I've been involved in this type of work and the whole point is that the human perception & preference systems have cross-talk that literally makes it impossible to completely separate out your response to any single object.
Thus, some of the positivity created by the visual appearance is mistakenly attributed to the sound. The only way to completely prevent that is to listen blind. Of course you're still going to be biased in your evaluations by all the other positive and negative experiences that are co-occuring with the listening experience. The brain is simply not able to fully separate out the unique influence of any one variable. You can do things to improve accuracy, but there's just too much going on for the system to be perfect.
Just like in music reproduction, everything matters.
P.S. The antidotes and comparisons listed above, while relevant, are not really informative. You would need to hear the exact same item and perceive it as visually beautiful in one condition, but visually hideous in the other.
Thus, some of the positivity created by the visual appearance is mistakenly attributed to the sound. The only way to completely prevent that is to listen blind. Of course you're still going to be biased in your evaluations by all the other positive and negative experiences that are co-occuring with the listening experience. The brain is simply not able to fully separate out the unique influence of any one variable. You can do things to improve accuracy, but there's just too much going on for the system to be perfect.
Just like in music reproduction, everything matters.
P.S. The antidotes and comparisons listed above, while relevant, are not really informative. You would need to hear the exact same item and perceive it as visually beautiful in one condition, but visually hideous in the other.