In September 2108, Patricia de Lille gave a speech in the Cape Town City Hall as part of the opening of a revamped hall, which had taken nine months to complete.

Despite the hall having a reverberation time of 2.3 seconds, her speech was clear, understandable and free from distortion. The reason for this was that the public address (PA) system she used was designed by me. Thus, there was no ‘feedback howl’ and no ‘slapback stutter’. The latter occurs when there is a distinct echo during the speech, as in “hello, hello I hope hope you can can hear me me”.

The reason for these faults not being in the City Hall PA system is that the hall is correctly designed. I will explain the main elements of a ‘correct design’ as follows:

A PA system is supposed to allow people (the audience) to hear the speaker with clarity. Thus, the level of the speech as heard by an audience member should not be more than about 75 dBA. Consider the venue as being more or less a rectangle, with the speaker on the stage at one shorter end of the rectangle. Then the PA system loudspeakers should be placed at intervals down the left and right of the rectangle. Typically, four loudspeakers per side, depending on the size of the venue. The power of the loudspeakers should be set such that the sound pressure level, on axis with the loudspeakers, is 72 dBA from each loudspeaker. And so on. There are other rules for the spacing of the loudspeakers on each side of the rectangle. It is not very complicated. In point of fact, it is so not complicated that sound people have been setting up sound systems since 1930 which are free from ‘feedback howl’ and ‘slapback stutter’. The Nazi rallies speeches, if you listen to the audio as recorded at the time, are clear and understandable. The broadcasts of Winston Churchill, Roosevelt . . . the intensely moving speech by Martin Luther King (‘I Have a Dream’), the JF Kennedy ‘Moon Speech’ . . . all understandable.

More modern speeches, less so. The PA system at the Cape Town International Stadium is awful. You do not need to be particularly picky to notice this. It is just plain unintelligible. The contractor was told it was no good and was paid additional money to fix it. Still terrible.

Then we now hear all the speeches of the political parties. The PA systems are terrible. We hear that the “DA A A is committed ed ed to change ange . . .” We hear that “the ANC CCC cannot t t t fall back k k . . .” and so on.

The reason for this is that the sound system suppliers have lost the plot. They want to maximise the hire rate they charge for the equipment and so, instead of doing the correct (and simple) design, they load up the stage with some bass bins, mid-high speaker stacks and line arrays, 5 000 W amplifiers and produce a sound system suitable for a rock concert.

Unfortunately, it is no good at all for speech and the above problems result. This, of all things, has to be the dumbest thing ever. The very purpose of a political rally is to convince people listening to you that you are the one to follow; that you are the one to believe; that your cause is the best. If they cannot even understand what you have said, they might as well scrap the T-shirts, pour away the cooldrink and save money on the banners and the sound system. But it never happens. All the political parties have some person who thinks they know all about sound. This person uses phrases such as “it’s the best we can do, given the acoustics of the venue”. All rubbish. They should try harder.