The highly worthwhile project to create an archive of sounds from across the UK, and to place these on a map, is interesting from several points of view. http://sounds.bl.uk/uksoundmap. Crowdsourced data collection is an exciting development. The sounds are interesting to browse and identify. The project also raises the question of how difficult it is to apply visually-oriented mapping practices to sound.
The differences between aural and visual media, sound and sight, the culture of the ear and that of the eye, are well documented. Sound is immediate, time-based, felt as much as thought about, and pertains to undifferentiation. As evident in the case of portable stereos, contemporary urban dwellers immerse themselves in sounds. By contract, vision invokes a sense of separateness, overview, the ability to lay things out as on a map. The spatial attributes of sound are fascinating and challenging, not least as we think of thresholds, zones of transition in our environment.
Acoustic thresholds are characterized by leakages and an even greater dynamism than the strictly formal and visual. In an essay on sounds in the city, Jean-Paul Thibaud calls on people to think of public spaces in terms of sonic “thresholds, knots and configurations.” The traveler with a personal stereo crosses a threshold when leaving the house, and encounters knots of concentration when negotiating the interface between ear, footstep, and built environment. Moving around the city involves the configuration of various “lived itineraries.” In their study of everyday sounds in the environment, Augoyard and Torgue explain sonic thresholds in terms of the cut, which: “is a sudden drop in intensity associated with an abrupt change in the spectral envelope of a sound or a modification of reverberation (moving from reverberant to dull spaces, for instance). This effect is an important process of articulation between spaces and locations; it punctuates movement from one ambience to another.”
Here a sound space is characterized as an ambience. The correspondences between visual and acoustic spaces are only loosely formed, and characterized as so many leakages across each other’s thresholds. In a journey along a street the walker experiences the sound of someone operating electrical equipment in a side street. The sound increases in intensity as she moves towards the side street and recedes as she continues on her journey. The sound is cut by buildings lining the streets in ways that views are not. Sound is subject to dissipation effects, reflections, and leakages. It also operates obliquely. You don’t need to face the side street to experience the sound. As with vision, the sound transitions can be abrupt, but unpredictable, and of unidentified source. Sounds can travel over and around obstructions. How therefore do we map sounds?
Reflections on Technology, Media & Culture 
While a picture is worth a thousand words, a sound is worth a thousand pictures – Murray Schafer
The sounds of an environment can be classified in to two major groups:
1- Static: Those sounds that are a part of the environment and rarely change or if they change they return to a state that is recognisable. These sounds might have variations depending on the time of the day and the climate (Eg: river flowing, frogs at night, morning bird song)
2- Dynamic/transient: These are sounds that are momentary and might not occur again (a bird flying over head, a boat down the river, a motor cycle passing by)
Both types of sounds can define the sound of a location.
IM Rawes at http://www.soundsurvey.org.uk/ has been creating sound maps of London over the past few years.
http://www.umapper.com/ is a service that allows the creation of sound maps. Although, it is a freemium service.
Alternatively, there is a service called Mapmaker (http://mapmaker.donkeymagic.co.uk/) which is free and can easily be integrated with flash audio players like the ones on SoundCloud.
More information is available here: http://www.soundsurvey.org.uk/index.php/survey/blog_comments/1326/
Sight may be the main sense that we use to perceive space, but sound is always an honest expression of reality. Therefore the auditory identity of the city can reveal its true character. Created from the merge of human voices with the elements of urban everyday life, it constantly changes, making every route in the urban fabric unique. Those routes can be regarded as ephemeral-liquid representations (maps) of the city puzzle.
The whole of these “audio” maps constitutes an instant experience of the urban life. Therefore, apart from how we can put sounds into a map, it would be interesting to see in which duration they are bound. The ephemeral nature of space in the terms of sound means that these sites could quickly change as they are a record of a specific moment. However, if these maps could be created in real time, they would be able to show the changes in the structure of space, revealing the urban trends which shape the city.
An effort to put sound into a map and create non-visual qualities of space was made by the greek participation in the Venice Biennale. The project was called “Athens by Sound” and tried to introduce the city of Athens to the visitors, through an interactive sonic map, which presented spaces of the city. The most important element was that the sounds were not the recorded, but were happening in real time, which gave the opportunity to experience liquid (live) sound.
Consequently, in my opinion even if we map sounds, there could not be a totally accurate one. Even as the map is being created, the constant change of actions and interactions in the urban environment will always make certain elements of the map obsolete.