What is it about?

A large number of the vocalization studies on mammals are based on time-frequency analysis of the produced sounds. The patterns, which are extracted from the time-frequency representations, determine the classification in the different sound categories. However, there are situations where this pattern related recognition does not allow a precise characterization of the vocalization to be obtained. In these situations, a feasible alternative, which can help by giving the dominant component of the sound, is to measure the strength of the tonal and pulsed constituent units. In this work, the use of a ratio of pulsed to tonal strength is proposed to objectively measure the distribution of energy between these two components. This pulsed to tonal ratio (PTR) can be computed with the aid of the discrete cosine transform. It is demonstrated that the PTR can be obtained with a relatively simple expression without having to go through the time- frequency representation. This work presents examples that show how the PTR can be used to distinguish between two very similar Beluga whale sounds and how to dynamically track the power distribution between the pulsed and tonal components in non-stationary signals.

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Why is it important?

An optimised algorithm to compute the metric is proposed so that it is not computationally very demanding and can run in real time.


The proposed metric can also be used as a pre-detector of pulsed or tonal activity in passive acoustic monitoring or aerial sounds.

Ramon Miralles
Universitat Politecnica de Valencia

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This page is a summary of: The pulsed to tonal strength parameter and its importance in characterizing and classifying Beluga whale sounds, The Journal of the Acoustical Society of America, March 2012, Acoustical Society of America (ASA), DOI: 10.1121/1.3682056.
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