MULTIMEDIA SOUND. CD-Rom for Multimedia PC, Pounds 55. Cambridge Science MediaTel: 01223 357546.

Jerry Wellington welcomes two CD-Roms that shed light on a neglected area of science.

The topics of light and sound are still popular in science teaching, despite the perhaps unfair lack of attention that the curriculum gives to sound. Both these CD-roms will offer great help to the science teacher and to the student in learning these areas at key stage 4 and above.

The Bradford Technology Ltd (BTL) disc follows the now-familiar menu format which makes it easy for users to find their way around. It gives a comprehensive coverage of light, from rays and shadows, reflection and refraction, to a more complex treatment of lenses, the eye and colour. The treatment of colour is worth the disc money in itself because that mixture of red, green and blue lights which physics teachers try to persuade their pupils makes white light, actually is white. Virtual reality is so much more reliable than the real thing.

Topics such as real and apparent depth and critical angle are treated carefully and rigorously in the customary BTL fashion - this is straight down the line physics as it should be taught. Animations and ray diagrams help in teaching some of the more difficult ideas in optics. As is customary with BTL discs, a spoken commentary (the crisp, northern voice of Bob Gomersall) is given simultaneously with the text on the screen. It is debatable whether this aids understanding, but it will certainly help poorer readers.

The section on sound also gives good coverage, ranging from a look at sound waves - with useful animation showing the difference between transverse and longitudinal - and a useful simulation of another of those experiments which never works “for real”: the measurement of the speed of sound using a wall and its echo. This forms part of the virtual laboratory that is now an expected feature of Bradford discs. The debate about whether experiments should be done on screen or with real objects will live on - but at least this disc’s experiments give different values for the speed of sound ( albeit around about the expected value), which gives it some extra reality.

Light and Sound also has “quizzes” in the form of multiple- choice tests and a glossary of terms which explain ideas such as “lunar eclipse”. Both are ideal for revision.

To delve further into sound and music (a sadly under-exposed topic in school science thanks to the strait-jacket of the national curriculum) the Cambridge disc is just the sequel needed. Its Multimedia Motion disc broke new ground in interactivity, and this one follows suit. Learners and teachers can really interact with this disc by making measurements, studying wave forms, adding sounds and even synthesising new ones. This is what interaction means - not just pointing and clicking a mouse and reading from a screen.

There is so much to this disc that it is difficult to do it justice here. At one level, younger students can simply listen to the sounds of music from different instruments such as the clarinet or the didgeridoo. They can look at the waveforms from each sound and compare (say) the tuning fork with the guitar. At a qualitative level they can see the difference in pitch, complexity, loudness and so on. By recording their own sounds (if they have a microphone) and adding them to the sounds database, they can make more comparisons.

At a higher, more quantitative level, students (probably GNVQ, A-level and above) can analyse sounds using the spectrum analyser. This will show the various frequencies which make up a waveform. My favourite feature is the synthesiser, which allows users to combine up to six different sounds (their own or from the disc) to make a new one and then listen to and analyse it. This allows beats to be created by combining, for example, two sounds with frequencies close to each other. The synthesiser makes good listening - music industry beware.

Both these discs are excellent value for money. They will greatly assist a neglected area of science to be taught and learnt in an interactive, enjoyable way.