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My Research

Research Problem

From the early 21st century there has been a rapid increase in the production and sale of electric and hybrid vehicles (H/EVs). These vehicles have advantages over combustion engine vehicles like higher fuel efficiency, less air pollution and a smoother driving experience.
These vehicles produce much lower interior and exterior noise compared to combustion engine vehicles. As a result, H/EVs are usually 'too quiet' to be detected using sounds at low speeds (usually below 20 kph). Therefore, they may pose a threat to the safe travelling of pedestrians, cyclists, runners, and other road users.
New legislation states that H/EVs should emit 'non-vehicle based sounds' using devices such as speakers fitted to the vehicle.
These sounds should alert pedestrians to the vehicles’ presence. Additionally, H/EV manufacturers want these sounds to reinforce the impression of the vehicle brand.
pedestrians electric vehicle too quiet to be detected 
A challenge for the NVH experts is to come up with appropriate methods for evaluating the exterior sounds of H/EVs so that they comply with the legislation to ensure pedestrians' safety and reinforce the vehicle brand (as desired by the vehicle manufacturer).

Research Methodology

Research question:
How do we evaluate future electric vehicle sounds?
Research objectives:
  1. Formulate a methodology for evaluating EV sounds by critically reviewing the academic literature, vehicle legislation, and manufacturer’s requirements.
  2. Test, validate and improve the proposed methodology

Research procedure:
The research framework involves communicating and using information from three sources namely: the literature on evaluation of automotive sounds, the legislation governing the non-vehicle based EV sounds, and the H/EV manufacturers’ requirements and expectations from these sounds. Refer to the figure below:
Based on this, the major challenges of the non-vehicle based EV sounds are:
  • ensuring pedestrians’ safety (being appropriately detectable and complying with the legislators) and,
  • reinforcing the brand image (as desired by the manufacturer)

A methodology was proposed to holistically evaluate EV exterior sounds for the criteria of pedestrians’ safety and brand reinforcement, by suggesting an experimental approach that assesses − detectability of these sounds and emotional evaluation of the vehicle based on listening to its sounds.

An initial methodology, constituting experimental guidelines for evaluating EV exterior sounds, was formulated by critically reviewing the knowledge base (literature, legistaion and manufacturers). An iterative process tested and further improved the developed methodology using evaluation experiments. Refer to the flowchart below:


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