Acoustics Intro

Covered in the topic of acoustics is it’s aspects within production, on how to control and monitor outputted transmission, how to evaluate the reception of a sound source and more generally how the effects of sound itself behave. Soundwaves will emanate from a source in a space where the air present allows for the outward pulsating crests and troughs of pressure, to distribute in a circular pattern similar to ripples from droplets in water. Sound will travel at 343m/s through air, changing proportionally to varying temperature, and usually goes through an array of ambient effects generated by the room before hitting the ear-drum : reflection / echo (accumulating to create reverberations), refraction, diffraction, and absorption.

These properties will change depending on the room the sound source emits into, as well as the positioning of the sound source itself and even the recipient listener, which is what leads to analysis of a room in an acoustic context being a crucial aspect to audio production and performance. Depending on the dimensions of a room, the sound produced may be perceived with vast difference compared to other listening formats such as headphones, in a room with very large dimensions a short burst of sound may be audible for much longer than usual as it goes on through countless repetitions of the before mentioned effects.

Finding room modes is a way which we can find the acoustic properties of a room, as well as unwanted problems to treat down the line. There are three modes, in order of importance due to their disruptive potential : Axial (resonance between 2 surfaces), Tangential (resonance
between 4 surfaces),and Oblique(resonance between 6 surfaces). Room modes look at the resonances that can occur in a room such as standing waves (nodes) which can create vast variances for the listener in a space. Standing waves being the result of repeating reflections between parallel surfaces in a room where half the emanating wavelength of a sound source is equal to the distance that it travels, leads to these nodes and antinodes which when present in a space causes the listener to hear specific pitches at a much higher (nodes) or lower (antinodes) volume. Obviously being an issue, these areas of standing waves are treated by a number of methods, one example being bass traps which allow for absorption of the energy within a sound signal travelling through the space, dampening it’s reflections and in effect preventing the nodes and antinodes.