Vincent Kather - Academia.edu (original) (raw)
Papers by Vincent Kather
The Journal of the Acoustical Society of America/The journal of the Acoustical Society of America, Mar 1, 2024
The study of humpback whale song using passive acoustic monitoring devices requires bioacousticia... more The study of humpback whale song using passive acoustic monitoring devices requires bioacousticians to manually review hours of audio recordings to annotate the signals. To vastly reduce the time of manual annotation through automation, a machine learning model was developed. Convolutional neural networks have made major advances in the previous decade, leading to a wide range of applications, including the detection of frequency modulated vocalizations by cetaceans. A large dataset of over 60 000 audio segments of 4 s length is collected from the North Atlantic and used to fine-tune an existing model for humpback whale song detection in the North Pacific (see Allen, Harvey, Harrell, Jansen, Merkens, Wall, Cattiau, and Oleson (2021). Front. Mar. Sci. 8, 607321). Furthermore, different data augmentation techniques (time-shift, noise augmentation, and masking) are used to artificially increase the variability within the training set. Retraining and augmentation yield F-score values of 0.88 on context window basis and 0.89 on hourly basis with false positive rates of 0.05 on context window basis and 0.01 on hourly basis. If necessary, usage and retraining of the existing model is made convenient by a framework (AcoDet, acoustic detector) built during this project. Combining the tools provided by this framework could save researchers hours of manual annotation time and, thus, accelerate their research.
The SPRAWL system is an audio and information routing network,enabling enhanced ways of interacti... more The SPRAWL system is an audio and information routing network,enabling enhanced ways of interaction for musical ensembles. ALinux audio server with a SuperCollider mixing and spatializationsystem is connected to several access points via ethernet, using Jack-Trip for audio transmission. The unified access points are based ona Raspberry Pi 4 with a 7 inch touch screen and a USB audio in-terface, running SuperCollider, Puredata and additional tools. Usingcustom applications on these units, musicians are able to control therouting and spatialization of the system, allowing personal monitor-ing, the distribution of click tracks and related auditory information,as well as visual information and cues. The system is designed asa meta-instrument for developing individual configurations and soft-ware components for specific compositions and use cases. It hasbeen successfully used in on-site concerts and ported to wide areanetworks for remote rehearsals and performances.
International Journal of Spray and Combustion Dynamics
The generation and turbulent transport of temporal equivalence ratio fluctuations in a swirl comb... more The generation and turbulent transport of temporal equivalence ratio fluctuations in a swirl combustor are experimentally investigated and compared to a one-dimensional transport model. These fluctuations are generated by acoustic perturbations at the fuel injector and play a crucial role in the feedback loop leading to thermoacoustic instabilities. The focus of this investigation lies on the interplay between fuel fluctuations and coherent vortical structures that are both affected by the acoustic forcing. To this end, optical diagnostics are applied inside the mixing duct and in the combustion chamber, housing a turbulent swirl flame. The flame was acoustically perturbed to obtain phase-averaged spatially resolved flow and equivalence ratio fluctuations, which allow the determination of flux-based local and global mixing transfer functions. Measurements show that the mode-conversion model that predicts the generation of equivalence ratio fluctuations at the injector holds for line...
The Journal of the Acoustical Society of America/The journal of the Acoustical Society of America, Mar 1, 2024
The study of humpback whale song using passive acoustic monitoring devices requires bioacousticia... more The study of humpback whale song using passive acoustic monitoring devices requires bioacousticians to manually review hours of audio recordings to annotate the signals. To vastly reduce the time of manual annotation through automation, a machine learning model was developed. Convolutional neural networks have made major advances in the previous decade, leading to a wide range of applications, including the detection of frequency modulated vocalizations by cetaceans. A large dataset of over 60 000 audio segments of 4 s length is collected from the North Atlantic and used to fine-tune an existing model for humpback whale song detection in the North Pacific (see Allen, Harvey, Harrell, Jansen, Merkens, Wall, Cattiau, and Oleson (2021). Front. Mar. Sci. 8, 607321). Furthermore, different data augmentation techniques (time-shift, noise augmentation, and masking) are used to artificially increase the variability within the training set. Retraining and augmentation yield F-score values of 0.88 on context window basis and 0.89 on hourly basis with false positive rates of 0.05 on context window basis and 0.01 on hourly basis. If necessary, usage and retraining of the existing model is made convenient by a framework (AcoDet, acoustic detector) built during this project. Combining the tools provided by this framework could save researchers hours of manual annotation time and, thus, accelerate their research.
The SPRAWL system is an audio and information routing network,enabling enhanced ways of interacti... more The SPRAWL system is an audio and information routing network,enabling enhanced ways of interaction for musical ensembles. ALinux audio server with a SuperCollider mixing and spatializationsystem is connected to several access points via ethernet, using Jack-Trip for audio transmission. The unified access points are based ona Raspberry Pi 4 with a 7 inch touch screen and a USB audio in-terface, running SuperCollider, Puredata and additional tools. Usingcustom applications on these units, musicians are able to control therouting and spatialization of the system, allowing personal monitor-ing, the distribution of click tracks and related auditory information,as well as visual information and cues. The system is designed asa meta-instrument for developing individual configurations and soft-ware components for specific compositions and use cases. It hasbeen successfully used in on-site concerts and ported to wide areanetworks for remote rehearsals and performances.
International Journal of Spray and Combustion Dynamics
The generation and turbulent transport of temporal equivalence ratio fluctuations in a swirl comb... more The generation and turbulent transport of temporal equivalence ratio fluctuations in a swirl combustor are experimentally investigated and compared to a one-dimensional transport model. These fluctuations are generated by acoustic perturbations at the fuel injector and play a crucial role in the feedback loop leading to thermoacoustic instabilities. The focus of this investigation lies on the interplay between fuel fluctuations and coherent vortical structures that are both affected by the acoustic forcing. To this end, optical diagnostics are applied inside the mixing duct and in the combustion chamber, housing a turbulent swirl flame. The flame was acoustically perturbed to obtain phase-averaged spatially resolved flow and equivalence ratio fluctuations, which allow the determination of flux-based local and global mixing transfer functions. Measurements show that the mode-conversion model that predicts the generation of equivalence ratio fluctuations at the injector holds for line...