Hanna Järveläinen

Audibility of the timbral effects of inharmonicity in stringed instrument tones

Listening tests were conducted to find the audibility of inharmonicity in musical sounds produced by stringed instruments, such as the piano or the guitar. The audibility threshold of inharmonicity was measured at five fundamental frequencies. Results show that the detection of inharmonicity is strongly dependent on the fundamental frequency f0. A simple model is presented for estimating the threshold as a function of f0. The need to implement inharmonicity in digital sound synthesis is discussed.

Perception and Adjustment of Pitch in Inharmonic String Instrument Tones

The effect of inharmonicity on pitch was measured by listening tests at five fundamental frequencies. Inharmonicity was defined in a way typical of string instruments, such as the piano, where all partials are elevated in a systematic way. It was found that the pitch judgment is usually dominated by some other partial than the fundamental; however, with a high degree of inharmonicity the fundamental became important as well. Guidelines are given for compensating for the pitch difference between harmonic and inharmonic tones in digital sound synthesis.

Detection of keyboard vibrations and effects on perceived piano quality

Two experiments were conducted on an upright and a grand piano, both either producing string vibrations or conversely being silent after the initial keypress, while pianists were listening to the feedback from a synthesizer through insulating headphones. In a quality experiment, participants unaware of the silent mode were asked to play freely and then rate the instrument according to a set of attributes and general preference. Participants preferred the vibrating over the silent setup, and preference ratings were associated to auditory attributes of richness and naturalness in the low and middle ranges. Another experiment on the same setup measured the detection of vibrations at the keyboard, while pianists played notes and chords of varying dynamics and duration. Sensitivity to string vibrations was highest in the lowest register and gradually decreased up to note D5. After the percussive transient, the tactile stimuli exhibited spectral peaks of acceleration whose perceptibility was demonstrated by tests conducted in active touch conditions. The two experiments confirm that piano performers perceive vibratory cues of strings mediated by spectral and spatial summations occurring in the Pacinian system in their fingertips, and suggest that such cues play a role in the evaluation of quality of the musical instrument.

Perception of Vibrotactile Cues in Musical Performance

We suggest that studies on active touch psychophysics are needed to inform the design of haptic musical interfaces and better understand the relevance of haptic cues in musical performance. Following a review of the previous literature on vibrotactile perception in musical performance, two recent experiments are reported. The first experiment investigated how active finger-pressing forces affect vibration perception, finding significant effects of vibration type and force level on perceptual thresholds. Moreover, the measured thresholds were considerably lower than those reported in the literature, possibly due to the concurrent effect of large (unconstrained) finger contact areas, active pressing forces, and long-duration stimuli. The second experiment assessed the validity of these findings in a real musical context by studying the detection of vibrotactile cues at the keyboard of a grand and an upright piano. Sensitivity to key vibrations in fact not only was highest at the lower octaves and gradually decreased toward higher pitches; it was also significant for stimuli having spectral peaks of acceleration similar to those of the first experiment, i.e., below the standard sensitivity thresholds measured for sinusoidal vibrations under passive touch conditions.