Having visited quite a few tourist attractions offering audio guides, the differences in what is available is extensive. From Hop on Hop Off tours where you plug in the headphones, through to hand held devices similar to a smart phone. There are devices that provide a monologue that plays from start to finish as well as ones that allow you to hear additional information about key areas of interest.
There are guides you hang around your neck and listen to. It can be distracting with these when in large groups, hearing multiple versions of the commentary. In some instances, you have to walk around holding it to your ear to hear. This makes it difficult to take photos at the same time. In some cases you can pause the commentary, but in others, you had to miss the section that was playing whilst taking the photo. In one instance (Royal Yatch Brittania), the guide included a large handle, so the device was about 25 cm long, this made it easy to hold, but reminded me of the early mobile phones.
One of the problems I have experienced is the difficulty in fast forwarding or skipping through sections that you didn’t want to listen to.