Differences in listeners’ ratings

Dr. Bose is a psychoacoustician who works in a lab at a headphone company. One of her jobs is to assess new headphone designs and to determine listener preferences. She compared three new headphones that used new noise reduction algorithms (NR1, NR2, & NR3) to a headphone that used the company’s current noise reduction algorithm (Current). 32 participants were randomly assigned to one of the four listening conditions. Participants listened to 30 1-minute samples of music from assorted genres and rated the reproduction quality of each sample using a 9-point rating scale (1=poor quality sound; 9=excellent sound). The mean ratings are shown on the right. Did Dr. Bose find any differences in listeners’ ratings of music quality among the different noise reduction algorithms?