The spatial property of being crowded together.

What Is Density?

Density is all about how busy and compact something is. Think of a shopping centre on a Saturday lunchtime, full of shoppers and people going about their business. In this case, there is a high density of people, there are lots of shoppers about. Then think about the same shopping centre at midnight. All she shops are closed, the doors are locked and there is only one security guard wandering about. In this situation, there is a very low density of people, there are no shoppers at all and only one security guard.

This picture shows a high density on the left, moving to a low density on the right.

In the same way, we can think of sounds as being of a high or a low density. Using the example of the shopping centre, we can imagine how the sounds would be different in a busy and empty shopping centre. If we were stood in the busy shopping centre and closed our eyes, we would hear people chattering and many footsteps all around us. However, in the empty shopping centre, we would hear only one pair of footsteps ringing out.

Decreasing Density

This sound example begins with a high density of sounds, and over time, moves to a lower density of sounds.

Use Up/Down Arrow keys to increase or decrease volume.

Density and the Clarity of Individual Sounds

In dense soundscapes, we find it very difficult to pick out individual sounds. Sometimes the sounds may be so mixed that we begin to hear a larger ‘cloud’ of sound, itself made up of smaller sounds.  While in soundscapes with a low density, we are easily able to identify individual objects. Obviously, there are many different measures of density in-between these two extremes and sounds may become more or less dense over time.

Density and Clarity

Listen to this example which begins dense and ends sparse. It is difficult to hear any words at the beginning, but gradually we are able to make sense of more and more.

Clouds of Sound

The composer Iannis Xenakis, loved to create dense swarms of sound and he used the terms ‘sound masses’ and ‘clouds’ to describe the sounds that he created.

Concret PH by Iannis Xenakis (Extract).

Listen to the cloud of sounds and how it appears to shift, move and change.

The term ‘cloud’ can be a really useful metaphor for describing the density of sounds – we can imagine clouds of all different shapes, textures and colours from whispy light clouds, to dark dense thunderclouds.

A Granular Cloud

How does it change and evolve over time?


Pick a few different locations and try to determine the change in density for sounds that you hear.

  • Is there a big difference between the most dense and less dense moments, or is this difference only small?
  • How do densities differ between the environments you have visited or within single environments at different times? How do they evolve in time?
  • Stepping back from the detail, what influence does density have on the sonic environment to which you are listening, and to what extent does it influence or even define what you hear?