Tools for measuring pitch and comparing vocalizations. Features include:
Keen SC, Meliza CD, Rubenstein DR (2013). Flight calls signal group and individual identity but not kinship in a cooperatively breeding bird. Behavioral Ecology, doi:10.1093/beheco/art062
Meliza CD, Keen SC, Rubenstein DR (2013). Pitch- and spectral-based time warping methods for comparing field recordings of harmonic avian vocalizations. Journal of the Acoustical Society of America, doi:10.1121/1.4812269
Time-frequency reassignment is a technique for sharpening spectrographic representations of sounds (see figure). For relatively simple, non-stationary processes, TFR can provide substantial improvements in detecting fine structure. Further improvements can be realized by using multiple windowing functions (similar to the multitaper method for calculating the spectra of stationary processes), but the algorithms are computationally intensive. libtfr is a library for calculating multitaper TFR spectrograms which is implemented in C and uses the highly efficient FFTW library. It also supports calculating standard multitaper spectrograms and spectra, and comes with python/numpy and MATLAB interfaces.
Vocalizations often consist of spectrotemporally disjoint, discrete elements, and it's often desirable to extract and manipulate these elements separately. However, because they often overlap temporally, the separation can only be achieved in the spectrotemporal domain. znote is a software package for identifying components in bioacoustic signals and extracting the sound pressure waveforms associated with them.
Hosted on GitHub: melizalab/znote
Meliza CD, Chi Z, Margoliash D (2010). Representations of Conspecific Song by Starling Secondary Forebrain Auditory Neurons: Towards a Hierarchical Framework. J Neurophysiology, doi:10.1152/jn.00464.2009