There are certain clinical indicators of problems with the vocal cords, such as actual lesions or the simpler problem of day-to-day swelling. Singers and professional voice users may regularly perform the following daily screening routines to determine if there is a potential lesion on the vocal cords that warrants examination by a physician or if there is a swelling of the vocal cords that would prohibit singing or performing for that day. A good way to use these procedures is to initially screen yourself when your voice is at its baseline. Keep a record of the baseline measurements for later comparison. Any sudden or persistent variance from baseline measurements or from the norms may warrant medical attention.
1. Speaking Fundamental Frequency
Speaking fundamental frequency is the average pitch at which one speaks. Norms have been developed to determine average speaking pitch as influenced by a person's age and gender. A significant lowering of your average speaking fundamental frequency may indicate vocal fold pathology. In order to determine your speaking fundamental frequency:
- Say "mm-hmmm" several times
- Say "mm-hmmm" a last time and sustain the "mmm"
- Match the pitch of your "mmm" to a pitch played on well-tuned piano or other musical instrument
- Record the name of that matching pitch; this is your speaking fundamental frequency.
The following speaking fundamental frequency norms have been provided as a result of Dr. Daniel R. Boone's work published in 1991:
||Normal Speaking Pitch
||G below middle C
||C below middle C
||F below middle C
||A2 (8 notes below middle C)
2. Maximum Phonation Time
Maximum phonation time is a measurement of respiratory and sound control. Using a watch with a second hand, hold an "ah" for as long as you can and record the duration in number of seconds. Adults should typically be able to hold a quiet sound for 15 - 20 seconds; time significantly less than this may indicate vocal fold pathology (Boone, 1991).
3. Vocal Range
Vocal range describes the scope of sounds ranging from high pitches to low pitches that your voice can produce. Using a piano, identify the highest and lowest notes you can sing. You may use any vowel that is comfortable for you. Keep in mind that this does not necessarily indicate your functional singing range. The sounds may not be the most pleasurable to hear; however, these sounds identify how fast your vocal folds can potentially vibrate under normal conditions. In general, singers and healthy speakers should have between 18-24 whole notes in their vocal range; anything less may suggest vocal fold pathology.
4. Vocal Fold Efficiency or S:Z Ratio
Hold the hiss of a soft "ssss" sound for as long as you can on a single breath. Measure the duration in seconds. Repeat with a soft "zzzz" sound and compare the two durations. This measures how efficient the vocal mechanism is by comparing voiceless (open vocal folds) and voiced (closed vocal folds) sounds. Ideally, one should be able to hold each sound for an equal duration, indicating that the vocal folds are valving air effectively. Simply put, the ratio should be 1:1, meaning one should be able to hold both the /s/ and the /z/ for equal amounts of time. If the two durations are very different, this may be an indication of vocal fold pathology. For example, if a person could hold an /s/ for 20 seconds and a /z/ for 10 seconds, the vocal folds are inefficiently closing, wasting air.
5. Happy Birthday Task
Another practical measure of vocal health may be determined by singing "Happy Birthday" as quietly as possible in the upper third of your personal vocal range. First you must determine your full vocal range (see above). Divide your range into thirds, and locate the first note of the uppermost third of your range. Use this pitch as your starting pitch each time. If on a given day you cannot sing this tune without excessive breathiness, difficulty starting the sound, or voice "breaks," there is a good chance that vocal fold swelling may be present from overuse, acid reflux, abusive coughing, or a host of other causes of intermittent vocal fold swelling. Regardless of cause, vocal fold swelling indicates that it is not a good day to sing. When vocal fold swelling is indicated use judicious vocal rest (increasing silence with relaxed and gentle speaking only as necessary). Judicious vocal rest allows the troublesome swelling to subside (Bastian, Keidar, & Verdolini-Marston, 1990).