Secondary Tonal Analyses: Order Without Theory
Based on these generated pitch events, the system performs several further so-called static tonal analyses. These are not intended to identify classical keys or scales, but rather to extract statistical properties of the material.
One central element is the tuning analysis. Because the conversion of frequencies into MIDI notes always requires a reference frequency, the system checks for each detected note which reference tuning within a range of approximately 420 to 450 Hz produces the smallest deviation. The reference frequency that most frequently yields the best match across all notes is assumed to be the tuning of the entire original recording. This method is deliberately approximate and error-prone, but it is nevertheless considered meaningful, as it provides at least a rough approximation of historical or regional tunings.
In addition, the system collects all generated pitch values and evaluates their frequency of occurrence. The five most frequently occurring pitches are interpreted as the individual scale of the recording, while the most frequent pitch is defined as the fundamental tone. No statement is made about the internal structure of this scale. It may be incomplete, microtonal, or internally inconsistent. This openness is an explicit part of the concept.
Furthermore, the system analyzes the duration of the generated pitch events. The longest stable tones are of particular interest, as they often possess a clear and sustained sonic character. These data are later used for the extraction of samples.
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