Armada Model Designs Ltd is currently seeking funding and/or collaboration to investigate the potential aeroacoustic effects of the local aerodynamic flowfield on a pedal cyclist's hearing.
The aim of the study is twofold:
1) to define the nature of the problem and
2) to assess a variety of mitigating measures.
The majority of work on cycling-related aeroacoustics has focused on wind-noise as a nuisance or distraction. In addition to this, the current proposal considers the potential threat to hearing conservation.
It is well known that wind-noise can lead to hearing loss in motorcyclists
but there is no known research into potential wind-induced hearing problems
for pedal cyclists. In addition, recent history has seen reports of hearing-related
problems such as tinnitus appearing on internet cycling forums, with some
bicycle riders postulating that these problems may have been caused, at
least in part, by prolonged exposure to 'wind noise'.
In the United Kingdom an increasing number of journeys are being made
by pedal cycle both for commuting and leisure. People are drawn to
cycling for economic, environmental, social and health reasons. These
factors are currently regarded as important and the Conservative government
actively supports the increased use of pedal cycles by, for example,
by providing a Cycle to Work scheme, which is part of their Green
Transport Plan.
Airflow around a cyclist in motion is a viscous-dominated regime characterized
by flow-separation. Separated flow and associated turbulence leads to
a significant increase in the magnitude of the aeroacoustic signal. This
is relatively easy to appreciate if, while riding, the cyclist's head
is turned to face the side (ensuring that this is done in a wide open
space, with no obstacles or other vehicles present). In this position,
with one ear pointing directly into the incident flow, and the other in
the head's wake flow, both pinnae are well away from the point of flow
separation and 'wind noise' is greatly reduced.
Kristiansen and Pettersen(1) measured the noise heard by human beings
exposed to atmospheric winds under controlled conditions. Through flow
visualization and aerodynamic pressure measurements they found that the
relatively high noise heard when looking directly into a wind has its
origin in wake flow fluctuation created by flow separation at about the
position of the cheekbone. The average person facing a 21 mile per hour
wind experiences noise within the range 25 – 150 Hz at an intensity
of 92 db above the quiet hearing threshold. It is well known that hearing
damage is directly related to both noise intensity and duration and this
figure of 92 db is above the HSE daily exposure limit.
The proposed study will quantify the performance of existing devices
(such as the Slipstreamz Spoiler) in reducing aeroacoustic noise.
It will also assess the effectiveness of novel designs. The emphasis
will be on simplicity, looking at mitigating measures that are the
most likely to be adopted by cyclists and optimizing them.
Through the use of an instrumented test model it is proposed that the
characteristic nature and magnitude of the aeroacoustic signal generated
at a cyclist’s ear are investigated. Tests will be conducted at
various incident wind speeds and cyclist geometry. Assessments will be
made of methods to reduce the effect of wind noise while maintaining a
cyclist's ability to hear traffic, for example, by the use of ‘acoustically-transparent’
wind-mufflers similar to those used on microphones in the film industry.
Background Information on hearing loss from the UK Biobank:
Hearing loss is a common problem. There are around 10 million people with
hearing loss in the UK and this is forecast to increase to 14.5 million
by 2031. Around 25% of participants who joined UK Biobank reported difficulties
with hearing, which can have a profound impact on emotional, social and
physical well-being. Hearing loss receives relatively little research
attention (in 2010, £1.34 research money spent per person affected,
compared to £14.31 for vision and £49.71 for cardiovascular
research). Dr Piers Dawes from the School of Psychological Sciences at
the University of Manchester said: “Almost everyone will experience
hearing loss as they grow older; it is a big problem and will get worse.”
Sport England's Active People Survey - 29th January 2015
In January 2015 the results from Sport England's Active People survey
revealed that over 100,000 more cyclists are riding bikes at least once
a week than were in October 2012. The news brings the total number of
regular adult cyclists to more than two million and cycling remains the
third most popular sport in England. Welcoming the news, British Cycling's
chief executive, Ian Drake, said: "The appetite we're seeing for
cycling in this country is at an all-time high. Over two years on from
London 2012, and with a fantastic Tour de France behind us, we are still
seeing a steady increase in the number of people getting on bikes."
