Proposed tuning progression curves for Celeste ranks in the range C₂…C₈ . The dotted curves represent one JNVF and 2∙JNVF. The dashed curve depicts the beat frequency (BF) proposed for Accordion Celestes [25], which rises linearly with pitch for low frequencies (indicated by the dashed straight line) and increases exponentially with pitch (Δf = 0.003∙f) in the treble where it approximates variant b). To facilitate a comparison between the effects of doubling the beat frequency slower than each octave (variants (b) and (c)), namely every 1.5 octaves, the dash-dotted curves have been included.