Speaker Coverage Patterns: Understanding Dispersion and Directivity

Speaker coverage patterns determine how sound distributes across the listening area. Understanding these patterns enables proper speaker selection and placement for consistent, even coverage throughout venues of various shapes and sizes.

Horizontal and Vertical Dispersion

Speaker dispersion specifies the angle over which sound level stays within a certain range of on-axis level, typically -6 dB.

A speaker with 90° x 50° coverage produces sound at least half the on-axis level throughout a 90-degree horizontal and 50-degree vertical angle.

Specifications list horizontal first, then vertical. “90 x 60” means 90 degrees wide, 60 degrees tall.

How Coverage Affects System Design

Wide coverage speakers can serve large areas with fewer units but may send energy where it is not wanted—walls, ceilings, or outside the audience area.

Narrow coverage speakers aim energy precisely but require more units or careful placement to cover the same area.

Matching coverage to venue requirements prevents wasted energy while ensuring the entire audience receives adequate level.

Frequency Dependency

High frequencies are inherently more directional than low frequencies. Coverage patterns vary with frequency even in well-designed speakers.

Horns and waveguides improve high-frequency coverage control. Pattern control devices maintain coverage across the frequency range.

Specifications typically describe coverage at mid-to-high frequencies. Low-frequency coverage is usually wider and less controllable.

Constant Directivity Horns

Constant directivity (CD) horns maintain specified coverage across a wide frequency range. This provides consistent coverage without the narrowing at high frequencies typical of older horn designs.

JBL, EV, and QSC use CD horn technology in professional speakers. The technology has become standard in modern PA speakers.

CD horns improve intelligibility by delivering consistent high-frequency content throughout the coverage area rather than only on-axis.

Coverage for Different Venue Shapes

Wide, shallow venues suit speakers with wide horizontal coverage. Sound needs to spread laterally more than it needs to throw forward.

Deep, narrow venues benefit from narrower horizontal patterns with longer throw. Energy focused forward serves the audience shape.

Asymmetric venues may need different speakers or rotation angles for different sections.

Vertical Pattern Considerations

Vertical coverage matters for multilevel venues, balconies, and situations where audience height varies significantly.

Too much vertical coverage wastes energy on floors and ceilings, exciting reflections that reduce clarity.

Too little vertical coverage fails to reach audience members at different heights. Standing versus seated audiences have different vertical requirements.

Array Configurations

Multiple speakers can combine to modify coverage. Horizontal arrays of point source speakers widen coverage; splayed configurations create customized patterns.

Line arrays control vertical coverage precisely while horizontal coverage follows individual cabinet specifications.

Subwoofer arrays can be configured for directional bass, reducing low-frequency energy behind the array.

Overlap and Interference

Where speaker coverage overlaps, constructive or destructive interference affects response. Overlapping speakers must be managed carefully.

Some overlap improves consistency—the coverage boundary of one speaker is supplemented by another. Excessive overlap causes comb filtering.

Array configurations exploit controlled overlap for pattern shaping and increased output.

Placement for Coverage

Speaker height affects vertical coverage delivery. Elevated speakers can cover deeper areas without excessive front-row level.

Tilt angle adjusts where coverage falls. Angling speakers down delivers energy to seated audiences rather than over their heads.

Distance from coverage boundaries affects level distribution. Moving speakers further from nearby listeners and closer to distant ones improves front-to-back ratio.

Measuring and Verifying Coverage

Measurement systems like Smaart and SysTune verify actual coverage matches prediction. Walk-around measurements with music also reveal coverage quality.

Coverage predictions from manufacturers assume free-field conditions. Real venues with reflections may differ from predicted patterns.

Significant deviations between predicted and measured coverage indicate placement problems, room acoustic issues, or speaker damage.

Manufacturer Specifications

Reputable manufacturers publish polar pattern data showing coverage at multiple frequencies. This data enables informed speaker selection.

QSC, JBL, EV, and other professional audio manufacturers provide coverage specifications in product documentation.

Comparing specifications between speakers reveals which suits specific applications. A 90x50 speaker differs meaningfully from a 90x60 speaker.

Practical Selection Guidelines

For most music PA applications, speakers with 80-100 degree horizontal coverage suit typical venue widths.

Monitor wedges often have wider patterns (90+ degrees) to cover performers who may move within their area.

Column speakers and line arrays offer narrower vertical patterns, suited for reverberant spaces or precise coverage control.