1) Mounting Height (H) 

This refers to the vertical distance from the horizontal center axis of a wall-mounted speaker to the ground, typically measured in meters. This parameter primarily affects the speaker's performance and listening experience. If mounted too high, the sound energy may be concentrated above the listener's head, resulting in muffled sound in the front row and insufficient volume in the back row.

2) Rated Power (P) 

This is measured in watts (W) and indicates the maximum power a speaker can sustain over a long period of time. However, it is important to note that power does not directly determine coverage area; it affects the maximum loudness of the sound. Insufficient power will result in muffled sound at distance, while excessive power may cause sound to be harsh close up.

3) Sensitivity (S) 

This is measured in decibels per watt-meter (dB/W-m) and refers to the sound pressure level at a distance of 1 meter when 1 watt of power is input. This is an "efficiency parameter"—the higher the sensitivity, the farther sound travels for the same power. For example, a speaker with a 90dB sensitivity will have a wider coverage area than one with an 85dB sensitivity under the same conditions.

4) Coverage Angle (θ) 

The coverage angle of a wall-mounted speaker is generally divided into horizontal coverage angle θh and vertical coverage angle θv, usually expressed in degrees (°). For example, 90° × 60° is a common coverage angle for wall-mounted speakers. A larger angle widens the sound diffusion range, but the energy is more dispersed; a smaller angle results in the opposite.

We assume that the vertical direction is within the speaker's vertical coverage angle, ignoring the speaker's vertical coverage angle. When the speaker is wall-mounted, its sound coverage area projected onto the ground from a vertical view is fan-shaped. The area of ​​this fan, A (m²), can be calculated using the following formula: 

A = (θh/3600)πr²

r (m) is the maximum effective distance of the sound coverage area, and θh (°) is the horizontal coverage angle of the wall-mounted speaker.

1) Calculate the maximum effective distance r (m) of the sound coverage range. 

To facilitate understanding of the calculation method for the coverage area of ​​a single wall-mounted speaker, I will use an example to illustrate. For example, a wall-mounted speaker has a horizontal coverage angle θh of 90°, an installation height H of 2.5 meters, a sensitivity S of 91dB, and a rated power P of 6W. Assuming the target sound pressure level (SPL) needs to reach 80dB, the maximum effective distance of the sound coverage range is r meters. Then,

SPL = S + 10lg (P) - 20lg (r)
r = 10^[(S + 10lg (P) – SPL)/20] = 10^[(91 + 10lg (6) - 80)/20] ≈ 8.69m

This means that when the sound is transmitted 8.69 meters, the sound pressure level drops to 80dB. 

2) Calculate the wall-mounted speaker's coverage area A (m²). 

According to the formula for calculating sector area: 

A = (θh/3600)πr²

This yields a wall-mounted speaker's coverage area A = (900/3600) × 3.14 × 8.692 ≈ 59.31 m².

In large spaces, a single wall-mounted speaker cannot achieve uniform coverage. A coordinated layout of multiple speakers is necessary to compensate for any sound field defects. 

1) Design Principles for Overlapping Coverage 

To avoid significant sound field dips, the coverage areas of adjacent speakers should maintain a 10%-15% overlap.

2) Speaker Spacing Calculation Method

The spacing d can be calculated based on the coverage width D (m) of a single speaker:

d = D × (1 - overlap ratio) = 2r × sin (θh/2) × (1 - overlap ratio)

Using the wall-mounted speakers mentioned above as an example, with a 15% overlap, the installation spacing d = 2 × 8.69 × 0.707 × (1 - 15%) ≈ 10.4 m. This means that one wall-mounted speaker can be deployed at a distance of 10.4 meters.

3) Calculating the number of speakers required for a venue

We calculate the number of speakers required for a venue according to the following principles:
Corridor Scenario, number of speakers N:

N ≈ Corridor Length ÷ d (Rounded up)

For example, for a 30-meter-long corridor, the number of wall-mounted speakers required (based on the wall-mounted speaker specifications above) is N ≈ 30 ÷ 10.4 = 3 
Room Scenario, number of speakers N:    

N = Room Area ÷ Coverage Area of ​​a Single Speaker A

For example, for a 20 x 15 square meter room, the number of speakers required (based on the wall-mounted speaker specifications above) is N = 300 ÷ 59.31 = 5

This is a real-world example of a hotel indoor swimming pool. The client requested a public address speaker that automatically plays background music during the pool's opening hours to enhance the guest experience. They also required clear sound and comprehensive coverage throughout the entire pool. We designed the pool based on the aforementioned wall-mounted speaker design principles. Please see the CAD drawing below for details.

This design fully met the client's needs and received positive feedback.
 

The above calculation method for the coverage area and spacing of wall-mounted speakers is somewhat idealistic. To improve accuracy, professional acoustic simulation software (such as EASE or ODEON) can be used to perform 3D sound field modeling, providing listeners with an immersive audio experience.