Hearing is believing

Novel developments in electronics which are giving ecologists important new tools to quickly and easily measure biodiversity will be described at the British Ecological Society’s Winter Meeting, being held at the University of York on 18–20 December 2002.

Speaking at the meeting, electronics expert and entomologist Dr David Chesmore from the University of York will explain a novel method of identifying different grasshopper species using time domain signal coding and artificial neural networks, instead of the more traditional magnifying glass and field guide.

Together with entomologist Eiji Ohya from the Forestry and Forest Products Institute in Morioka, Japan, Dr Chesmore has been developing ways of automatically identifying different grasshopper species by analysing their calls. According to Dr Chesmore: “Initial results are promising, and we can now reliably discriminate between the four commonly-occurring species of grasshopper in Yorkshire, six species of cricket and bush cricket in Japan, and other sounds such as bird song and man-made sounds. Previously, we have been able to discriminate between 23 species in the UK using high quality recordings but this is the first time we have extensively used field recordings.”

Time domain signal coding is a type of signal processing which allows scientists to pick out particular characteristics from a sound. Feeding the signal into an artificial neural network then allows a computer to be trained to identify the different grasshopper calls. In the current version, the artificial neural network has been trained with the four grasshopper sounds, three bird species, vehicle and aircraft sounds. Early results show that the system can recognise all the sound types under varying acoustic conditions.

Dr Chesmore believes that such automated bioacoustic systems for species identification and rapid biodiversity assessment will become increasingly important ecological tools. “It is feasible to develop hand-held recognisers and remotely-sited continuous monitors. I am currently developing a hand-held recogniser for British bats, and will be returning to Japan in March 2003 to work on continuous recognition of bird species,” he says.

Dr David Chesmore will present his full findings at 09:20 on Thursday 19 December 2002.