Berkeley team explores sound for indoor localization

Aug 01, 2014 by Nancy Owano weblog
Credit: arXiv:1407.4409 [cs.HC]

The global positioning system, or GPS, has its limitations—namely, it cannot work indoors. Potential solutions for indoor positioning continue to fire up the imaginations of scientists. The latest news involves a form of echolocation. MIT Technology Review reported on the approach for indoor localization based on sound. Ruoxi Jia and team at the University of California, Berkeley developed a simple, cheap mechanism, said Technology Review, that can identify rooms based on a relatively small dataset. Their paper describing their system was submitted on July 16 to the arXiv server; authors are Ruoxi Jia, Ming Jin, and Costas J. Spanos of the University of California, Berkeley. They call their system SoundLoc. In their paper, "SoundLoc: Acoustic Method for Indoor Localization without Infrastructure," they described SoundLoc as "a room-level localization system that exploits the intrinsic acoustic properties of individual rooms." Their SoundLoc method is based on the extraction of acoustic features of rooms. The team said they can acquire RIRs [room impulse responses]by using built-in speakers and microphones on laptops.

Also, a "noise adaptive reverberation extraction algorithm" was developed for feature extraction from the noisy RIRs. How it works: "Emit a sound and then listen for the return which will be distorted in a way that depends on the size and shape of the , the materials on the walls and floors as well as the furniture and people within it," said Technology Review.

The researchers tested their system in ten rooms on the Berkeley campus. Data was taken using the built-in microphone and speakers on an ordinary laptop. "The laptop produces a set of sound waves and then listens for the echo. They took 50 samples at each location, which included background noise such as footsteps, talking and heating and ventilation sounds. They processed this data to find the echo fingerprint for each room," said Technology Review. -

The team said there was a 97.8 percent accuracy in identifying the individual rooms. They wrote, "The acoustic features we extracted are shown to be distinctive, robust and efficient to compute. 97.8% of overall accuracy has been achieved for 10 rooms' identification."

Of what use is their research? MIT Technology Review commented how "Jia and co are particularly interested in using the technique to reduce the energy consumption in buildings. Some 40% of energy usage in the US comes from commercial and residential buildings. If those buildings are empty, then that represents a significant waste."

The authors said in their paper that "Identifying locations of occupants is beneficial to energy management in buildings. A key observation in indoor environment is that distinct functional areas are typically controlled by separate HVAC and lighting systems and room level localization is sufficient to provide a powerful tool for energy usage reduction by occupancy-based actuation of the building facilities."

Explore further: Indoor mapping iOS solution bypasses Wi-Fi, Bluetooth beacons (w/ Video)

More information: SoundLoc: Acoustic Method for Indoor Localization without Infrastructure, arXiv:1407.4409 [cs.HC] arxiv.org/abs/1407.4409

Abstract
Identifying locations of occupants is beneficial to energy management in buildings. A key observation in indoor environment is that distinct functional areas are typically controlled by separate HVAC and lighting systems and room level localization is sufficient to provide a powerful tool for energy usage reduction by occupancy-based actuation of the building facilities. Based upon this observation, this paper focuses on identifying the room where a person or a mobile device is physically present. Existing room localization methods, however, require special infrastructure to annotate rooms.
SoundLoc is a room-level localization system that exploits the intrinsic acoustic properties of individual rooms and obviates the needs for infrastructures. As we show in the study, rooms' acoustic properties can be characterized by Room Impulse Response (RIR). Nevertheless, obtaining precise RIRs is a time-consuming and expensive process. The main contributions of our work are the following. First, a cost-effective RIR measurement system is implemented and the Noise Adaptive Extraction of Reverberation (NAER) algorithm is developed to estimate room acoustic parameters in noisy conditions. Second, a comprehensive physical and statistical analysis of features extracted from RIRs is performed. Also, SoundLoc is evaluated using the dataset consisting of ten (10) different rooms. The overall accuracy of 97.8% achieved demonstrates the potential to be integrated into automatic mapping of building space.

add to favorites email to friend print save as pdf

Related Stories

One-way transmission system for sound waves

Jul 26, 2011

While many hotel rooms, recording studios, and even some homes are built with materials to help absorb or reflect sound, mechanisms to truly control the direction of sound waves are still in their infancy. ...

A layer of cool, healthy air

Dec 17, 2012

Stratum ventilation systems have been touted as a much more energy efficient system for cooling buildings such as school rooms and offices in hotter climes based on the provisions of the recent ANSI/ASHRAE 55-2010. They may ...

Comfortable climate indoors with porous glass

Jul 31, 2014

Proper humidity and temperature play a key role in indoor climate. In the future, establishing a comfortable indoor environment may rely on porous glass incorporated into plaster, as this regulates moisture ...

Making GPS-like localization work indoors

Jun 26, 2012

You’re in a hurry. You’ve rushed to the nearest shopping mall during your lunch hour, looking for one item, one item only. It’s a five-minute task, except for finding the store with the right item—and ...

Recommended for you

Coping with floods—of water and data

Dec 19, 2014

Halloween 2013 brought real terror to an Austin, Texas, neighborhood, when a flash flood killed four residents and damaged roughly 1,200 homes. Following torrential rains, Onion Creek swept over its banks and inundated the ...

Cloud computing helps make sense of cloud forests

Dec 17, 2014

The forests that surround Campos do Jordao are among the foggiest places on Earth. With a canopy shrouded in mist much of time, these are the renowned cloud forests of the Brazilian state of São Paulo. It is here that researchers ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.