Acoustics 1

Lecturer - Andy Wardle 

Understanding the science of acoustics is vital to being an Audio Engineer.

This module on the HNC Sound Production Course comprises of 3 Learning Outcomes:

  • LO1 - the properties, propagation and measurement of sound waves

  • LO2 - Anatomy of the human ear, human perception of loudness and pitch and the masking and placement of frequencies on the critical bands.

  • LO3 - Room acoustics, absorption properties of different materials, causes of reverb.

I found this unit to be truly fascinating. Not only learning about what sound actually is, but also how it relates to what we hear and how we can improve our listening environment to change what we are hearing entirely.

As we learned in LO1, understanding what sound is, how it moves as well as ways of quantifying sound is a key skill in allowing us to mix well both in studio and live. I now understand precisely what a sound wave actually contains, and this leads me to being very wary of cutting frequencies in EQs, ensuring the harmonic content isn't compromised. When mixing, I ensure I listen in different locations in relation to the source to ensure I achieve an accurate picture of the audio.

LO2 covered a lot of information on our ears, as well as the legislation surrounding noise and why this legislation exists. Each part of the human ear plays a part in how we perceive sound (the ear canal, for example, acts like a small bass reflex speaker and amplifies certain frequencies.) Knowledge of how the human ear works can be put to use practically. Two examples could be utilising stereo imaging (as we are aware of directivity due to our pinnae) and ensuring that the mid-range frequencies are clear as our hearing has evolved such that the mids are where our hearing range is most efficient.

As a live engineer, understanding and adhering to legislation over sound is key. Working closely with acousticians can help identify issues and how to resolve them.

LO3 was perhaps the most intriguing of the unit, as it combined knowledge of the previous two Learning Outcomes. We learned about the ideal room ratios, as well as which acoustical issues occurred in rooms (standing waves and flutter echo, for example) as well as exploring what reverb is and how it actually works (Pre-delay, early reflections and the complex reverb tail). Ways in which to treat rooms were covered also, which contained information on absorption properties in relation to frequencies and absorbers such as carpet, and diffusers, as well as where to place them.

We carried out equations using both Sabine and Eyring equations to determine the RT60 of a given room, which was not only intriguing but has proven to be useful practically already.

A report on the speed of sound.

© 2019 Will Derries.

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