Acoustic analysis of tennis grunting
Maria Sharapova and Victoria Azarenka are probably the most informous tennis grunters, but Maria Sharapova’s vocalisations are the most extreme. They are often quoted as being the loudest, with one cry being recorded at 105 decibels in 2009. 
The spectrogram below shows 4 grunts, 2 from each player. The first is from Sharapova and happens at the left side of the graph. A spectrogram shows how the frequency of sound varies over time, in this case bright red indicates strong parts of the sound and blue weak bits. The bright red line drooping down from left to right shows how the frequency of the Sharapova’s cry starts at about 900 Hz and drops to about 600 Hz in about a third of a second.
The frequencies are well above the normal female speaking range, and are more characteristic of soprano singers. Apart from shear sound level in decibels, these high frequencies are one of the acoustic features that probably make the grunt particularly annoying. In acoustic engineering chirps are often used in measurement because they can be picked out against background noise. Whip birds in Australia use a similar trick:
Comparing the spectrograms, the whip-bird’s downward chirp (right side of the above plot) is over a larger frequency range going from 3000 to 500 Hz and happens much faster than Sharapova’s grunt. The vocal athleticism of the whip-bird is remarkable, honed to perfection as females probably listen to the quality of the chirp when selecting a mate.
Sharapova’s grunt is also amplified and elongated by the Wimbledon roof when it is closed, see How the Centre Court roof changes the sound at Wimbledon.
Which other players have annoying grunts I could analyse?
 http://www.independent.co.uk/sport/tennis/wimbledon-2013-the-secret-of-andy-murrays-success-knowing-when-to-admit-defeat-8670422.htmlFollow me