Breathing

Speech sounds are made by manipulating the way air moves out of (or sometimes into) the vocal tract. There are a number of ways of doing this, as we will see, but universally across languages sounds of speech are produced on an out-breath. This kind of airflow is called pulmonic (because the movement of air is initiated by the lungs; the Latin word for lung is ‘pulmo’) and egressive (because the air comes out of the vocal tract; ‘e-’, ‘out’, ‘-gress-’, ‘move forwards’): all spoken languages have pulmonic egressive sounds.

Try an experiment. Take a lung full of air and then hum or say ‘aaah’ until you have to stop. Time yourself; it should take you quite a long time before you run out of air. Now repeat this, but breathe out first. This time, you will see that you cannot sustain the same sound for anything like as long. This is enough to show you that a simple sound like ‘aaah’ ([ɑ:]) or ‘mmm’ ([m:] – [:] is the diacritic for long) requires an outbreath with a reasonable amount of air in the lungs.

Now try breathing in while you say ‘aah’ or ‘mmm’. You probably will find that this is quite hard, and you will probably get a more ‘croaky’ voice quality. If you try saying your name while breathing in, you will notice that it feels both unpleasant and difficult; and it doesn’t sound very good either. This is because the vocal tract works best for speech when breathing out, i.e. on an egressive airflow.

The lungs are large spongy organs in the thoracic cavity (chest). They are connected to the outside world via the trachea, or windpipe. The lungs are surrounded at the front by ribs, and at the bottom by the diaphragm. The ribs are attached to one another by intercostal muscles. In breathing in, the diaphragm lowers and the intercostal muscles make the rib cage move upwards and outwards. This increases the size of the thoracic cavity, and so it lowers the air pressure. As a result, air flows into the lungs, and they expand and fill up with air. Once inhalation stops, the diaphragm and the intercostal muscles relax, and exert a gentle pressure on the lungs. Air is forced out of the lungs, generating a pulmonic egressive airflow.