Monitoring in an audio context means keeping a careful check on the sound signal. There are two broad requirements. One, visual monitoring, can be regarded as technical – that the signal voltage keeps within prescribed limits for reasons which will be explained. The second, aural monitoring, uses the operator’s ears not only to listen for technical imperfections which cannot be shown easily (if at all) by visual means, but also to fulﬁl what is at least partly an artistic function – that the balance, perspective, performance and so on are satisfactory. We will take these in turn.
To understand properly the need for this, we must ﬁrst consider dynamic ranges – the difference in dB between the loudest and the quietest signals. Of all the likely sound sources, a symphony orchestra probably has one of the widest dynamic ranges. Table 2.1 in Chapter 2 shows that an orchestra produces a maximum sound level in excess of 100-120 dB(A) at peaks – but there may well be bars in the music which require all instruments to stop playing and the sound level in a quiet studio may then be less than 20 dB(A). The dynamic range of an orchestra is thus likely to be about 100 dB – possibly even more.