RESUMEN

Human listeners prefer octave intervals slightly above the exact 2:1 frequency ratio. To study the neural underpinnings of this subjective preference, called the octave enlargement phenomenon, we compared neural responses between exact, slightly enlarged, oversized, and compressed octaves (or their multiples). The first experiment (n = 20) focused on the N1 and P2 event-related potentials (ERPs) elicited in EEG 50-250 ms after the second tone onset during passive listening of one-octave intervals. In the second experiment (n = 20) applying four-octave intervals, musician participants actively rated the different octave types as 'low', 'good' and 'high'. The preferred slightly enlarged octave was individually determined prior to the second experiment. In both experiments, N1-P2 peak-to-peak amplitudes attenuated for the exact and slightly enlarged octave intervals compared with compressed and oversized intervals, suggesting overlapping neural representations of tones an octave (or its multiples) apart. While there were no differences between the N1-P2 amplitudes to the exact and preferred enlarged octaves, ERP amplitudes differed after 500 ms from onset of the second tone of the pair. In the multivariate pattern analysis (MVPA) of the second experiment, the different octave types were distinguishable (spatial classification across electroencephalography [EEG] channels) 200 ms after second tone onset. Temporal classification within channels suggested two separate discrimination processes peaking around 300 and 700 ms. These findings appear to be related to active listening, as no multivariate results were found in the first, passive listening experiment. The present results suggest that the subjectively preferred octave size is resolved at the late stages of auditory processing.

Asunto(s)

Potenciales Evocados , Música , Humanos , Psicoacústica , Electroencefalografía , Percepción Auditiva/fisiología , Potenciales Evocados Auditivos/fisiología , Estimulación Acústica

RESUMEN

The consensus in piano tuning philosophy explains the stretched tuning scale by the inharmonicity of piano strings. This study aimed to examine how variable inharmonicity influences the result of the piano tuning process, compare the tuning curves of aurally tuned pianos with the curves derived from subjective octave enlargement experiments, and evaluate whether the pitches of inharmonic or harmonic versions of the same tone are perceived differently. In addition, the influence of strings of other piano keys on the measured inharmonicity of a single piano string was investigated. The inharmonicity of all individual strings was measured on a Steinway D grand piano. Variable inharmonicity was implemented by additive synthesis with frequency-adjusted sinusoidal partials. Fifteen piano tuners and 18 orchestra musicians participated in the experiments. The results indicate that the inharmonic piano tones produced a keyboard tuning curve similar to the Railsback curve and differed significantly from the harmonic counterpart. The inharmonic tuning curve was reminiscent of the subjective octave enlargement curve. Inharmonic tone pitches were perceived to be higher than harmonic tones up to C ♯ 7. The covibrating strings of the other keys did not exhibit any meaningful effect on the measured inharmonicity of a single string of the played key.

Asunto(s)

Música , Percepción de la Altura Tonal

RESUMEN

For decades, the phenomenon of subjectively enlarged octaves has been investigated using sinusoidal and synthesized complex tones. The present study elaborates the topic with samples of real orchestra instruments in successive tone listening experiments. Compared to previous research, this study also included a substantially larger number of subjects (N = 36). Examined instrument tones were categorized into five groups based on their acoustic principles. In addition, each group was assessed at three dynamic levels (pp-mf-ff). Collected data were analyzed with tuning stretch curves by applying generalized additive models in the manner of the Railsback curve used to characterize piano tuning. Although the tuning curve modeled for the orchestra instruments was observed to differ slightly from the Railsback curve and typical Steinway D grand piano tuning (Steinway, New York), the stretching trends were qualitatively similar. Deviation from a mathematical equal-tempered scale was prominent. According to statistical analyses, dynamics or musical background of the participant did not affect results significantly, but some instrument groups exhibited differences in the curve extremities. In conclusion, the stretched scale is natural for a human listener and should be used as a reference scale in tuning machines instead of the mathematical equal-tempered scale.