When we listen to a song or musical performance, out-of-tune singers or instruments are generally perceived as unpleasant for listeners. While it is well-established that mistuning can reduce the enjoyment of music, the processes influencing how humans perceive mistuning have not yet been fully delineated.

Researchers at the University of Minnesota recently carried out a study aimed at better understanding factors influencing the extent to which individuals can perceive mistuning in natural music. their findings, published in Communication Psychologyhighlight acoustic elements that influence the perception of dissonance when hearing out-of-tune singing voices or instruments.

“An out-of-tune singer or instrument can ruin the enjoyment of music,” Sara MK Madsen and Andrew J. Oxenham wrote in their paper. “However, there is disagreement on how we perceive mistuning in natural music settings. To address this question, we presented listeners with in-tune and out-of-tune passages of two-part music and manipulated the two primary candidate acoustic cues: beats (fluctuations caused by interactions between nearby frequency components) and inharmonicity (non-integer harmonic frequency relationships) across seven experiments.”

To explore the acoustic underpinnings of the dissonance linked to mistuning, Madsen and Oxenham carried out a series of experiments involving different groups of participants. Their experiments involved 101, 62, 87, 28, 69, 160, and 105 participants, respectively, all recruited via Amazon Mechanical Turk.

Each participant listened to musical segments in which instruments were either in tune or out of tune with each other. After every experimental trial, they were asked if they thought the music they heard was in tune or out of tune.

The researchers manipulated two key acoustic elements of the musical sequences, namely the beats and inharmonicity. They then tried to determine whether the participants’ ability to recognize mistuning was affected by manipulating these two acoustic cues.

Interestingly, the researchers observed that both these acoustic elements played a key part in the participants’ ability to detect mistuning between different parts of musical sequences. In particular, the strength of beats appeared to be closely linked to people’s ability to perceive mistuning.

“Mistuning detection worsened markedly when removing either beating or inharmonicity cues, suggesting important contributions from both,” wrote Madsen and Oxenham. “The relative importance of the two cues varied reliably between listeners but was unaffected by musical experience. Finally, a general asymmetry in sensitivity to mistuning was discovered, with compressed pitch differences being more easily detected than stretched ones.”

The results of this recent study shed new light on the contribution of beats and inharmonicity to people’s perception of dissonance when listening to out-of-tune instruments or voices. The researchers also found that a greater musical experience tended to improve people’s ability to use these two acoustic cues to detect mistuning.

The experimental methods employed by this research could soon be used to carry out additional studies focusing on the underpinnings of mistuning detection. Collectively, these research efforts could help to delineate the factors influencing how humans experience music and the extent to which it is perceived as enjoyable or unpleasant.

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