No matter how far apart different singing technique, musical style and sound colour might be from one another, the vocal instrument is still the same. For this reason, I have always believed that there must be an operational vocal principle to which all singing is subject. And by exploring this principle it must also be possible to uncover a general structure which encompasses all the sounds that the voice can produce.

After many years of research I have succeeded in finding this general structure! Today this structure has been developed into a simple system that makes it possible to obtain any vocal sound. All sounds I have heard, whatever the musical style, can be categorized and organised in the very same system.

An important step was to isolate and uncover each individual factor separately, such as vowel, pitch, volume and character. Along the way it also became necessary to re-define certain terms and to leave out others because they were too limiting style-wise or simply useless or confusing when working practically. As a replacement we have introduced new terms that work across all musical tastes and styles; for example the amount of ‘metal’ that determined ‘the four vocal modes’.

Fundamental to this system are the four vocal modes (determined by the amount of ‘metal’). These vocal modes are used by all singers in all musical styles all over the world and at all times, at least as far back as the earliest sound recordings. The fact that the production of any sound, any singing technique and any singing style is covered by the four vocal modes and is subjected to the same rules is confirmation to me that the vocal modes constitute the basis of the operational principle of the voice.

By knowing each vocal mode’s advantages and disadvantages we have an overview of all the possibilities of the voice, something we have been missing earlier. We have found a manual for the voice. We have discovered the paths in the voice, and with a map or an overview we are now able to navigate. When singers respect the set of rules for the four vocal modes, as well as their individual advantages and disadvantages, they are able to achieve all sounds and move technically and freely in and out of every musical style whilst avoiding vocal problems at the same time.


The metallic sound

To understand the concept of dividing the sound of the voice into four vocal modes, you must isolate the amount of ‘metal’ in the tone. Some sounds have a more metallic sound than others. All singers, singing all musical styles, sing with metal in the tone although they sound different. A pop/rock singer, for example, uses a more distinct metallic sound than a classical singer does. A DISTINCT metallic tone could be called a harder, more raw or direct sound. In pop/rock music, distinct metallic sounds are used frequently, whilst the metallic sounds in classical singing are more difficult to recognise because they are “covered” or disguised in the classical sound. A metallic tone’s sound may vary but the volume is often relatively loud.

There are different amounts of metal; the metal can be omitted or made more or less distinct. Hence, we distinguish between non-metallic, half-metallic and full-metallic sounds.


Vocal modes

I have classified these non-metallic, half-metallic and full-metallic sounds into different ‘gears’ or techniques called ‘vocal modes’. Thus, all sounds can be divided into these four fundamental modes:


Neutral with air

Female #055
Male #055


Neutral without air

Female #056
Male #056



Female #072
Male #072



Female #097
Male #097



Female #120
Male #120


The modes and their amount of metal can be described as:

Non-metallic = Neutral

Half-metallic = Curbing

Full-metallic = Overdrive

Full-metallic = Edge

Whilst non-metallic is equivalent to Neutral and half-metallic to Curbing, full-metallic is further sub-divided into Overdrive and Edge. From now on, I will often refer to the names of the vocal modes rather than describe their amount of metal.


Changing between modes

It is normal to change between modes and therefore degrees of metal whilst singing and speaking. These changes can occur rapidly, either audibly or inaudibly, within short musical phrases or even within a single word. Conscious control of mode changes enables singers to obtain just about all the sound facets s/he could wish for. Unconscious changes, on the contrary, result in involuntary vocal breaks and are often partly responsible for vocal problems and technical limitations.


Trouble shooting

In my experience, 95% of all technical problems arise from incorrect use of the modes. Such problems can be avoided by knowing, understanding and complying with the advantages and limitations of the modes. Not only does this avoid most mistakes, but it also optimises the use of the modes; where they work the best and give the best sound.

Any choice of mode should be the artist’s deliberate decision rather than the result of a lack of technical expertise or an unconscious habit to change between the modes. Having a good overview of the modes and detailed knowledge of the modes and their advantages and limitations enable singers to vary their expression, to solve their technical vocal problems and to avoid technical limitations.


The centre of the mode is the healthiest

Each mode has a basic position in which it works the best. This is what I refer to as the ‘centre of the mode’. By the centre of the mode I mean to find the exact position of the mode, by which the mode‘s advantages and limitations are being respected and observed. When the limits of a mode are reached, uncontrolled constriction will occur which risk straining the voice.

Around the centre of the mode there is a ‘marginal area’. When you are singing in the marginal area, the various positions are altered slightly, perhaps to achieve certain changes in character, vowel or volume; however, it is still within the limits of the mode (see diagram). The size of the ‘marginal area’ and the possibilities within it vary from mode to mode. For example, in Neutral the ‘marginal area’ is large with many possibilities of variation. In Edge, however, the area is small with very few possibilities of variation. Singing outside the ‘marginal area’ involves a serious risk of wearing the voice. The more you sing exactly in the centre of a mode, the more you will guard against misuse of the voice.

Thus, a healthy and correct technique is characterised by the fact that the majority of the singing is done within the limits of the mode’s ‘marginal area’ and as much as possible in the centre of the mode.

Center of mode