Sound and noise
Sound refers, generically, to a vibration that travels, as a sound wave, in a resilient medium. Sound causes pressure and density fluctuations in the air. These fluctuations travel in waves and propagate spherically around the source of the sound. Tight, rapid sound waves have a short wavelength λ and therefore high frequency (e.g. beeping), whereas wide, slow waves have a low frequency (e.g. humming). The higher the amplitude A (= extent of pressure fluctuations) of the wave, the higher the sound level.
Noise is the biggest source of stress in office settings. It is not physically measurable because noise perception is very subjective. Therefore, sound which is perceived as undesirable, disruptive or harmful depends only partly on objective parameters such as sound level and frequency.
Different sounds are perceived as disruptive to differing degrees. For example, the monotonous buzzing of a device has a less disturbing effect than speech sounds at the same level of volume. The irrelevant speech effect describes the negative influence of speech noise on our productivity – irrespective of whether we understand it or not. The cocktail party effect occurs when the brain isolates individual voices from a clamour, in order to follow a conversation. Due to these two effects, conversations in office settings represent the biggest source of distraction.