Modern receivers’ functionality and ease of use allow you to set up any home theater speaker system. For the sound quality to bring you only pleasant emotions, paying special attention to audio calibration and room acoustics is important. Each parameter can be adjusted automatically or manually based on your personal preferences, and it will be a very educational and rewarding experience. And the following guide will hopefully be of help to you.

The science of sound

Sound is energy that travels through space, is picked up by the human ear, and is converted into electrical signals that our brain perceives as sound.  And the force with which sound waves reach human sensors is called amplitude, and our consciousness interprets it as loudness, i.e. high-frequency sound streams have a greater amplitude of propagation and we hear the loud shrill sound and low-frequency sound streams have a lower frequency of movement and we feel quiet, soft and calm tones.

Let’s leave all these processes to physics and look at a subfield like acoustics. Acoustics studies in detail the propagation and oscillation of sound waves in space, their interaction with the environment, and how sound behaves in different spaces, especially closed ones. Understanding the role of room acoustics can help you optimize sound quality and create a comfortable space to listen.

The size, shape, materials used in a room, and the presence of furniture all affect the time it takes for sound waves to travel through a room. For example, irregularly shaped rooms can cause sound reflections and echoes, while cluttered rooms with lots of soft furnishings tend to absorb sound and reduce echoes. Minimalist spaces can result in more pronounced sound reflections.

Therefore, to improve the acoustics of the room, you can use various acoustic devices, such as bass traps (placed in the corners of the room), which reduce the accumulation of bass and improve the tonal balance. To create a more even distribution of sound throughout the room, devices such as diffusers help, because, unlike traps, they do not absorb sound waves, but scatter them.  They are often used in recording studios and home theaters to reduce the number of “hot spots” of sound.

Also popular are special absorptive panels mounted on walls and ceilings to eliminate sound reflections, reduce echo, and improve sound clarity. Conversely, there are additional reflectors that direct sound to specific listening areas, creating a more immersive sound experience.

Common audio issues in un-calibrated systems

Some fairly common acoustic problems end up preventing spectacular audio reproduction from your home theater and they are worth paying attention to:

1. Echo is a major problem in acoustics, resulting in delayed and often overlapping sound signals that completely ruin the listening experience.

2. Absorption – when the decor of the room absorbs the sound stream. Furniture, and curtains – all can absorb sound energy, making the sound dull and lifeless.

3. Lack of bass – a significant problem that occurs when the acoustics of the room or the limitations of the audio equipment do not allow for proper reproduction of low-frequency sound waves.

4. Uneven volume levels at different frequencies. For example, characteristics of the audio equipment or the acoustics of the room can create an imbalance in sound perception – some sounds may be overly prominent while others are barely audible, resulting in a lack of overall cohesiveness and immersion in the listening atmosphere.

5. Stereo imbalance is caused by improper placement or calibration of the left and right speakers, which also distorts the perception of the sound and image.

Automated vs manual calibration 

Modern AV receivers, including models under $1000, are equipped with a convenient and useful option – sound tuning (calibration), which determines the good sound quality. Automatic measurement of the listening area greatly simplifies the correct installation and competent adjustment of the home theater.

Modern applications such as Audyssey MultEQ Editor (Denon/Marantz), YPAO (Yamaha), and others are convenient and easy to use, quickly, accurately, and independently measuring the size and shape of the room, saving you time. By eliminating problems such as echo and standing waves and taking into account the room’s acoustics, these technologies provide a balanced sound for different home theater zones and listeners.

Tools and techniques for sound calibration

If your receiver does not have cool features like automatic home theater speaker calibration, you can use special microphones. These are sensors that respond to changes in air pressure caused by sound waves. This received signal is then processed by the microphone amplifier and displayed on the screen as dB sound pressure levels.

There are a few critical points to optimizing home audio systems, and I encourage you to stick to them. It is worth positioning the speakers (at the correct height, angle, and distance from the listening position) to create a balanced sound field, and it is important to adjust the frequency response of specific speakers.

Equalizing the volume levels of each speaker will help create a more cohesive and homogeneous sound. And, if possible, add sound-absorbing materials to reduce reflections, or the opposite – reflective panels – if the acoustic characteristics of the room require it.

By considering the unique characteristics of your listening area and using the methods and tools listed above, you can achieve an even and pleasing sound from your speaker system.