Human Perception of Piano Timbre Variations Relative to the Piano's Dynamic Range

Abstract

The purpose of this study was to investigate the perception of brightness as it relates to loudness variations in piano tone. A single note was recorded with multiple intensities and used as the stimuli. I normalized all recorded notes to be perceived with the same volume and with the same duration. Consequently, the tone quality could be evaluated without the influence of loudness. Professional musicians and music students were invited to participate. I designed a mechanical apparatus, which produced a measured amount of force applied to the piano key. This device was used to record an intensity range of approximately 23 dB Sound Pressure Level (SPL) from a single key in a Yamaha C2 grand piano. Subjects listened to recordings arranged two by two, and then chose the brightest tone of the pair. The study found that participants easily matched (over 90%) a louder sound to a brighter tone when listening to dynamic ranges larger than 4.9 dB SPL. Participants had more difficulty in choosing the brightest tones from pairs with smaller differences in dynamics (73.8% of correct matching when listening to changes of only 1.73 dB SPL). The smallest differences in intensity levels produced results indicating the crossing of a threshold in the perception of brightness. In psychophysics, this threshold is called the just noticeable difference (JND) and it is defined as the smallest intensity variation that subjects can perceive 50% of the time.