Cold water and your voice
The hypothesis holds true: the singers were less able to hit high pitched notes after drinking cold water.
For a singer to keep his/her vocal cords healthy, he should drink an ample amount of lukewarm water in order to ensure that there is minimal build up of mucus in his/her throat. He should not consume too much of dairy products. He should also not drink alcohol or smoke. Lastly, he should avoid caffeinated drinks such as coffee and tea..
Get the singers to consume dairy products for a week. Then, conduct the experiment.
Use children of different ages and genders. How do their results compare?
Vocal health, voice care, food & drink dos & don'ts, singing techniques, free voice analysis software: http://www.consumingexperience.com/2007/07/vocal-health-voice-care-food-drink-dos.html
Singer’s vocal health tips - http://www.starsinginglessons.com/vocal-health-tips.php