Band Prompting Aided SAR and Multi-Spectral Data Fusion Framework for Local Climate Zone Classification

Local climate zone (LCZ) classification is of great value for understanding the complex interactions between urban development and local climate. Recent studies have increasingly focused on the fusion of synthetic aperture radar (SAR) and multi-spectral data to improve LCZ classification performance. However, it remains challenging due to the distinct physical properties of these two types of data and the absence of effective fusion guidance. In this paper, a novel band prompting aided data fusion framework is proposed for LCZ classification, namely BP-LCZ, which utilizes textual prompts associated with band groups to guide the model in learning the physical attributes of different bands and semantics of various categories inherent in SAR and multi-spectral data to augment the fused feature, thus enhancing LCZ classification performance. Specifically, a band group prompting (BGP) strategy is introduced to align the visual representation effectively at the level of band groups, which also facilitates a more adequate extraction of semantic information of different bands with textual information. In addition, a multivariate supervised matrix (MSM) based training strategy is proposed to alleviate the problem of positive and negative sample confusion by completing the supervised information. The experimental results demonstrate the effectiveness and superiority of the proposed data fusion framework.

Hierarchical Metadata Information Constrained Self-Supervised Learning for Anomalous Sound Detection Under Domain Shift

Self-supervised learning methods have achieved promising performance for anomalous sound detection (ASD) under domain shift, where the type of domain shift is considered in feature learning by incorporating section IDs. However, the attributes accompanying audio files under each section, such as machine operating conditions and noise types, have not been considered, although they are also crucial for characterizing domain shifts. In this paper, we present a hierarchical metadata information constrained self-supervised (HMIC) ASD method, where the hierarchical relation between section IDs and attributes is constructed, and used as constraints to obtain finer feature representation. In addition, we propose an attribute-group-center (AGC)-based method for calculating the anomaly score under the domain shift condition. Experiments are performed to demonstrate its improved performance over the state-of-the-art self-supervised methods in DCASE 2022 challenge Task 2.

Local Information Assisted Attention-free Decoder for Audio Captioning

Automated audio captioning (AAC) aims to describe audio data with captions using natural language. Most existing AAC methods adopt an encoder-decoder structure, where the attention based mechanism is a popular choice in the decoder (e.g., Transformer decoder) for predicting captions from audio features. Such attention based decoders can capture the global information from the audio features, however, their ability in extracting local information can be limited, which may lead to degraded quality in the generated captions. In this paper, we present an AAC method with an attention-free decoder, where an encoder based on PANNs is employed for audio feature extraction, and the attention-free decoder is designed to introduce local information. The proposed method enables the effective use of both global and local information from audio signals. Experiments show that our method outperforms the state-of-the-art methods with the standard attention based decoder in Task 6 of the DCASE 2021 Challenge.