The past decade has seen significantly increasing interest in the development of systems based on acoustic sensors for the localization, tracking and identification of moving objects. Acoustic sensors are capable of performing functions normally associated with traditional volumetric radar, based on the emission of electromagnetic waves. Acoustic systems have the undeniable advantage of totally passive function for detection, without any emissions from the sensor, based only on analysis of the spectrum of acoustic emissions from the objects in the environment.

Just as in radar technologies, acoustic volumetric systems detect not only the sound wave emitted by a particular source, but also the the sound waves reflected from the surrounding environment. It is thus possible to build acoustic ‘maps’ of the monitored space, isolating only the information of interest.

Use of acoustic sensors in automotive applications

Acoustic technologies clearly offer opportunities for important improvements in the automotive sector, where high-end cars already use electromagnetic radar for collision avoidance devices. The much lower cost of acoustic systems could allow installations in all or almost all categories of cars.

The technological basis of acoustic systems consists of matrices of microphone arranged in planned, controlled configurations, developed for the specific application, applying phased array methodologies similar to those of traditional radar.

In addition to the array, the main modules composing the product are:

  • A mechanical support for the antenna, allowing the movement of the arrays to achieve continuous operation;
  • A data acquisition and processing unit, both hardware and software, developed for the specific application;
  • A data presentation console, with control software, again customised for the particular scenario.

The SAUND4 project has focused on research and design of technological solutions for the automotive sector:

  • Development of a vehicle-installed system for on-board diagnostics;
  • Develop a driver-assistance anti-collision system;
  • Develop a microphone array for generation of acoustic mapping, capable of detecting mechanical defects.


The use of acoustic sensors in automotive applications presents numerous scientific and applied technical challenges.



High technological content
Low cost
Advanced computer algorithms for tracking and classifying acoustic sources

Application scenarios

Monitoring the correct function of the vehicle engine and mechanical components, with verification of the status of the observed components on the basis of the sounds they produce.
Driver assistance
Assisting the driver of the vehicle by acoustically monitoring the zones hidden from normal vision or unavailable by rear-view mirrors, for identification of the obstacles they contain.
Monitoring an area of interest by detection of acoustic sources, using a microphone array for their localization, tracking and classification, and then providing an acoustic map of the area under observation.