There are 2 repositories under audio-annotation-tool topic.
A curated list of awesome data labeling tools
Cicada is an open source audio annotation tool that lets you annotate audio files in .wav format and also enables you to look into each audio spectrogram while annotating
Pyrenote, the Audio Labeling System for Acoustics Specifies Identification Project, is built to generate human moment-to-moment labels on audio files. At present, being used to label bird audio data. Derived from the open source repo Audino
Web-based tool for straight-forward class annotation of audio files