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Over the past 20 years automobile quality, and consumer perceptions thereof, have been an increasing part of the vehicle engineering process. In automotive systems, torque-induced handwheel vibration is a significant source of consumer annoyance. When dealing with torque recordings containing a single or very small number of sinusoids, a time-referenced signal can easily be manipulated to yield instantaneous torque estimates. As the number of sinusoids (orders) grows, however, this becomes more difficult. In this paper, the authors demonstrate a simple technique to effectively estimate instantaneous torque level of high-order torque components when there are many higher-order sinusoids. The point is made that basic signal processing techniques applicable to time-referenced signals are also applicable to those referenced to angle or other variables.

A study was conducted to investigate the subjective responses to steering wheel vibration caused by the electric power steering. The objective was to correlate the subjective responses to a measurable parameter that can be used to assess various design alternatives. Evaluations of six steering wheel vibration levels were performed in a stationary vehicle. Two rating methods were used. Results showed a wide range of acceptability of steering wheel vibration over the conditions evaluated. RMS angular acceleration and peak to peak torque at the steering wheel shaft correlated best with subjective ratings.

Impulsive sound events (i.e. door closing) are often characterized as being undesirably sharp sounding. A high degree of perceived sharpness is normally related to large amounts of high frequency energy relative to the low frequency energy. In this project third octave data generated from a filterbank was used to calculate the center of gravity (cg) of the third octave bands. The result is the frequency corresponding to the centroid of the third octave data. Sounds with substantial high frequency energy have a centroid location that occurs at a higher frequency. The mean of the third octave cg over the duration of the transient event was investigated, in addition to sharpness as defined by Aures [1] and calculated on a commercially available analyzer. Correlation analyses to subjective data indicate that the mean third octave cg and the commercially available method produce comparable results for the vehicle closure sounds studied here.

The customer's perception of diesel sounds is receiving more attention since diesel engines are being used more frequently in recent years. This paper summarizes the results of a study investigating the sound quality of diesel idle sounds in eight vans and light trucks. Subjective evaluations were conducted both in the US and the UK so that a comparison could be made. Paired comparison of annoyance and semantic differential subjective evaluation techniques were used. Correlation analysis was applied to the subjective evaluation results to determine annoying characteristics. Subjective results indicated that most annoyance rankings were similar for both the US and UK participants, with some specific differences. Correlation of objective measures to annoyance indicated a high correlation to ISO 532B loudness, dBA and kurtosis in the 1.4 kHz to 4 kHz range (aimed at quantifying the impulsiveness perception).

This paper describes an investigation into the sound quality of passenger car and light truck closure sounds. The closure sound events that were studied included side doors, hoods, trunklids, sliding doors, tailgates, liftgates, and fuel filler doors. Binaural recordings were made of the closure sounds and presented to evaluators. Both paired comparison of preference and semantic differential techniques were used to subjectively quantify the sound quality of the acoustic events. Major psychoacoustic characteristics were identified, and objective measures were then derived that were correlated to the subjective evaluation results. Regression analysis was used to formulate models which can quantify customers perceptions of the sounds based on the objectively derived parameters. Many times it was found that the peak loudness level was a primary factor affecting the subjective impression of component quality.