Michael J. Griffin

Michael J. Griffin
University of Southampton · Institute of Sound and Vibration Research (ISVR)

About

463
Publications
63,683
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
17,533
Citations
Citations since 2016
29 Research Items
6817 Citations
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000

Publications

Publications (463)
Article
p>Seat effective amplitude transmissibilities (SEAT values) quantify the influence of seats on discomfort caused by vibration. This study investigated SEAT values with vertical mechanical shocks at low, medium, and high magnitudes (0.5, 1.0, and 2.0 ms<sup>−1.75</sup>) at frequencies between 1.0 and 16 Hz. With 18 subjects sitting on a rigid seat a...
Article
This study examined how the apparent mass and transmissibility of the human body depend on the magnitude of fore-and-aft vibration excitation and the presence of vertical vibration. Fore-and-aft and vertical acceleration at five locations along the spine, and pitch acceleration at the pelvis, were measured in 12 seated male subjects during fore-and...
Article
Postural stability can be threatened by the low-frequency motions in transport that are usually quantified by their root-mean-square (r.m.s.) acceleration. This study investigated how the stability of walking people depends on the waveform of 1- and 2-Hz mediolateral oscillations of the surface on which they walk. Walking on a treadmill, 20 subject...
Article
Full-text available
Standards assume vibration discomfort depends on the frequency and direction of whole-body vibration, with the same weightings for frequency and direction at all magnitudes. This study determined equivalent comfort contours from 1.0 to 10 Hz in each of three directions (fore-and-aft, lateral, vertical) at magnitudes in the range 0.1 to 3.5 ms⁻² r.m...
Conference Paper
Full-text available
The perception of fine textures is believed to depend on the encoding of high frequency vibration by the Pacinian (PC) channel. However, the rapidly-adapting (RA) channel may also be able to encode the frequency of vibration. The aim of this study was to investigate whether the ability to perceive changes in the frequency of 100-Hz vibration at the...
Article
When measuring total dynamic forces between the human body and seats during vibration, variations in force over the buttocks and the thighs have previously been ignored. In this study, sensors in a pressure mat were calibrated by applying static and dynamic pressures through foam and calculating transfer functions between the applied pressures and...
Article
This study investigated effects of applied force on the apparent mass of the hand, the dynamic stiffness of glove materials, and the transmission of vibration to the hand. For 10 subjects, three glove materials, and three contact forces, apparent masses and glove transmissibilities were measured at the palm and at a finger at frequencies in the ran...
Article
The frequency content of a mechanical shock is not confined to its fundamental frequency, so it was hypothesized that the frequency-dependence of discomfort caused by shocks with defined fundamental frequencies will differ from the frequency-dependence of sinusoidal vibration. Subjects experienced vertical vibration and vertical shocks with fundame...
Article
Full-text available
Background: Thermotactile thresholds and vibrotactile thresholds are measured to assist the diagnosis of the sensorineural component of the hand-arm vibration syndrome (HAVS). Objectives: This study investigates whether thermotactile and vibrotactile thresholds distinguish between fingers with and without numbness and tingling. Methods: In 60...
Conference Paper
Full-text available
A full understanding of the relationship between the physics of vibration and the perception of vibration, vibrotactile psychophysics, would be a powerful tool. However, vibration perception is complex: vibrations are perceived more easily at some frequencies than at others and the perception of vibration varies with contactor size, body location,...
Conference Paper
Full-text available
The practical application of currently standardised methods of evaluating wholebody vibration assumes the discomfort caused by a combination of frequency components can be predicted using time averaging methods, such as the rootmean-square, r.m.s., or vibration dose value, VDV. This study investigated whether the discomfort produced by random vibra...
Article
Full-text available
Purpose: This study investigates the effects of room temperature on two standard tests used to assist the diagnosis of vibration-induced white finger (VWF): finger rewarming times and finger systolic blood pressures. Methods: Twelve healthy males and twelve healthy females participated in four sessions to obtain either finger skin temperatures (...
Article
Biodynamic responses of the seated human body are usually measured and modelled assuming a single point of vibration excitation. With vertical vibration excitation, this study investigated how forces are distributed over the body-seat interface. Vertical and fore-and-aft forces were measured beneath the ischial tuberosities, middle thighs, and fron...
Article
Full-text available
In this paper, we prove the existence of an infinite-dimensional graded supermodule for the finite sporadic Thompson group Th whose McKay–Thompson series are weakly holomorphic modular forms of weight 12\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{...
Article
Full-text available
The transmission of vibration through a passenger train seat to the seat pan and to the backrest has been measured in the fore-and-aft, lateral and vertical directions with 12 subjects using 0.5–40 Hz random vibration (with both single-axis and tri-axial excitation) and using simulated tri-axial train vibration. There were small differences in tran...
Article
Full-text available
Background and objective The American Academy of Pediatrics recommends that preterm infants complete a predischarge ‘car seat challenge’ observation for cardiorespiratory compromise while in a car seat. This static challenge does not consider the more upright position in a car or the vibration of the seat when the car is moving. This pilot study wa...
Conference Paper
Full-text available
Thresholds for the perception of vibration at the hand are measured for diagnostic and research purposes but thresholds are limited in what they indicate about tactile perception. This review discusses the conceptual and methodological limitations in using thresholds to understand the information processing systems which underlie the perception of...
Conference Paper
Full-text available
British and International standards provide frequency weightings to assist the prediction of the discomfort caused by fore-and-aft, lateral and vertical wholebody vibration. The practical application of the weightings assumes that the frequency-dependence and directional-dependence of vibration discomfort is independent of the magnitude of vibratio...
Article
Full-text available
p>Background: Vibration-induced white finger (VWF) is the vascular component of the hand–arm vibration syndrome (HAVS). Two tests have been standardised so as to assist the diagnosis of VWF: the measurement of finger rewarming times and the measurement of finger systolic blood pressures (FSBPs). Objectives: This study investigates whether the two...
Article
Full-text available
Aims/hypothesis: The effect of n-3 fatty acid treatment on temperature perception as a sensory nerve function modality is uncertain. In patients with non-alcoholic fatty liver disease (NAFLD) both with and without type 2 diabetes, we: (1) tested whether 15-18 months' treatment with 4 g/day of docosahexaenoic plus eicosapentaenoic acid (DHA+EPA) im...
Article
The biodynamic response of the seated human body has been investigated with 20 males exposed to upward and downward shocks at 13 fundamental frequencies (1–16 Hz) and 18 magnitudes (up to ±8.3 ms⁻²). For 1- and 2- degree-of-freedom models, the stiffness and damping coefficients were obtained by fitting seat acceleration waveforms predicted from the...
Article
For three samples of material (12.5, 25.0 and 37.5 mm diameter) from each of three gloves, the dynamic stiffnesses and the vibration transmissibilities of the materials (to both the palm of the hand and the thenar eminence) were measured at frequencies from 10 to 300 Hz. Additional measurements showed the apparent masses of the hand at the palm and...
Article
The frequency dependence of discomfort caused by vertical mechanical shocks has been investigated with 20 seated males exposed to upward and downward shocks at 13 fundamental frequencies (1–16 Hz) and 18 magnitudes (±0.12 to ±8.3 ms−2). The rate of growth of discomfort with increasing shock magnitude depended on the fundamental frequency of the sho...
Article
Purpose: This study investigated whether the reductions in finger blood flow induced by 125-Hz vibration applied to different locations on the hand depend on thresholds for perceiving vibration at these locations. Methods: Subjects attended three sessions during which vibration was applied to the right index finger, the right thenar eminence, or th...
Article
Full-text available
The two Rogers-Ramanujan q-series \sum_{n=0}^{\infty}\frac{q^{n(n+\sigma)}}{(1-q)\cdots (1-q^n)}, where \sigma=0,1, play many roles in mathematics and physics. By the Rogers-Ramanujan identities, they are essentially modular functions. Their quotient, the Rogers-Ramanujan continued fraction, has the special property that its singular values are alg...
Article
Full-text available
The Umbral Moonshine Conjectures assert that there are infinite-dimensional graded modules, for prescribed finite groups, whose McKay-Thompson series are certain distinguished mock modular forms. Gannon has proved this for the special case involving the largest sporadic simple Mathieu group. Here we establish the existence of the umbral moonshine m...
Article
It might be assumed that increasing the thickness of a glove would reduce the vibration transmitted to the hand. Three material samples from an anti-vibration glove were stacked to produce three thicknesses: 6.4, 12.8 and 19.2 mm. The dynamic stiffnesses of all three thicknesses, the apparent mass at the palm and the finger and the transmission of...
Article
Full-text available
Floor vibrations induced by humans walking barefoot were investigated in heavyweight buildings. Six floating floors with different floor structures and thick resilient isolators were built in laboratories with the same dimensions and boundary conditions. Subjective tests were performed to assess the vibration serviceability of the floor structures....
Article
The detection of a vibration may be reduced by the presence of another vibration: a phenomenon known as 'masking'. This study investigated how the detection of one frequency of vibration is influenced by vibration at another frequency. With nine subjects, thresholds for detecting fore-and-aft backrest vibration were determined (for 4, 8, 16, and 31...
Article
Full-text available
Measurements of the transmission of vibration from the floor beneath a seat to interfaces between the seat and the human body are used to characterise the dynamic performance of the seat. Most studies of seat transmissibility concern the transmission of vertical vibration through seat pan cushions, but fore-and-aft vibration at a seat pan and backr...
Article
The effect of n-3 fatty acid treatment on vibration perception thresholds (VPTs) and cutaneous microvascular reactivity is not known. We tested whether: (1) a 15-18 month treatment with high dose (4 g/day) docosahexaenoic (DHA) plus eicosapentaenoic (EPA) acid improved VPT and microvascular reactivity in patients with non-alcoholic fatty liver dise...
Article
Few studies have investigated discomfort caused by multi-axis vibration and none has explored methods of predicting the discomfort of standing people from simultaneous fore-and-aft, lateral and vertical vibration of a floor. Using the method of magnitude estimation, 16 subjects estimated their discomfort caused by dual-axis and tri-axial motions (o...
Article
This study investigated whether the method for eliciting vibration-induced oVEMPs could be improved by applying vibration directly to the teeth, and how vibration-induced oVEMP responses depend on the duration of the applied vibration. In 10 participants, a hand-held shaker was used to present 100-Hz vibration tone pips to the teeth via a customise...
Article
Unlabelled: Biodynamic models representing distributed human-seat interactions can assist seat design. This study sought to develop a finite element (FE) model representing the soft tissues of the body supported by seating and the vertical in-line apparent mass and the fore-and-aft cross-axis apparent mass of the seated human body during vertical...
Article
Full-text available
Unlabelled: The transmissibility of seat depends on the dynamics of both the seat and the human body, and shows how the amplification and attenuation of vibration varies with the frequency of vibration. A systematic methodology was developed for finite element (FE) modelling of the dynamic interaction between a seat and the human body and predicti...
Article
This study investigated the effect of hand elevation on reductions in finger blood flow (FBF) induced by hand-transmitted vibration. Fourteen males attended six sessions on six separate days, with a control sessions and a vibration session (125-Hz vibration at 44 ms(-2) rms) with the right hand supported at each of three elevations: 20 cm below hea...
Article
Full-text available
Monstrous moonshine relates distinguished modular functions to the representation theory of the Monster . The celebrated observations that $$ 1=1,\ \ \ 196884=1+196883,\ \ \ 21493760=1+196883+21296876,\ \ \ \dots\dots (*)$$ illustrate the case of J(τ)=j(τ)−744, whose coefficients turn out to be sums of the dimensions of the 194 irreducible represen...
Article
While walking on a treadmill, 20 subjects experienced lateral oscillations: frequencies from 0.5 to 2Hz and velocities from 0.05 to 0.16ms21 rms. Postural stability was indicated by ratings of ‘discomfort or difficulty in walking’, the movement of the centre of pressure beneath the feet and lateral forces applied to a hand support. Hand support imp...
Article
Unlabelled: Passengers and crew on fast boats can experience high magnitudes of whole-body vibration and mechanical shocks that may present risks to health and cause discomfort. This study investigated the influence of reclining a seat on the discomfort caused by fast-boat motion and whether discomfort can be predicted by overall ride values accor...
Article
This study investigated the prediction of the discomfort caused by simultaneous noise and vibration from the discomfort caused by noise and the discomfort caused by vibration when they are presented separately. A total of 24 subjects used absolute magnitude estimation to report their discomfort caused by seven levels of noise (70-88 dBA SEL), 7 mag...
Article
Unlabelled: At work or in leisure activities, many people are exposed to vibration or mechanical shocks associated with risks of injury or disease. This paper identifies information that can be used to decide whether there may be a risk from exposure to hand-transmitted vibration or whole-body vibration and shock, and suggests actions that can con...
Article
The discomfort caused by lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation has been investigated at frequencies between 0.25 and 1.0 Hz when sitting on a rigid seat and when sitting on a compliant cushion, both without a backrest. Judgements of vibration discomfort and the transmission of lateral and roll oscilla...
Article
Objectives To assess the relation between Dupuytren’s contracture and occupational exposure to hand-transmitted vibration (HTV). Method We mailed a questionnaire to 21 201 subjects of working age, chosen randomly from the age-sex registers of 34 general practices in Great Britain and to 993 subjects randomly selected from military pay records. We a...
Article
In International Standard 10819 (1996), the requirements for a glove to be considered an 'anti-vibration glove' are determined by the transmission of vibration to the palm of the hand. The transmission of vibration to a finger is very different from the transmission of vibration to the palm, but there are currently no requirements to measure the tr...
Article
How noise discomfort and vibration discomfort depend on duration has not previously been compared. For five durations (2, 4, 8, 16 and 32 s), the subjective equivalence of noise and vibration was investigated with all 49 combinations of 7 levels of noise and 7 magnitudes of whole-body vertical vibration. The rates of increase in discomfort with inc...
Article
The extent to which a seat can provide useful attenuation of vehicle vibration depends on three factors: the characteristics of the vehicle motion, the vibration transmissibility of the seat, and the sensitivity of the body to vibration. The 'seat effective amplitude transmissibility' (i.e., SEAT value) reflects how these three factors vary with th...
Article
This study investigated how the vasoconstriction induced by vibration depends on the frequency of vibration when the vibration magnitude is defined by individual thresholds for perceiving vibration [i.e. sensation levels (SL)]. Fourteen healthy subjects attended the laboratory on seven occasions: for six vibration frequencies (8, 16, 31.5, 63, 125,...
Article
The dependence of biodynamic responses of the seated human body on the frequency, magnitude and waveform of vertical vibration has been studied in 20 males and 20 females. With sinusoidal vibration (13 frequencies from 1 to 16 Hz) at five magnitudes (0.1-1.6 ms(- 2) r.m.s.) and with random vibration (1-16 Hz) at the same magnitudes, the apparent ma...
Article
Frequency weightings for predicting vibration discomfort assume the same frequency-dependence at all magnitudes of vibration, whereas biodynamic studies show that the frequency-dependence of the human body depends on the magnitude of vibration. This study investigated how the frequency-dependence of vibration discomfort depends on the acceleration...
Article
Full-text available
the AAP recommends preterm infants undergo a “car seat challenge” before discharge, to observe for any differences in cardiorespiratory function whilst seated in a car seat compared to lying flat in a cot. The infant can be discharged if there is no compromise. This static (30°) challenge does not take into account the more vertical positioning of...
Article
The method of magnitude estimation is used in psychophysical studies to obtain numerical values for the intensity of perception of environmental stresses (e.g., noise and vibration). The exponent in a power function relating the subjective magnitude of a stimulus (e.g., the degree of discomfort) to the physical magnitude of the stimulus shows the r...
Article
Full-text available
The relation between Dupuytren's contracture and occupational exposure to hand-transmitted vibration (HTV) has frequently been debated. We explored associations in a representative national sample of workers with well-characterised exposure to HTV. We mailed a questionnaire to 21 201 subjects aged 16-64 years, selected at random from the age-sex re...
Conference Paper
p>The discomfort caused by combined noise and vibration may be different from the sum of the discomfort caused by noise and the discomfort caused by vibration when they are presented separately. This experimental study investigated how judgements of discomfort caused by simultaneous noise and vibration depend on the level of noise and the magnitude...
Conference Paper
Full-text available
Floor vibrations induced by human walking were investigated in a reinforced concrete structure. Six experimental floor structures were built in laboratories with the same dimensions and boundary conditions. Subjective tests were performed to assess the vibration serviceability of the floor structures. First, the subjects were asked to walk across a...
Conference Paper
Full-text available
It should be possible to predict the transmission of vibration through a glove from an understanding of the dynamic stiffness of the glove material and the mechanical impedance of the hand. The objective of this study was to investigate whether mechanical impedance methods could predict differences between the transmissibility of glove material to...
Article
While walking on an instrumented treadmill, 20 subjects were perturbed by lateral sinusoidal oscillations representative of those encountered in transport: frequencies in the range 0.5-2 Hz and accelerations in the range 0.1-2.0 ms(-2) r.m.s., corresponding to velocities in the range 0.032-0.16 ms(-1) r.m.s. Postural stability was assessed from the...
Article
Full-text available
The effects of noise and vibration on annoyance in buildings during the passage of a nearby high-speed train have been investigated in a laboratory experiment with recorded train noise and 20 Hz vibration. The noises included the effects of two types of façade: windows-open and windows-closed. Subjects were exposed to six levels of noise and six ma...
Article
Thresholds for the perception of vibration on the hand reduce with increasing area of excitation when the thresholds are mediated by the Pacinian channel (a phenomenon known as spatial summation) but thresholds are generally independent of the area of excitation when they are mediated by non-Pacinian channels. The effect of the area of excitation o...
Article
Lateral acceleration causes discomfort but how the discomfort depends on the frequency of acceleration or characteristics of seating is poorly understood. Using magnitude estimation, twelve male subjects rated the discomfort caused by lateral oscillation at eight frequencies (0.2-1.0 Hz) across four seating conditions (a rigid seat and a train seat...
Article
The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the dynamic characteristics of the seat, and the dynamic characteristics of the person sitting on the seat. However, it is not known whether seat cushions influence the dynamic response of the human body, whether the human body influences the dynamic res...
Article
Full-text available
The combination of low-frequency lateral and roll motions experienced in tilting trains can provoke motion sickness. The incidence of sickness depends on vehicle design and subject demographics. Vehicle design affects the location of the centre-of-roll, which influences passenger perception of motion. Age and gender have large influences on suscept...
Article
This study examined how the apparent mass and transmissibility of the human body depend on the magnitude of fore-and-aft vibration excitation and the presence of vertical vibration. Fore-and-aft and vertical acceleration at five locations along the spine, and pitch acceleration at the pelvis, were measured in 12 seated male subjects during fore-and...
Article
Full-text available
Objectives: This study investigated whether reductions in finger blood flow (FBF) during and after vibration are similarly dependent on the magnitude and duration of the vibration. Methods: FBF on the left and right hand was measured every minute during, and for 1 h following, exposure of the right hand to one of three magnitudes of 125-Hz sinus...
Article
Current methods for evaluating seat vibration to predict vibration discomfort assume the same frequency weightings and axis multiplying factors can be used at the seat surface and the backrest irrespective of the backrest inclination. This experimental study investigated the discomfort arising from whole-body vertical vibration when sitting on a ri...
Article
Unlabelled: Roll compensation during cornering (aligning the feet-to-head axis of the body with the resultant force) reduces lateral acceleration, but how any improvement in comfort depends on the frequency of the acceleration has not previously been investigated. Seated subjects judged the discomfort caused by lateral oscillation, roll oscillatio...
Article
Full-text available
This invited paper reviews experimental studies of the frequency-dependence of absolute thresholds for the perception of vibration, equivalent comfort contours, temporary changes in sensation caused by vibration, and reductions in finger blood flow caused by hand-transmitted vibration. Absolute thresholds depend on the contact conditions but for a...
Article
This study investigated whether the reductions in finger blood flow induced by 125-Hz vibration applied to different locations on the hand depend on thresholds for perceiving vibration at these locations. Subjects attended three sessions during which vibration was applied to the right index finger, the right thenar eminence, or the left thenar emin...
Conference Paper
Full-text available
This study investigated the effects of noise and vibration on annoyance in buildings in a laboratory experiment with recorded train noise and 20 Hz vertical vibration. The noises included the effects of two types of facade: windows-open and windows-closed. The experiment consisted of four sessions: 1) evaluation of noise annoyance in the absence of...
Article
Full-text available
In this paper we report the results of an experiment to investigate the emergence of ocular vestibular evoked myogenic potentials (OVEMPs) during the linear vestibular ocular reflex (LVOR) evoked by whole body vibration (WBV). OVEMP and electro-oculogram (EOG) montages were employed to record peri-ocular potentials (POPs) from six subjects during W...
Article
The relative discomfort caused by noise and vibration, how this depends on the level of noise and the magnitude of vibration, and whether the noise and vibration are presented simultaneously or sequentially has been investigated in a laboratory study with 20 subjects. Noise and vertical vibration were reproduced with all 49 combinations of 7 levels...
Article
Unlabelled: This study determined how backrest inclination and the frequency and magnitude of vertical seat vibration influence vibration discomfort. Subjects experienced vertical seat vibration at frequencies in the range 2.5-25 Hz at vibration magnitudes in the range 0.016-2.0 ms(-2) r.m.s. Equivalent comfort contours were determined with five b...