Comparison of the Perceived Intensity of Time-Varying Signals in the Tactile and Auditory Domain

Most natural signals vary with time. Impulsive sound and vibrations in cars are typical examples. The perceived intensity of such signals is time-dependent too. This study investigates the influence of the stimulus length of sinusoidal vibration bursts on the perceived intensity of seat vibrations. The resulting tactile vibration magnitude is discussed in comparison with the auditive loudness perception. An experiment was conducted, using vertical seat vibrations with frequencies of 40 Hz, 80 Hz, 160 Hz and 320 Hz. The length of the test stimuli varied between 40 ms and 3000 ms. The task of the participants was to adjust the intensity of the test vibration to the perceived magnitude of a reference vibration with the same frequency. A stimulus length of 1000 ms was chosen for the reference. The acceleration level of the reference vibration was set to 30 dB above the perception threshold. The results show a decrease of perceived vibration magnitude with decreasing burst duration if the stimulus is shorter than 320 ms. These data help to improve the modelling of tactile intensity perception. The final goal is to define a new perceptually motivated measurement for the perceived vibration magnitude M comparable to auditory loudness N.