18 research outputs found
Transfer Learning and Bias Correction with Pre-trained Audio Embeddings
Deep neural network models have become the dominant approach to a large
variety of tasks within music information retrieval (MIR). These models
generally require large amounts of (annotated) training data to achieve high
accuracy. Because not all applications in MIR have sufficient quantities of
training data, it is becoming increasingly common to transfer models across
domains. This approach allows representations derived for one task to be
applied to another, and can result in high accuracy with less stringent
training data requirements for the downstream task. However, the properties of
pre-trained audio embeddings are not fully understood. Specifically, and unlike
traditionally engineered features, the representations extracted from
pre-trained deep networks may embed and propagate biases from the model's
training regime. This work investigates the phenomenon of bias propagation in
the context of pre-trained audio representations for the task of instrument
recognition. We first demonstrate that three different pre-trained
representations (VGGish, OpenL3, and YAMNet) exhibit comparable performance
when constrained to a single dataset, but differ in their ability to generalize
across datasets (OpenMIC and IRMAS). We then investigate dataset identity and
genre distribution as potential sources of bias. Finally, we propose and
evaluate post-processing countermeasures to mitigate the effects of bias, and
improve generalization across datasets.Comment: 7 pages, 3 figures, accepted to the conference of the International
Society for Music Information Retrieval (ISMIR 2023
Astronomical verification of a stabilized frequency reference transfer system for the Square Kilometre Array
In order to meet its cutting-edge scientific objectives, the Square Kilometre
Array (SKA) telescope requires high-precision frequency references to be
distributed to each of its antennas. The frequency references are distributed
via fiber-optic links and must be actively stabilized to compensate for
phase-noise imposed on the signals by environmental perturbations on the links.
SKA engineering requirements demand that any proposed frequency reference
distribution system be proved in "astronomical verification" tests. We present
results of the astronomical verification of a stabilized frequency reference
transfer system proposed for SKA-mid. The dual-receiver architecture of the
Australia Telescope Compact Array was exploited to subtract the phase-noise of
the sky signal from the data, allowing the phase-noise of observations
performed using a standard frequency reference, as well as the stabilized
frequency reference transfer system transmitting over 77 km of fiber-optic
cable, to be directly compared. Results are presented for the fractional
frequency stability and phase-drift of the stabilized frequency reference
transfer system for celestial calibrator observations at 5 GHz and 25 GHz.
These observations plus additional laboratory results for the transferred
signal stability over a 166 km metropolitan fiber-optic link are used to show
that the stabilized transfer system under test exceeds all SKA phase-stability
requirements under a broad range of observing conditions. Furthermore, we have
shown that alternative reference dissemination systems that use multiple
synthesizers to supply reference signals to sub-sections of an array may limit
the imaging capability of the telescope.Comment: 12 pages, accepted to The Astronomical Journa
Improving Differential Amplifier Rejection Ratios
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69994/2/RSINAK-21-8-770-1.pd
Analysis And Synthesis Of Electrocardiographic Leads.
PhDElectrical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/181450/2/0011319.pd