Directivity – Definition & Detailed Explanation – Audio Terms Glossary

What is Directivity in Audio?

Directivity in audio refers to the way sound is radiated from a source in a specific direction. It is a measure of how focused or spread out sound waves are as they travel from a sound source to a listener. Directivity is an important concept in audio engineering as it can affect the overall sound quality and clarity of a sound system.

How is Directivity Measured?

Directivity is typically measured using a polar plot, which shows how sound intensity varies with direction around a sound source. The polar plot is a graphical representation of the directivity pattern of a microphone or loudspeaker. Directivity can also be quantified using a parameter called the directivity index, which is a measure of how focused or spread out sound waves are in a specific direction.

What are the Different Types of Directivity Patterns?

There are several different types of directivity patterns that can be exhibited by microphones and loudspeakers. Some common directivity patterns include:

– Omnidirectional: This type of directivity pattern radiates sound waves equally in all directions, resulting in a 360-degree pickup or coverage pattern.
– Cardioid: A cardioid directivity pattern is heart-shaped and is most sensitive to sound coming from the front of the microphone or loudspeaker, while rejecting sound from the sides and rear.
– Hypercardioid: A hypercardioid directivity pattern is similar to a cardioid pattern but has a narrower pickup angle and greater rejection of sound from the sides.
– Bidirectional: A bidirectional directivity pattern picks up sound from the front and rear of the microphone or loudspeaker while rejecting sound from the sides.

How Does Directivity Affect Sound Quality?

Directivity can have a significant impact on the sound quality of a sound system. By controlling the direction in which sound waves are radiated, directivity can help reduce unwanted noise and reflections, improve clarity and intelligibility, and increase the overall efficiency of a sound system. Directivity can also affect the tonal balance and frequency response of a sound system, depending on the directivity pattern of the microphone or loudspeaker being used.

What Are Some Examples of Directivity in Audio Equipment?

Directivity is a key consideration in the design and implementation of audio equipment such as microphones, loudspeakers, and headphones. For example, shotgun microphones are designed with a highly directional pickup pattern to capture sound from a specific direction while rejecting noise from other directions. Line array loudspeakers use multiple drivers with controlled directivity to focus sound in a specific direction and provide even coverage in large venues. In-ear monitors use custom-molded earpieces to provide a personalized and isolated listening experience with controlled directivity.

How Can Directivity be Controlled or Adjusted?

Directivity can be controlled or adjusted in audio equipment through various means, including the design of the microphone or loudspeaker, the use of acoustic materials and baffles, and the placement and orientation of the sound source. For example, adding a baffle or enclosure around a loudspeaker can help control the directivity pattern and reduce unwanted reflections. Using multiple microphones in an array configuration can also help adjust the directivity pattern and improve sound pickup in challenging acoustic environments. Additionally, digital signal processing techniques can be used to adjust the directivity pattern of a microphone or loudspeaker in real-time to optimize sound quality and coverage.