Voice Production and Voice Care
To coincide with World Voice Day 2007 (April 16th) the BVA has published information and guidelines concerning Voice Production & Voice Care. (Written by Sara Harris, Specialist Speech and Language Therapist and Team member, The Voice Clinic, London).
What do we mean by 'Voice'?
Image right: The larynx open
'Voice' is the sound we generate to make information audible. The information may be speech, song or emotional sounds, such as laughter or sobs. The vocal folds (traditionally known as the vocal cords) are two folds of tissue protruding from the side walls of the airway. The two folds contain a ligament and muscle and are covered with a mucous membrane. They are attached into the Thyroid cartilage (Adam’s apple) anteriorly (at the front) and the arytenoid cartilages posteriorly (at the back). The vocal folds and the cartilages that protect them are known as the larynx. During breathing the vocal folds remain apart, leaving an open “V” shaped airway to the lungs. During voicing they come together closing the airway completely. During expiration (breathing out) a strong flow of air coming from the lungs, meets the restriction made by the closed vocal folds. The pressure of the air begins to build and when it reaches a certain level it overcomes the resistance created by the closed vocal folds and a brief pulse of air is released. As the immediate pressure drops the vocal folds close once more and the cycle begins again. The pulses of air that are released produce the vibrations we hear as sound. They are picked up by the listener’s ears and their meaning interpreted by the listener’s brain.
Resonance and articulation
Image right: The larynx closed
Above the vocal folds the airway opens out into the pharynx (back of the throat), mouth and nose. The shape and length of this part of the airway can be manipulated by various muscle groups to enhance or “resonate” certain pitches. It acts rather as the sounding board does on a guitar or violin, only unlike the guitar or violin, it is not fixed and can change flexibly to amplify the wide variety of sounds produced by the human voice. Movements of the tongue and soft palate shape the voice into the distinctive sounds we recognize as the vowels and consonants of speech.
Each person can produce a wide range of different pitches between their lowest note and their highest. We use this ability to change pitch for intonation during speech and for singing. Intonation gives valuable information about the meaning of the spoken words. In English for example, a rising pitch frequently indicates a question, and a falling tone indicates that that the speaker has finished speaking. We also use pitch change to convey emotion, for example the high pitches of screams or the low growls that threaten aggression. We change pitch vocally in a similar manner to the way in which we change pitch on a stringed musical instrument. High notes are produced by stretching and thinning our vocal folds and low notes by shortening and thickening them.
We can also change the quality of our voices to convey emotion and to suit our situation. Human Beings are extremely good at recognizing the emotional content of speech from these changes in vocal quality. Angry voices, for example, may be described as harsh, strident, hard edged or tight while fearful voices may be tremulous, strangled or weak. Sad voices are often monotonous, breathy and lacking energy.
What changes when we have a voice problem?
Image right: Nodules on the larynx
Anything growing on or in a vocal fold or anything that alters their straight edges will interfere with the sound of the voice, so that it will be perceived as hoarse/husky. Swelling associated with inflammation and laryngitis makes the vocal fold thicker, heavier and stiffer. The vocal pitch will lower because the folds are thicker and the increased stiffness causes irregular and inconsistent vocal vibrations. Perceptually the voice will be heard as rough and breathy in quality. Sometimes the folds can become so stiff (as with a cancer) they frequently fail to vibrate at all causing the voice to cut out intermittently. Irregular areas of stiffness along the edges of the vocal folds may also interfere with the pitch, causing sudden breaks into falsetto or two different pitches to be heard at the same time (diplophonia).
Image right: Reinke's oedema
Occasionally, the nerves that control the opening and closing of the vocal folds can be damaged by a virus, pressure or injury so that one (or both) folds are paralyzed. When this happens the vocal folds can no longer close completely. Air escapes audibly, giving a weak and breathy quality to the voice. The affected vocal fold is no longer able to shorten and thicken effectively in order to produce the low notes we need for our speaking voices, and characteristic breaks into falsetto and diplophonia (described above) will be heard. Several other neurological problems can cause voice changes, for example Parkinson’s’ disease and some types of stroke. One condition, known as spasmodic dysphonia, can make the voice sound tight and strangled.
The larynx may suffer external trauma from sports injuries, physical attacks or from seatbelt compression in car accidents. Sometimes the way in which the voice is used may damage the vocal folds. Shouting and screaming or violent coughing for long periods may cause irritation, swelling and occasionally bleeding into the vocal fold. Certain medications may irritate the vocal folds either directly, (e.g. some asthma inhalers), or indirectly by causing coughing and /or dryness (e.g. some blood pressure medications).
Image right: Palsy
Voice problems can also develop even when both vocal folds are healthy and move fully. Conditions affecting the lungs, such as asthma or emphysema, may reduce the power of the airflow so that the voice cannot be efficiently initiated. Changes in the balance of muscle tone between the different muscles groups in the larynx can affect the initiation and maintenance of voicing. It can also precipitate variations in vocal fold closure, which in turn, can alter voice quality, vocal comfort and the stamina of the voice.
Occasionally, emotional states caused by life stresses can change our usual ability to control voice production. In its most severe form the voice can be lost completely reducing the sufferer to a whisper or virtually no sound at all. Unfortunately, the emotional nature of the voice loss is usually unconscious, which makes it very difficult for the sufferer to understand why the vocal folds are described as healthy and normal by the examining doctor, but he/she is unable to produce a voice.
What symptoms should I look out for?
ANY change in voice quality (hoarseness, roughness, and breathiness), any pain or discomfort that develops during speaking or singing, and any vocal fatigue, (where the voice tires and fades), that fails to resolve after two weeks should be reported to your GP and investigated.
Where should I seek help?
Initially, report you symptoms to your GP. It is important to tell him/her if you smoke and drink alcohol, if you are regularly exposed to atmospheric pollutants and if you have noticed any other changes in your health (for example, a cough, swallowing difficulty, throat/ vocal pain, or acid indigestion). Your GP can treat many of the health problems that are associated with voice disorders. They can also arrange investigations such as blood tests or X-rays that will help diagnose your voice problem and they can refer you on to an Ear Nose and Throat specialist or Voice Clinic for examination of your vocal folds.
The GP will usually refer you to the ENT specialist so that you can be examined to ensure that you have not developed any serious disease, such as a cancer. Some GPs are able to refer straight to a Multidisciplinary Voice Clinic. These are specialist clinics where several professions specializing in voice will assess your voice problem. The core Voice Clinic team will be the ENT surgeon, who will examine your voice and make the medical diagnosis, and the Speech Therapist, who will examine the way in which you produce you voice. However other specialists may also be present, for example, a voice specialized osteopath or physiotherapist, a singing advisor or a psychologist, depending on the clinic you visit.
In addition to examining the vocal folds, the ENT surgeon will be able to arrange further diagnostic tests, for example, an examination of the vocal folds under anaesthetic. A small sample of tissue can then be removed and examined under the microscope to determine the nature of any visible changes on the vocal folds (e.g., growths or swelling). This procedure is known as a biopsy. Other supporting tests may be necessary, such as scans, blood tests or X-rays. The ENT surgeon can also provide surgery to remove diseased or damaged vocal tissue or arrange for appropriate medication. If the voice problem is related to other medical problems the ENT surgeon may refer on to another specialty, such as a neurologist or a gastroenterologist. If the voice problem is related to the way in which the voice is used the Speech Therapist, Singing Advisor or Physiotherapist/Osteopath may provide a course of therapy. Your progress will usually be monitored during your treatment to make sure your voice recovers fully.
What can I do to avoid voice problems?
There a many things you can do to help prevent voice problems developing. Healthy voices respond well to the following:
REST: if you have a throat infection or laryngitis rest your voice and don’t speak more than you have to. A day off work when an infection is acute may well save a week off later on when the laryngitis has become chronic, especially if you have a vocally demanding job.
STEAM: Steam inhalations are very soothing for voices, especially when you have laryngitis or have strained your voice. Your nose and chest like steam too so coughs, blocked noses and inflamed sinuses respond as well. Steam reduces swelling and vocal irritation very effectively. You do not need to add anything in the water and if you do not wish to sit with a towel over your head over a bowl of steaming water a steamy bath, shower or the steam room at the local gym will work just as well.
WATER: Drink plenty of water. 6 to 8 large glasses of water a day are usually recommended. The thin mucus that lubricates your vocal folds (and your nose, throat and chest) depends on the water content of the body. Without plenty of water it becomes thick and sticky. The vocal folds may become dryer and stiffer making them more vulnerable to damage through excessive or inefficient voice use. The sticky mucus can also cause irritation leading to coughing or throat clearing which may further damage the vocal folds. Coffee and tea tend to be have a diuretic effect causing fluid loss through increased urination so are best kept to a minimum.
GOOD POSTURE: Efficient voice production is helped by keeping good posture, especially when using the telephone or working on key boards for long periods. Poor posture can distort your neck/back alignment affecting the resonating spaces in the throat and the control of the laryngeal muscles. It can also affect your breathing patterns reducing breath control and putting strain on the voice.
BREATHING: Take regular exercise to keep your breathing good and your muscles relaxed and supple. Try not to speak while out of breath or speak too long on one breath as too little air can put a strain your voice. If you are breathless or have difficulties with breathing consult your doctor to find out why and what you can do about it.
RELAXATION: Tension in any part of the body tends to generalize and may affect the larynx. Tight tense muscles do not work as efficiently as relaxed muscles producing fatigue and discomfort. Jaw, neck and shoulder exercises can help keep the voice relaxed and classes in such things as Yoga, Tai Chi, Pilates or Alexander Technique can be very helpful for general fitness, relaxation and improvements in breathing and posture
VOCAL WARM UPS: The voice is like the rest of the body, it likes to be warmed up before exercise to prevent injury. A useful selection of exercises can be found on the Voice Care Network website (www.voicecare.org.uk) or by following the World Voice Day link to the American website.
VOCAL WARM DOWNS: It is also important to warm the voice down after it has been used heavily, especially after singing or use against noise. Increasing vocal volume to speak above noise is frequently accompanied by a rise in vocal pitch. Singing also relies on the vocal folds being stretched and thinned to raise the pitch. Often the muscle groups responsible for controlling pitch may fail to relax after the singing or shouting has stopped. Very few people are aware that their speaking voice has become a little higher and continue to use it at that pitch. This puts a strain on the vocal folds which may, in time cause fatigue and weakness. Gliding your voice gently down in pitch, especially using sounds that require a stronger airflow, such as a rolled “r” “Z” or “V”, will help relax the pitching mechanism and restore your usual lower speaking voice.
AMPLIFICATION: It is worth considering using amplification if your job requires you to speak above high levels of background noise for long periods. Teachers of aerobics, swimming or dance often find amplifiers reduce the strain on their voices. An internet search should produce a choice of suppliers and most companies are happy to demonstrate amplifiers or agree loans for a trial period. Vocal strain can also be reduced by using a bell or whistle to attract the attention of others who are outside, upstairs or in another room.
Things to avoid where possible:
VOCAL ABUSE: Try to avoid vocal misuse (or abuse) when possible. This will mean keeping shouting, screaming or prolonged voice use against noise to a minimum. Background noise encourages us to speak louder and higher than we normally do, putting a strain on our voices. Even chatting in cars, buses and aircraft can be vocally tiring because of the engine noise. Coughing and throat clearing also irritate the vocal folds. Try sipping water or sucking glycerin based sweets to reduce the need to cough or throat clear and seek medical help if the cough/throat clearing is chronic or persists after infections have cleared. Coughs can sometimes be indicators of other medical problems such as chest disease, asthma, acid indigestion or side effects of medication.
ATMOSPHERIC IRRITANTS: Try to avoid smoke. If you are a smoker try to give up or at least cut right down. Smoke irritates the mucous membranes of the throat, chest and vocal folds, causing stiffening and swelling. It is related to an increased risk of cancers developing in the lungs and larynx. Seek help from your GP. There are many good programmes to help you stop smoking.
Smoke is not the only irritant however. Traffic fumes carry similar irritants and should be avoided where possible. Turn the car engine off when stationary and hope others do the same. Wear a mask for jobs that expose you to dust, especially wood dust and flour.
ALCOHOL AND DIETARY IRRITANTS: Some spirits such as whisky or brandy have strong fumes which can exacerbate already irritated vocal folds. Alcohol is also very indigestible making acid indigestion more likely. Many other foods can cause acid indigestion including for example, meals with a high fat content, hot spices and onions. Acid indigestion is a problem because acid can spill back up the oesophagus (gullet) from the stomach causing irritation in the throat, increased mucus and guarding in the laryngeal muscles, making the voice production tighter. Occasionally the acid can spill into the larynx at night causing coughing and choking and irritation to the vocal folds directly.
EMOTION: Be aware of your emotional state. Anger, frustration and anxiety can cause a build up of tension, especially when bottled up and left unexpressed. Tension can cause vocal changes, especially in comfort and stamina. Try to deal with the reasons for your anger or anxiety directly and talk to your GP if you feel that stress and your emotional life are related to your voice problem. A short course of counseling may help you find your emotional balance again.
Enjoy your voice and use it well. It is amazingly robust considering the use it has through a lifetime.