The British Library's UK SoundMap offers some suggestions to help contributors get started, and these are couched in general terms because the choices people make will be informative.
Even so, someone setting out for the first time to record environmental sounds faces problems of choice more daunting than those confronting the novice photographer.
The photographer can look for ideas from the vast and unavoidable body of work compiled by other photographers, and in which popular themes can easily be detected. The most common tags on Flickr include staples such as 'sunset', 'winter', 'cat', 'flowers' and 'beach'.
In urban environments especially, visual means are used to broadcast information much more commonly than auditory ones. This discrepancy has likely increased over time as literacy has become more widespread and the background noise level of traffic has risen. Photographers have architecture, industrial design, fashion and advertising to draw upon.
Fortunately, a good stock of mental categories for sounds can make the recordist's life easier. Jean-Francois Augoyard's 2006 book Sonic Experience: A Guide to Everyday Sounds provides descriptions of over eighty everyday acoustic phenomena, including echo, vibrato and anticipation.
R. Murray Schafer's influential 1977 book The Tuning of the World contains a classification of 'sound objects' which is worth reproducing:
Human sounds: the voice; the body; and clothing.
Mechanical sounds: industrial and factory equipment; vehicles; aircraft; construction and demolition equipment; mechanical tools; ventilation and air-conditioning; and farm machinery.
Quiet and Silence
Sounds as Indicators: bells and gongs; horns and whistles; sounds of time; telephones; warning systems; signals of pleasure; and indicators of future occurrences.