A listening experiment identical to that described in the previous section was performed with four graduate students studying violin at New England Conservatory and a professional violinist from the Boston area, the goal being to determine whether string players perceive vibrato produced by stringed instruments in the same way as other musicians do. One of the graduate students professed to have absolute pitch, but his results did not differ from the others, so they are included.
The results on the individual subjects are found in Table 4. Their average psychometric curve is in Figure 8, and the corresponding curve for the data transformed using the logistic transformation is found in Figure 9. A statistical analysis performed on the transformed data indicated significance only for target pitch level. All other p values were greater than .08.
As was found for the MIT listeners, the data support the conclusion that the pitch center of the vibrato is at its mean. The psychometric curve is steeper around pitch level 0 indicating that these subjects are a little better at pitch discrimination than the MIT listeners. Alternatively this could be due to the fact that the sounds were produced by a stringed instrument, and these listeners had had far more experience judging intonation of these particular sounds.