Click here to purchase the entire book in PDF format. Types of subjects You will have to know when you use a person as a subject in a listening test what kind of listener they are. There are four basic categories that you can put people into when you're doing this. Naive - A naive subject is someone who has never participated in a listening test, doesn't listen to things for a living (like a recording engineer or a musician, for example) but who might have some previous knowledge (right or wrong) about audio. For example, someone who read up on what kind of stereo to buy 5 years ago, and who regularly listens to pop tunes in the car, but is an accountant and really doesn't worry too much about the crappy quality of MP3's could be considered a naive listener. Experienced - An experienced subject is someone who listens to audio regularly, but is probably not trained in detecting or evaluating the particular attributes that you're interested in. For example, a violinist in a stereo imaging test would be considered an experienced listener. Such a person has prior training in concentrating on how something sounds, but is not necessarily trained in concentrating on the aspect of sound that you're testing. Expert - An expert subject is someone who has received a great deal of training in hearing the attributes that you're researching. For example, a full-time recording engineer working for a classical recording label could be considered an expert in evaluation of microphone distortion characteristics. Trained - A trained subject is a person who has been specifically trained in listening for the particular attribute you're investigating. For example, if you take a naive subject, and teach them how to detect artifacts caused by MP3 data reduction using various recordings, then use that person to test the detectability of MP3 artifacts for other recordings and other bitrates, then you have a trained subject.