Impulsive sound quality of tennis rackets
Guy Banwell
2134/13678
https://repository.lboro.ac.uk/articles/thesis/Impulsive_sound_quality_of_tennis_rackets/9526433
The sound radiated during a tennis impact has been shown to greatly influence the perception of
‘feel’ but has also been suggested to contribute to the perception of equipment quality, as is the
case with many other consumer products. In an industry that is governed by design limitations,
tennis racket manufactures are continually aiming to differentiate their products from their
competitors’ and the sound character of a racket is seen as one such method to do so.
In order to control the sound radiated from a tennis racket it was first necessary to identify how
a tennis racket radiates sound. Through a number of controlled player tests, involving
groundstrokes and serves, the sound was recorded along with measurements of the physical
vibrations excited in the frame. Analysis of the data revealed typical characteristics of the sound
in the time and frequency domain. The sound was split into two sections to aid the analysis; an
initial impulsive component that decayed very quickly and a ringing component that was of much
lower amplitude but decayed at a much slower rate. The evolution of the frequency content
over time was also investigated, however, the data provided much more information as to where
each frequency component originated by analysing the data together with the experimental
modal analysis data.
The experimental modal analysis of a tennis racket was a vital stage in understanding which
components of the racket were responsible for radiating the identified frequency component in
the sound spectrum. The investigations identified frame bending modes, out-of-plane and inplane,
as well as torsional modes, hoop modes and stringbed modes. To enable direct
comparison between the natural frequencies excited during a tennis shot and the frequencies
recorded from a freely suspended racket, the effect of the hand on the modal behaviour of the
racket was analysed; experimental modal analysis data from a hand-gripped racket was compared
with data generated by adding simulated mass to the modal model of the freely suspended racket.
The first stringbed mode was identified as a key contributor to the sound of the racket, especially
in the ringing component of the sound. Analysis of the physical vibrations in the frame following
a tennis shot revealed that the first stringbed mode excited the frame of the racket, which is
iv
thought to be the reason why stringbed modes contribute to the sound more so than their
surface area would suggest that they are capable of.
Analysis of the relationship between subjective perceptions of players and calculated sound
metrics suggest a negative correlation exists between the duration and loudness of a tennis shot
and the appeal of the sound. Further investigations involving a jury to evaluate the appeal of a
tennis impact sound, modified in terms of duration, revealed further evidence to support the
theory that tennis impact sounds of greater duration are less appealing than those that decay
quickly.
This is the first study to investigate the sound radiated from a tennis racket and has identified
how the sound is radiated from the racket and also suggests which parameters of the sound are
considered appealing to tennis players. With this information it is possible to suggest design
modifications that would influence the sound of a tennis racket in a predictable manner.
2013-11-27 09:13:08
Tennis
Acoustics
Perception
Dynamics
Modal analysis
Mechanical Engineering not elsewhere classified