Sonification is the use of non-speech audio to convey information or perceptualize data. Auditory perception has advantages in temporal, amplitude, and frequency resolution that open possibilities as an alternative or complement to visualization techniques.
For example, the rate of clicking of a Geiger counter conveys the level of radiation in the immediate vicinity of the device.
Though many experiments with data sonification have been explored in forums such as the International Community for Auditory Display (ICAD), sonification faces many challenges to widespread use for presenting and analyzing data. It is difficult to provide adequate context for interpreting sonifications of data. Many sonification attempts are coded from scratch due to the lack of a flexible tool for sonification research and data exploration
The Geiger counter, invented in 1908, is one of the earliest and most successful applications of sonification. A Geiger counter has a tube of low-pressure gas; each particle detected produces a pulse of current when it ionizes the gas, producing an audio click. The original version was only capable of detecting alpha particles. In 1928, Geiger and Walther Müller (a PhD student of Geiger) improved the counter so that it could detect more types of ionizing radiation.
In 1913, Dr. Edmund Fournier d'Albe of Birmingham University invented the optophone, which used selenium photosensors to detect black print and convert it into an audible output. A blind reader could hold a book up to the device and hold an apparatus to the area she wanted to read. The optophone played a set group of notes: g c' d' e' g' b' c'' e''. Each note corresponded with a position on the optophone's reading area, and that note was silenced if black ink was sensed. Thus, the missing notes indicated the positions where black ink was on the page and could be used to read.
Pollack and Ficks published the first perceptual experiments on the transmission of information via auditory display in 1954. They experimented with combining sound dimensions such as timing, frequency, loudness, duration, and spacialization and found that they could get subjects to register changes in multiple dimensions at once. These experiments did not get into much more detail than that, since each dimension had only two possible values.
John M. Chambers, Max Mathews, and F.R. Moore at Bell Laboratories did the earliest work on auditory graphing in their "Auditory Data Inspection" technical memorandum in 1974. They augmented a scatterplot using sounds that varied along frequency, spectral content, and amplitude modulation dimensions to use in classification. They did not do any formal assessment of the effectivenes of these experiments.
In the 1980s, pulse oximeters came in to widespread use. Pulse oximeters can sonify oxygen concentration of blood by emitting higher pitches for higher concentrations. However, in practice this particular feature of pulse oximeters may not be widely utilized by medical professionals because of the risk of too many audio stimuli in medical environments.
In 1992, the International Community for Auditory Display (ICAD) was founded by Gregory Kramer as a forum for research on auditory display which includes data sonification. ICAD has since become a home for researchers from many different disciplines interested in the use of sound to convey information through its conference and peer-reviewed proceedings.
Some existing applications and projects
- auditory altimeter , also used in skydiving
- auditory thermometer 
- clocks with an audible tick every second, and with special chimes every 15 minutes
- cockpit auditory displays
- Geiger counter
- interactive sonification
- medical auditory displays
- multimodal (combined sense) displays to minimize visual overload and fatigue
- speed alarm in motor vehicles
- space physics 
- storm and weather sonification 
- volcanic activity detection
Many different components can be altered to change the user's perception of the sound, and in turn, their perception of the underlying information being portrayed. Often, an increase or decrease in some level in this information is indicated by an increase or decrease in pitch, amplitude or tempo, but could also be indicated by varying other less commonly used components. For example, a stock market price could be portrayed by rising pitch as the stock price rose, and lowering pitch as it fell. To allow the user to determine that more than one stock was being portrayed, different timbres or brightnesses might be used for the different stocks, or they may be played to the user from different points in space, for example, through different sides of their headphones.
Many studies have been undertaken to try to find the best techniques for various types of information to be presented, and as yet, no conclusive set of techniques to be used has been formulated. As the area of sonification is still considered to be in its infancy, current studies are working towards determining the best set of sound components to vary in different situations.
Several different techniques for rendering auditory data representations can be categorized:
- Parameter Mapping
- Model-Based Sonification
- Stream-Based Sonification 
- Acoustic Sonification 
- Kramer, Gregory, ed. (1994). Auditory Display: Sonification, Audification, and Auditory Interfaces. Santa Fe Institute Studies in the Sciences of Complexity. Proceedings Volume XVIII. Reading, MA: Addison-Wesley. ISBN 0-201-62603-9.
- Flowers, J. H. (2005), "Thirteen years of reflection on auditory graphing: Promises, pitfalls, and potential new directions", in Brazil, Eoin, Proceedings of the 11th International Conference on Auditory Display (ICAD2005): 406–409
- d'Albe, E. E. Fournier (May 1914), "On a Type-Reading Optophone", Proceedings of the Royal Society of London
- Pollack, I. and Ficks, L. (1954), "Information of elementary multidimensional auditory displays", Journal of the Acoustical Society of America
- Chambers, J. M. and Mathews, M. V. and Moore, F. R. (1974), "Auditory Data Inspection", Technical Memorandum 74-1214-20 (AT&T Bell Laboratories)
- Frysinger, S. P. (2005), "A brief history of auditory data representation to the 1980s", in Brazil, Eoin, Proceedings of the 11th International Conference on Auditory Display (ICAD2005) (Department of Computer Science and Information Systems, University of Limerick): 410–413
- Craven, R M and McIndoe, A K (1999), "Continuous auditory monitoring--how much information do we register?", British Journal of Anaesthesia 83 (5): 747–749, doi:10.1093/bja/83.5.747
- Kramer, G. and Walker, B.N. (2005), "Sound science: Marking ten international conferences on auditory display", ACM Transactions on Applied Perception (TAP) 2 (4): 383–388, CiteSeerX: 10.1.1.88.7945
- Thomas Hermann, Andy Hunt, and Sandra Pauletto. Interacting with Sonification Systems: Closing the Loop. Eighth International Conference on Information Visualisation (IV'04) : 879-884. Available: online. DOI= http://doi.ieeecomputersociety.org/10.1109/IV.2004.1320244.
- Thomas Hermann, and Andy Hunt. The Importance of Interaction in Sonification. Proceedings of ICAD Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6–9, 2004. Available: online
- Sandra Pauletto and Andy Hunt. A Toolkit for Interactive Sonification. Proceedings of ICAD Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6–9, 2004. Available: online.
- Barrass, S. and Best, G. (2008). Stream-based Sonification Diagrams. Proceedings of the 14th International Conference on Auditory Display, IRCAM Paris, 24-27 June 2008. online
- Barrass S. (2009) Developing the Practice and Theory of Stream-based Sonification. Scan Journal of Media Arts Culture, Macquarie University online
- Barrass S. (2012) Digital Fabrication of Acoustic Sonifications, Journal of the Audio Engineering Society, September 2012. online
- International Community for Auditory Display
- Sonification Report (1997) provides an introduction to the status of the field and current research agendas.
- The Sonification Handbook, an Open Access book that gives a comprehensive introductory presentation of the key research areas in sonification and auditory display.
- Using Sound to Extract Meaning from Complex Data, C. Scaletti and A. Craig, 1991.
- Auditory Information Design, PhD Thesis by Stephen Barrass 1998, User Centred Approach to Designing Sonifications.
- Mozzi : interactive sensor sonification on Arduino microprocessor.
- Preliminary report on design rationale, syntax, and semantics of LSL: A specification language for program auralization, D. Boardman and AP Mathur, 1993.
- A specification language for program auralization, D. Boardman, V. Khandelwal, and AP Mathur, 1994.
- Sonification tutorial
- SonEnvir general sonification environment
- Sonification.de provides information about Sonification and Auditory Display, links to interesting event and related projects
- Sonification for Exploratory Data Analysis, PhD Thesis by Thomas Hermann 2002, developing Model Based Sonfication.
- Sonification of Mobile and Wireless Communications
- Interactive Sonification a hub to news and upcoming events in the field of interactive sonification
- zero-th space-time association
- CodeSounding — an open source sonification framework which makes possible to hear how any existing Java program "sounds like", by assigning instruments and pitches to code statements (if, for, etc.) and playing them as they are executed at runtime. In this way the flowing of execution is played as a flow of music and its rhythm changes depending on user interaction.
- LYCAY, a Java library for sonification of Java source code
- WebMelody, a system for sonification of activity of web servers.
- Sonification of a Cantor set 
- Volcanoes may reveal secrets through 'song' (New Scientist)
- Sound of science (New Scientist) discusses many applications of sonification
- Sonification Sandbox v.3.0, a Java program to convert datasets to sounds, GT Sonification Lab, School of Psychology, Georgia Institute of Technology.
- Infrasound Laboratory of Hawaii (sounds)
- xSonify a Java application to display numerical data as sound, Goddard Space Flight Center, NASA
- Program Sonification using Java, an online chapter (with code) explaining how to implement sonification using speech synthesis, MIDI note generation, and audio clips.
- Earthquake Sonification using USGS XML feed and sound synthesis software, by Micah Frank
- New York City Taxi Real-Time Sonification using live video feeds from New York’s Traffic Management Center Max/MSP and Symbolic Sound's Kyma Software, by Micah Frank.