There are absolutely "studies" that found increase in plant growth from different types of music. Unfortunately, many of them are sooo shoddy in a scientific sense that the results are meaningless.
I just read one paper by two Indian grad students (lame ones at that) where there study looked at 5 groups of 4 plants. I'm sorry, but a sample size of 4 is not large enough to show a trend. The also "forgot" to actually complete a statistical analysis and generate a P value to actually demonstrate a positive correlation between music and growth.
As a guy with a BS in wildlife science (which is a shit load of statistics) and a MS in ecology, I can tell you that many of these "studies" are garbage at best.
Go look at your 30 or 40 plants in your veg area. I guarantee there is a differnece in total plant height between them... it's called natural variability (and lack of environmental control). But, as MANY a weed grower has done before you, feel free to chalk it up to any one condition.
Let's just say this, there are many more areas that deserve far more of your attention in terms of boosting growth and yield then playing music.