Recent automated transcription systems have focused on end-to-end orthographic approaches driven by deep neural networks and sequence-to-sequence transformers. Growing public interest in transcription at the phonemic or phonetic level has led to re-purposing these systems to segment and identify phones, the basic sounds which comprise human speech. However, they miss the mark on a fundamental component of time-series analysis, namely time. For linguistic applications which require high fidelity in the temporal domain, the loss of timing information is untenable. Our work proposes a deadline-bounded expectation maximization (EM) algorithm with a novel initialization method to estimate formants, i.e., salient speech frequencies, for enhanced phonetic segmentation. Based on the concept of spectral gravity, i.e., treating spectral energy as mass attenuated by the square of frequency distance across the spectrum, our technique outperforms the recent state of the art on key clustering metrics, generating reasonable alignments across multiple languages with no a priori training.

Phonetic transcription requires significant time and expert training. Automated, state-of-the-art text-dependent methods still involve substantial pre-training annotation labor and may not generalize to multiple languages. Hallucination of speech amid silence or non-speech noise can also plague these methods, which fall short in real-time applications due to post hoc whole-phrase evaluation. This paper introduces Phonotomizer, a compact, unsupervised, online training approach to automatic, multilingual phonetic segmentation, a critical first stage in transcription. Unlike prior approaches, Phonotomizer trains on raw sound files alone and can modulate computational exactness. Preliminary evaluations on Irish and Twi, two underrepresented languages, exhibit segmentation comparable to current forced alignment technology, reducing acoustic model size and minimizing training epochs.