbnail of Influence of non-driving related tasks on driving performance after takeover transition in conditionally automated driving

Transportation Research Part F-traffic Psychology and Behaviour, Jul 1, 2023

Research paper thumbnail of Optimization of the Acoustic Performance of a Composite Multi-cell Sound Absorber

Acoustics Australia, May 17, 2023

Research paper thumbnail of Enhancement of the sound absorption coefficient experimental reproducibility for different size samples

Applied Acoustics, Nov 1, 2022

Research paper thumbnail of Prediction of the sound absorption of micro-perforated panels whose holes are extended in length by tubes

Research paper thumbnail of Empirical corrections for predicting the sound insulation of double leaf cavity stud building elements with stiffer studs

Journal of the Acoustical Society of America, Feb 1, 2019

Research paper thumbnail of Prediction of the acoustic effect of an interior trim porous material inside a rigid-walled car air cavity model

Applied Acoustics, Aug 1, 2020

Research paper thumbnail of The Concept modeling method: An approach to optimize the structural dynamics of a vehicle body

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, Jun 18, 2020

Research paper thumbnail of Data augmentation on convolutional neural networks to classify mechanical noise

Applied Acoustics, Feb 1, 2023

Research paper thumbnail of Advanced seating comfort: suppression of vibration using multi-mode piezoelectric shunt damping

International Journal of Vehicle Noise and Vibration

Research paper thumbnail of The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

Journal of Vibration and Control, 2021

Industry is moving towards more data-oriented design and analyses to solve complex analytical pro... more Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predi...

Research paper thumbnail of The geometric mean is a superior frequency response averaging method for human body vibration

Ergonomics, 2020

The frequency response data of human body vibration are often used for standardisation, design of... more The frequency response data of human body vibration are often used for standardisation, design of transport vehicles and occupational health and safety measures. This article shows that the commonly used methods of averaging frequency response spectra, such as arithmetic averaging in the complex or magnitude domain and median averaging, are not as suitable as the less commonly used geometric averaging in the complex domain. This is because it is necessary to minimise the deviation of the measured values about the mean value and to minimise the bias from the true mean value due to noise, distortion and nonlinearity. Practitioner summary: For averaging frequency response spectra, it is necessary to minimise the bias from the true mean value. This research shows that the commonly used averaging methods, such as arithmetic averaging in the complex or magnitude domain and the median, are not as suitable as geometric averaging in the complex domain. Abbreviations: H1 Estimator: frequency ...

Research paper thumbnail of Effects of Vibration on Seated Human Drowsiness/Alertness

Vibration Engineering for a Sustainable Future, 2021

Drowsiness is one of the major hazards contributing to transportation accidents. This project aim... more Drowsiness is one of the major hazards contributing to transportation accidents. This project aims to investigate the effects of the low-frequency vibration on vehicle driver drowsiness. Heart rate variability (HRV) and the subjective sleepiness scale are used to measure the alertness/drowsiness level. A random vibration signal with a limited band frequency (4–7 Hz) is used to expose volunteers to whole-body vibration. Ten young and healthy volunteers have participated in this project. The results show that vibration can have a significant effect on the induction of drowsiness.

Research paper thumbnail of Mel frequency cepstral coefficient temporal feature integration for classifying squeak and rattle noise

The Journal of the Acoustical Society of America, 2021

Fault identification using the emitted mechanical noise is becoming an attractive field of resear... more Fault identification using the emitted mechanical noise is becoming an attractive field of research in a variety of industries. It is essential to rank acoustic feature integration functions on their efficiency to classify different types of sound for conducting a fault diagnosis. The Mel frequency cepstral coefficient (MFCC) method was used to obtain various acoustic feature sets in the current study. MFCCs represent the audio signal power spectrum and capture the timbral information of sounds. The objective of this study is to introduce a method for the selection of statistical indicators to integrate the MFCC feature sets. Two purpose-built audio datasets for squeak and rattle were created for the study. Data were collected experimentally to investigate the feature sets of 256 recordings from 8 different rattle classes and 144 recordings from 12 different squeak classes. The support vector machine method was used to evaluate the classifier accuracy with individual feature sets. T...

Research paper thumbnail of The sound insulation and directivity of the sound radiation from double glazed windows

The Journal of the Acoustical Society of America, 2020

The sound insulation and directivity of the radiated sound from double glazed windows have been m... more The sound insulation and directivity of the radiated sound from double glazed windows have been measured by different researchers. Previously, airborne sound insulation models have been used to predict the associated measurement results with limited success. In this paper, the importance of accounting for the structure borne sound transmission between two glazing elements via the window frame on the prediction results is demonstrated. The decreased stiffness of the wall cavity as the depth is increased is the reason why sound transmission via the window frame needs to be considered. The reciprocity argument provided by Davy for the prediction of the directivity of sound radiating into a room is validated and it is shown that once the structure borne transmission is considered, an additional weighting term is not needed to compensate for the extra wall collisions which the sound experiences when radiated at grazing incidence.

Research paper thumbnail of Squeak and rattle noise classification using radial basis function neural networks

Noise Control Engineering Journal, 2020

In this article, an artificial neural network is proposed to classify short audio sequences of sq... more In this article, an artificial neural network is proposed to classify short audio sequences of squeak and rattle (S&R) noises. The aim of the classification is to see how accurately the trained classifier can recognize different types of S&R sounds. Having a high accuracy model that can recognize audible S&R noises could help to build an automatic tool able to identify unpleasant vehicle interior sounds in a matter of seconds from a short audio recording of the sounds. In this article, the training method of the classifier is proposed, and the results show that the trained model can identify various classes of S&R noises: simple (binary clas- sification) and complex ones (multi class classification).

Research paper thumbnail of Two definitions of the inner product of modes and their use in calculating non-diffuse reverberant sound fields

The Journal of the Acoustical Society of America, 2019

There are two definitions of the inner product of modal spatial functions used in the literature.... more There are two definitions of the inner product of modal spatial functions used in the literature. Both definitions integrate the product of the modal spatial functions over a line, area, or volume. The only difference is that one of the definitions takes the complex conjugate of one of the modal spatial functions before multiplying the modes together. The definitions are the same if the modal spatial functions are real. If the modal spatial functions are complex, only the definition which takes the complex conjugate is an inner product. If the specific acoustic impedance of the boundaries has a real part, then the modes are only orthogonal with the definition which does not take the complex conjugate, although this definition is not strictly an inner product because the modal spatial functions are complex in this situation. However, this definition of “inner product” can be used to calculate the coefficients in the modal expansion of the system response. On the other hand, when it c...

Research paper thumbnail of Estimating the diffuseness of sound fields: A wavenumber analysis method

The Journal of the Acoustical Society of America, 2017

The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The d... more The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The diffuse sound field is generally described as composed of plane waves with random phases, which wave number vectors are uniformly distributed over all angles of incidence. In this study, an interpretation in the spatial frequency domain is discussed, with the prospect of evaluating the diffuse field conditions in non-anechoic enclosures. This work examines how theoretical considerations compare with experimental results obtained in rooms with various diffuse field conditions. In addition, the paper investigates how the results relate to the modal theory of room acoustics, based on the conception that any mode, also in non-rectangular rooms, can be expanded into a number of propagating waves.

Research paper thumbnail of Sound transmission loss of ETICS cladding systems considering the structure-borne transmission via the mechanical fixings: Numerical prediction model and experimental evaluation

Research paper thumbnail of Predicting the absorption of perforated panels backed by resistive textiles

Noise Control Engineering Journal, 2016

Research paper thumbnail of Is driving experience all that matters? Drivers’ takeover performance in conditionally automated driving

Journal of Safety Research, Aug 1, 2023

Research paper thumbnail of Influence of non-driving related tasks on driving performance after takeover transition in conditionally automated driving

Transportation Research Part F-traffic Psychology and Behaviour, Jul 1, 2023

Research paper thumbnail of Optimization of the Acoustic Performance of a Composite Multi-cell Sound Absorber

Acoustics Australia, May 17, 2023

Research paper thumbnail of Enhancement of the sound absorption coefficient experimental reproducibility for different size samples

Applied Acoustics, Nov 1, 2022

Research paper thumbnail of Prediction of the sound absorption of micro-perforated panels whose holes are extended in length by tubes

Research paper thumbnail of Empirical corrections for predicting the sound insulation of double leaf cavity stud building elements with stiffer studs

Journal of the Acoustical Society of America, Feb 1, 2019

Research paper thumbnail of Prediction of the acoustic effect of an interior trim porous material inside a rigid-walled car air cavity model

Applied Acoustics, Aug 1, 2020

Research paper thumbnail of The Concept modeling method: An approach to optimize the structural dynamics of a vehicle body

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, Jun 18, 2020

Research paper thumbnail of Data augmentation on convolutional neural networks to classify mechanical noise

Applied Acoustics, Feb 1, 2023

Research paper thumbnail of Advanced seating comfort: suppression of vibration using multi-mode piezoelectric shunt damping

International Journal of Vehicle Noise and Vibration

Research paper thumbnail of The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

Journal of Vibration and Control, 2021

Industry is moving towards more data-oriented design and analyses to solve complex analytical pro... more Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predi...

Research paper thumbnail of The geometric mean is a superior frequency response averaging method for human body vibration

Ergonomics, 2020

The frequency response data of human body vibration are often used for standardisation, design of... more The frequency response data of human body vibration are often used for standardisation, design of transport vehicles and occupational health and safety measures. This article shows that the commonly used methods of averaging frequency response spectra, such as arithmetic averaging in the complex or magnitude domain and median averaging, are not as suitable as the less commonly used geometric averaging in the complex domain. This is because it is necessary to minimise the deviation of the measured values about the mean value and to minimise the bias from the true mean value due to noise, distortion and nonlinearity. Practitioner summary: For averaging frequency response spectra, it is necessary to minimise the bias from the true mean value. This research shows that the commonly used averaging methods, such as arithmetic averaging in the complex or magnitude domain and the median, are not as suitable as geometric averaging in the complex domain. Abbreviations: H1 Estimator: frequency ...

Research paper thumbnail of Effects of Vibration on Seated Human Drowsiness/Alertness

Vibration Engineering for a Sustainable Future, 2021

Drowsiness is one of the major hazards contributing to transportation accidents. This project aim... more Drowsiness is one of the major hazards contributing to transportation accidents. This project aims to investigate the effects of the low-frequency vibration on vehicle driver drowsiness. Heart rate variability (HRV) and the subjective sleepiness scale are used to measure the alertness/drowsiness level. A random vibration signal with a limited band frequency (4–7 Hz) is used to expose volunteers to whole-body vibration. Ten young and healthy volunteers have participated in this project. The results show that vibration can have a significant effect on the induction of drowsiness.

Research paper thumbnail of Mel frequency cepstral coefficient temporal feature integration for classifying squeak and rattle noise

The Journal of the Acoustical Society of America, 2021

Fault identification using the emitted mechanical noise is becoming an attractive field of resear... more Fault identification using the emitted mechanical noise is becoming an attractive field of research in a variety of industries. It is essential to rank acoustic feature integration functions on their efficiency to classify different types of sound for conducting a fault diagnosis. The Mel frequency cepstral coefficient (MFCC) method was used to obtain various acoustic feature sets in the current study. MFCCs represent the audio signal power spectrum and capture the timbral information of sounds. The objective of this study is to introduce a method for the selection of statistical indicators to integrate the MFCC feature sets. Two purpose-built audio datasets for squeak and rattle were created for the study. Data were collected experimentally to investigate the feature sets of 256 recordings from 8 different rattle classes and 144 recordings from 12 different squeak classes. The support vector machine method was used to evaluate the classifier accuracy with individual feature sets. T...

Research paper thumbnail of The sound insulation and directivity of the sound radiation from double glazed windows

The Journal of the Acoustical Society of America, 2020

The sound insulation and directivity of the radiated sound from double glazed windows have been m... more The sound insulation and directivity of the radiated sound from double glazed windows have been measured by different researchers. Previously, airborne sound insulation models have been used to predict the associated measurement results with limited success. In this paper, the importance of accounting for the structure borne sound transmission between two glazing elements via the window frame on the prediction results is demonstrated. The decreased stiffness of the wall cavity as the depth is increased is the reason why sound transmission via the window frame needs to be considered. The reciprocity argument provided by Davy for the prediction of the directivity of sound radiating into a room is validated and it is shown that once the structure borne transmission is considered, an additional weighting term is not needed to compensate for the extra wall collisions which the sound experiences when radiated at grazing incidence.

Research paper thumbnail of Squeak and rattle noise classification using radial basis function neural networks

Noise Control Engineering Journal, 2020

In this article, an artificial neural network is proposed to classify short audio sequences of sq... more In this article, an artificial neural network is proposed to classify short audio sequences of squeak and rattle (S&R) noises. The aim of the classification is to see how accurately the trained classifier can recognize different types of S&R sounds. Having a high accuracy model that can recognize audible S&R noises could help to build an automatic tool able to identify unpleasant vehicle interior sounds in a matter of seconds from a short audio recording of the sounds. In this article, the training method of the classifier is proposed, and the results show that the trained model can identify various classes of S&R noises: simple (binary clas- sification) and complex ones (multi class classification).

Research paper thumbnail of Two definitions of the inner product of modes and their use in calculating non-diffuse reverberant sound fields

The Journal of the Acoustical Society of America, 2019

There are two definitions of the inner product of modal spatial functions used in the literature.... more There are two definitions of the inner product of modal spatial functions used in the literature. Both definitions integrate the product of the modal spatial functions over a line, area, or volume. The only difference is that one of the definitions takes the complex conjugate of one of the modal spatial functions before multiplying the modes together. The definitions are the same if the modal spatial functions are real. If the modal spatial functions are complex, only the definition which takes the complex conjugate is an inner product. If the specific acoustic impedance of the boundaries has a real part, then the modes are only orthogonal with the definition which does not take the complex conjugate, although this definition is not strictly an inner product because the modal spatial functions are complex in this situation. However, this definition of “inner product” can be used to calculate the coefficients in the modal expansion of the system response. On the other hand, when it c...

Research paper thumbnail of Estimating the diffuseness of sound fields: A wavenumber analysis method

The Journal of the Acoustical Society of America, 2017

The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The d... more The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The diffuse sound field is generally described as composed of plane waves with random phases, which wave number vectors are uniformly distributed over all angles of incidence. In this study, an interpretation in the spatial frequency domain is discussed, with the prospect of evaluating the diffuse field conditions in non-anechoic enclosures. This work examines how theoretical considerations compare with experimental results obtained in rooms with various diffuse field conditions. In addition, the paper investigates how the results relate to the modal theory of room acoustics, based on the conception that any mode, also in non-rectangular rooms, can be expanded into a number of propagating waves.

Research paper thumbnail of Sound transmission loss of ETICS cladding systems considering the structure-borne transmission via the mechanical fixings: Numerical prediction model and experimental evaluation

Research paper thumbnail of Predicting the absorption of perforated panels backed by resistive textiles

Noise Control Engineering Journal, 2016