The intensity of auditory warning tones in the automobile environment: detection and preference evaluations

Psychophysical evaluation of auditory signals in passenger vehicles

Twenty-one experienced drivers were recruited for the evaluation of sounds of four functions (horn, indicator, door open warning, and parking sensor) made by 11 car brand names. Each participant was required to evaluate all of the above sound signals by a pair-comparison test. After the comparison test, each participant was shown his/her pair-comparison result and was asked to comment on their preference and appropriateness of a sound. The physical properties and interview data were compared and summarized to propose design recommendations. Our results indicate that complex tones and a fundamental frequency around 450 Hz were most preferred for horns while for indicators the preferred sounds had a higher dominant frequency [corrected].To reduce monotony, the indicators with double clicks and an OFF time interval of between 330 and 400 ms between two clicks were most preferred. Regarding door warning sounds, the waveform starting with a higher intensity then fading towards zero intensity is most preferred while for parking sensors, sounds beginning with a longer OFF time (about 500 ms) and having 3 or 4 distinctive tempo variations were most preferred. The relationship between pleasurability and pitch, loudness, and the tempo of sound signals basically followed an inverted-U function. Sound designers should avoid using very extreme parameter values when generating sound for a given function.

Auditory Displays for In-Vehicle Technologies

Modern vehicle cockpits have begun to incorporate a number of information-rich techno-logies, including systems to enhance and improve driving and navigation performance and also driving-irrelevant information systems. The visually intensive nature of the driving task requires these systems to adopt primarily nonvisual means of information display, and the auditory modality represents an obvious alternative to vision for interacting with in-vehicle technologies (IVTs). Although the literature on auditory displays has grown tremendously in recent decades, to date, few guidelines or recommendations exist to aid in the design of effective auditory displays for IVTs. This chapter provides an overview of the current state of research and practice with auditory displays for IVTs. The role of basic auditory capabilities and limitations as they relate to in-vehicle auditory display design are discussed. Extant systems and prototypes are reviewed, and when possible, design recommendations are made. Finally, research needs and an iterative design process to meet those needs are discussed.