Audio tour

An audio tour or audio guide provides a recorded spoken commentary, normally through a handheld device, to a visitor attraction such as a museum. They are also available for self-guided tours of outdoor locations, or as a part of an organised tour. It provides background, context, and information on the things being viewed. Audio guides are often in multilingual versions and can be made available in different ways. Some of the more elaborate tours may include original music and interviews. Traditionally rented on the spot, more recently downloaded from the Internet or available via the mobile phone network. Some audio guides are free or included in the entrance fee, others have to be purchased separately.
History.
Willem Sandberg, director of the Stedelijk Museum in Amsterdam from 1945 to 1962, pioneered the world's first museum audio tours. When invented in 1952, the developers were drawn by its unique potential to mediate an experience individually controllable by each visitor, which was content-rich, was personal to them, was available at any time, and suited learning styles not served by catalog, text panel, or label.
Sandberg's ambulatory lectures were delivered through a closed-circuit shortwave radio broadcasting system in which the amplified audio output of an analog playback tape recorder served as a broadcast station, and transmission was via a loop aerial fixed around the gallery or galleries. Identical lectures in Dutch, French, English, and German were recorded onto magnetic tapes, broadcast in turn through the aerial, and picked up by visitors through a portable radio receiver with headphones, when inside the loop.
The system was such that all visitors with a receiver could only hear a specific piece of commentary at any time; hence, groups of visitors would move through the galleries and look at exhibits as if guided by an invisible force, in complete synchronicity.
Electronic multimedia guides.
A multimedia electronic guide is a device specially designed to provide audio, visual or textual content to museum visitors with or without user interaction. It may also provide alternative content corresponding to different personal preferences. It may include accessories such as headphones, a digital pen and displays with LEDs or LCD screens.
These smart guides may be operated to supply content in different languages and accents, with different voice alternatives, with text, and with age group specific content. They can be operated in several ways:
These electronic guides can provide the museum management with useful statistics and reports, which may include tour statistics, visitor statistics, opinions, and other surveys.
Cell phone tours.
A cell phone tour is an audio tour where pre-recorded or stream audio interpretation for a heritage site or a cultural exhibit is provided via a cell phone. Cell phone audio tours have the advantage that most visitors already have the equipment needed to take the audio tour, being their cell phones.
Each venue is assigned a phone number with appropriate stop numbers, displayed next to the exhibit. Once a visitor has dialed in, they will be prompted and can enter the corresponding stop number of the exhibit they’re viewing, to hear the recorded content. These tours also enable the visitors to: fast forward, rewind, pause, as well as leave a feedback message for each exhibit or the whole tour; simply by pressing a number. In addition to audio content, some providers are also able to stream video, and text message recent visitors with updates. This is the old-style approach, not used widely.
Smartphone tours.
Smartphones have significant advantages over cell phones, as they have story-triggering technologies (GPS, bluetooth, NFC, QR-code scanner) and can use the power of mobile apps to deliver the right story in the right language in the right place and in the right context (e.g. the evening tour, or a winter tour). Stories could be adjusted to the pace and mood of the user. Of course, such guided tours will use other types of content, above audio: photo, texts, video, quests. Such apps can work online and offline.
Smartphone tours could guide the user outdoor (streets, highways, zoos, parks, archaeological sites) and indoor (museums), using different guiding techniques.
There are many apps available on the market, developed by cities, museums and private companies:
Examples (individual guides): 
Platform solutions.
Like it happens with any other type of content (e.g., YouTube in video), development of smartphone guiding apps inevitably led to the launch of so-called "platforms", which aggregate thousands of tours and stories:
Those platforms often come with the disadvantage of varied quality and missing update responsibility for individual tours. Some offer free tours while others rely on paid audio guides. However, there are also many beneficial changes due to the existence of audio guide platforms: