Basso continuo is a baroque improvisatory accompaniment style which involves improvising multiple parts above a given bass line in a musical score on a harpsichord or organ. Basso continuo is not merely a matter of history; moreover, it is a historically inspired living practice, and The Aligned Continuo Dataset (ACoRD) records the first sample of modern-day basso continuo playing in the symbolic domain. This dataset, containing 175 MIDI recordings of 5 basso continuo scores performed by 7 players, allows us to start observing and analyzing the variety that basso continuo improvisation brings. A recently proposed basso continuo performance-to-score alignment system provides a way of mapping improvised performance notes to score notes. In order to study aligned basso continuo performances, we need an appropriate feature representation. We propose griff, a representation inspired by historical basso continuo treatises. It enables us to encode both pitch content and structure of a basso continuo realization in a transposition-invariant way. Griffs are directly extracted from aligned basso continuo performances by grouping together performance notes aligned to the same score note in a onset-time ordered way, and they provide meaningful tokens that form a feature space in which we can analyze basso continuo performance styles. We statistically describe griffs extracted from the ACoRD dataset recordings, and show in two experiments how griffs can be used for statistical analysis of individuality of different players' basso continuo performance styles. We finally present an argument why it is desirable to preserve the structure of a basso continuo improvisation in order to conduct a refined analysis of personal performance styles of individual basso continuo practitioners, and why griffs can provide a meaningful historically informed feature space worthy of a more robust empirical validation.

翻译：通奏低音是一种巴洛克时期的即兴伴奏风格，要求演奏者在大键琴或管风琴上根据乐谱中给定的低音线条即兴演奏出多个声部。通奏低音不仅具有历史意义，更是一种受历史启发的、鲜活的实践；《对齐通奏低音数据集》（ACoRD）首次在符号领域记录了现代通奏低音演奏的样本。该数据集包含7位演奏者对5首通奏低音乐谱的175段MIDI录音，使我们得以开始观察和分析通奏低音即兴演奏所带来的多样性。最近提出的通奏低音演奏-乐谱对齐系统，提供了一种将即兴演奏音符映射到乐谱音符的方法。为了研究对齐后的通奏低音演奏，我们需要一种合适的特征表征。我们提出“指法组合”（griff）这一表征，其灵感来源于历史上的通奏低音论著。它使我们能够以移调不变的方式编码通奏低音实现的音高内容与结构。指法组合直接从对齐的通奏低音演奏中提取，方法是将对齐到同一乐谱音符的演奏音符按起始时间顺序分组，从而提供有意义的标记，构成一个可用于分析通奏低音演奏风格的特征空间。我们对从ACoRD数据集录音中提取的指法组合进行了统计描述，并通过两个实验展示了如何利用指法组合对不同演奏者的通奏低音演奏风格进行个体性的统计分析。最后，我们论证了为何需要保留通奏低音即兴演奏的结构，以便对个体演奏者的个人演奏风格进行精细分析，以及为何指法组合能够提供一个有意义的、基于历史知识的特征空间，值得进行更稳健的实证验证。