Valid psychoacoustic listening tests require blind conditions and carefully worded tasks.

Evidence

In any case, it is important to eliminate all sources of error and bias in psychoacoustic tests. The ideal situation is a blind test, where subjects have as little information as possible on the sounds they are hearing. The wording of the questions or tasks is very important in this respect. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 907