How can you complement objective NVH measurements with subjective evaluations?

1 Why subjective NVH evaluations are important

Objective NVH measurements can provide quantitative data on the frequency, amplitude, and duration of sound and vibration signals in a vehicle, but they cannot tell you how those signals are perceived by the human ear and body. Different people may have different sensitivities and preferences for NVH, depending on factors such as age, gender, culture, mood, and context. For example, some people may find low-frequency engine noise reassuring, while others may find it annoying. Some people may prefer a smooth and quiet ride, while others may enjoy some feedback and excitement from the road. Subjective NVH evaluations can help you understand how your target customers feel about the NVH of your vehicle, what aspects they like or dislike, and what improvements they suggest.

2 How to conduct subjective NVH evaluations

Subjective NVH evaluations involve collecting feedback from users or experts on the NVH of a vehicle, either in a real or simulated driving scenario. You can use different methods to collect subjective NVH feedback, such as surveys, interviews, focus groups, or ratings. Surveys are questionnaires that ask users to rate or rank the NVH of a vehicle or its components on a scale, such as 1 to 10, or to choose from a list of adjectives, such as loud, quiet, smooth, rough, etc. Interviews are one-on-one conversations that ask users to describe their NVH experience in more detail, such as what they heard, felt, liked, or disliked. Focus groups are group discussions that allow users to share and compare their NVH opinions with others. Ratings are numerical scores that are assigned by experts based on standardized criteria and guidelines for NVH quality.

3 What tools to use for subjective NVH evaluations

Subjective NVH evaluations require tools that can record, reproduce, and analyze the sound and vibration signals of a vehicle, as well as the user feedback. To conduct such evaluations, you can use sound level meters to monitor the overall loudness of the vehicle or its components, as well as the frequency spectrum and the sound quality. Additionally, microphones can help capture the sound waves of a sound source and convert them into electrical signals. Accelerometers measure acceleration or vibration of a moving object in meters per second squared (m/s2) or g-forces (g), which can be used to measure the vibration of the vehicle or its components, as well as the user feedback. Headphones and speakers deliver sound to and produce sound waves from electrical signals respectively. Finally, software programs can process, manipulate, and visualize the sound and vibration signals and user feedback to analyze and interpret subjective NVH data.

4 How to analyze and interpret subjective NVH data

Subjective NVH data can be analyzed and interpreted using various techniques and methods, depending on the type, format, and purpose of the data. Descriptive statistics provide numerical summaries that describe the basic features of the data, such as the mean, median, mode, standard deviation, range, and frequency. Inferential statistics test hypotheses and draw conclusions about the data by using t-tests, ANOVA, correlation, or regression. Qualitative analysis examines the meaning and content of the data through thematic analysis, content analysis, or discourse analysis. Visual representation displays the data in graphical or pictorial forms like bar charts, pie charts, scatter plots, or radar charts. All of these techniques can help you understand the central tendency, variability, and distribution of subjective NVH ratings or scores; compare different groups, variables, or conditions; identify themes and patterns; illustrate and communicate the data; and highlight similarities and differences among the data.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?