Music Technology Glossary Update
Having been away in Finland for the past week or so, I haven’t had the opportunity to post my usual music technology news updates. However, I have been working on a new music theory section for the Podcomplex DAW Guide, as well as an introduction to the physics of sound – both of which will appear on site shortly.
In the meantime, I have added a few new terms to the music technology glossary page. Here are a couple of examples:
- Audio Frequency – The range of audio frequencies directly detectable by the human ear ranges from about 20 Hz to 20 kHz (20,000 Hz). In practice, this is actually closer to 20-17 kHz. Dolphins are believed to hear up to 70 kHz.
- Concert Pitch – Established by the International Organisation for Standardisation in 1955, the agreed reference frequency of 440 Hz for the note called middle A (the A above middle C).
- dB SPL – The unit of measurement for sound pressure level (SPL). In layman’s terms, it could be described as the smallest variation in volume detectable by ear. 0 dB = 20µPa (micro Pascals). The human range of hearing is related to this scale with 0 dB (SPL) being the threshold of hearing, and 120-140 dB(SPL) being the threshold of pain.
- Decibel – A ratio-based measure of the amount of some quality (usually sound level, power or voltage) relative to a set reference amount. It is often qualified to indicate what property is being compared, such as dB(A) or dB(v). A signal-to-noise ratio of 80 dB(v), for example, compares the amplitude of the signal (which we want to hear) and the noise (which we don’t). The signal voltage then becomes the reference point, and so would be called 0 dB(v). The noise voltage would therefore be 80 dB(v) smaller. The logarithmic nature of the decibel allows us to compare two values of enormously different magnitudes with conveniently small numbers. For example, the limits of hearing in terms of absolute pressure level cover the range from 20µPa to 200,000,000 µPa. The same range can be expressed in dB SPL as 0-140 dB SPL.