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Listeners may describe one sound system as pure and natural, and another — as booming, harsh, or voiceless. Often the reason is not the volume or even the quality of the equipment, but the incorrect ratio of low, medium and high frequencies.
This ratio is called frequency balance. The intelligibility of speech, the naturalness of music and the comfort of listeners depend on it.
What is frequency balance
Frequency balance — is the distribution of sound energy between different parts of the audible range. Simply put, it shows which frequencies are larger in sound, which are smaller, and how well they are consistent with each other.
The sound range can be divided into three parts:
- low frequencies create a sense of depth, weight and power;
- medium frequencies transmit the bulk of the voice and timbre of musical instruments;
- high frequencies responsible for detail, clarity and sense of space.
The boundaries between these areas are arbitrary. In practice, specialists additionally distinguish subbass, low middle, upper middle and other ranges.
Good balance does not mean that all frequencies must sound at the same level. The result depends on the room, the purpose of the system and the material being reproduced. Speech intelligibility is especially important for the conference room, and on the concert stage full bass, natural vocals and expressive instrument sound are added to it.
How the balance is related to the frequency response
According https://stagematch.com/ the amplitude-frequency response, or frequency response, shows how the sound level changes depending on the frequency. According to the graph, you can see pronounced rises and falls in different parts of the spectrum.
If the low frequencies are noticeably amplified, the sound can become booming. A dip in the middle is capable of impairing voice intelligibility, and excess high frequencies are often perceived as harshness.
However, one frequency response does not describe the sound completely.
The results are also influenced by:
- reflections and reverberation times;
- phase relationships between loudspeakers;
- delays between the main system and additional lines;
- the directionality and location of the acoustic systems;
- background noise level;
- equipment distortions.
Therefore, a beautiful graph does not guarantee good sound, and a perfectly straight line is not always the only correct goal.
What is the main goal of frequency balance
The main task is — to convey sound to the listener without unwanted coloring and a clear predominance of individual frequency areas.
A properly structured balance helps solve several problems.
Make speech legible
The listener must understand the speaker without having to listen. Excessive bass can mask the voice, and a too emphasized upper middle makes speech unpleasantly harsh.
At the same time, legibility depends not only on equalization. If there is too much reverberation or high background noise in the room, setting up the remote control alone will not fix the problem.
Maintain natural timbre
The voice, piano, guitar or wind instrument have a complex spectrum. If some frequencies are overly amplified or weakened, the source stops sounding natural.
Frequency correction should emphasize the nature of the source, rather than turning all voices and instruments into an equally processed signal.
Provide comfort
An excessively bright or booming sound is quickly tiring. The listener may not understand the technical cause of the discomfort, but it becomes difficult for him to perceive speech or music during a long event.
A balanced system can sound convincing without excessive volume.
Get a similar sound throughout the hall
In a good project, viewers in the first and last rows receive a comparable spectral picture. It is impossible to achieve absolutely the same result at each point, but there should be no sharp differences between the zones.
If the front of the system sounds sharp, the center — is booming, and speech is lost on the balcony, the problem may lie not only in the equalizer, but also in the location, directionality or matching of the loudspeakers.
Where balance disturbances come from
The final sound is influenced by the entire chain — from the source to the listener.
Source and microphone
Two microphones can transmit a single voice in different ways. Additionally, the result is changed by the distance to the source, the direction of the microphone and the proximity effect. The incorrect position of the microphone cannot be completely corrected by equalization.
Acoustic systems
Each model has its own frequency response and directionality. Even a high-quality loudspeaker can give an unsatisfactory result if it does not fit in power, coverage angle or operating range.
Arrangements of loudspeakers
The walls, floor and ceiling reflect the sound. Installing a speaker system near the surface can amplify some frequencies, and crossing the coverage areas of several loudspeakers — creates rises and dips.
The premises
The dimensions of the hall, the shape of the walls, finishing materials, armchairs and the number of spectators affect the sound. Problems are especially noticeable in rooms with a large number of hard reflective surfaces.
Setting up equipment
Errors in partition frequencies, levels, polarity, and delays can disrupt the matching of subwoofers, main system, frontfills, and delay lines. In such a situation, trying to fix everything with a master equalizer usually only complicates the setup.
How to understand that the balance is upset
Some problems can be pre-identified aurally:
- hum and muttering — low or low mid frequencies predominate;
- muddy sound —instruments and voices do not separate well from each other;
- loudness — the upper middle is overly underlined;
- sharpness and hissing — too much high frequency energy;
- dull sound —lacking upper middle and high frequencies;
- thin voice — its lower part is excessively weakened;
- different sounds around the hall — problems with coverage, reflections, or system matching are likely.
These definitions are subjective and do not indicate the exact frequency. They help describe the problem, but it is advisable to make final decisions after measurements.
How to adjust the frequency balance
How says https://stagematch.de/ the work begins not with an equalizer, but with the formulation of the problem. The specialist must understand what will be heard on the site, how many spectators are in the hall and what areas need to be voiced.
Next, check:
- Correct selection and placement of acoustic systems.
- Polarity, levels and temporal matching of components.
- Operation of subwoofers, main system and additional zones.
- Frequency response at several points in the hall.
- Speech intelligibility and sound of familiar musical material.
For measurements, a calibrated microphone and specialized software are used. One point does not reflect the picture throughout the room, so measurements are taken in different parts of the viewing area.
After this, an equalizer is used. It is usually safer to gently ease a problematic climb than to try to compensate for a deep failure with a significant boost. Failure can be caused by mutual subtraction of sound waves, and adding a level will not eliminate its cause.
The final assessment is carried out by ear. Measurements show what is happening to the system, and listening helps to understand whether the result corresponds to the task of the event.
Which the equalizer cannot fix
Equalization is useful, but its possibilities are limited.
She is not capable of:
- change the failed room geometry;
- remove long reverberation;
- correct incorrect loudspeaker direction;
- eliminate deep gaps caused by phase subtraction;
- make a weak system suitable for a large hall;
- compensate for incorrect microphone position;
- provide the same coverage if the acoustics are not arranged correctly.
Such problems are solved by changing the location of equipment, adjusting delays and phase relationships, acoustic treatment of the room or revising the system design.
Frequency balance for different sites
In the theater and cultural center, the naturalness of the voice and the intelligibility of the text are especially important. Concerts require maintaining vocals and instruments while providing a controlled low-frequency range. In the conference room, speech comes to the fore, and unnecessary hum and noise should be minimal.
In an open area there are fewer reflections from the walls, but other difficulties appear: long distances, wind, background noise and the need to evenly cover a significant area.
There is no universal setting for all objects. Even identical speaker systems in two different rooms will require different corrections.
Conclusion
According https://stagematch.fr/ frequency balance — is not just the amount of bass or treble. This is a coordinated sound of the entire system, in which speech remains understandable, music — natural, and listeners do not experience discomfort.
This result can only be achieved comprehensively: select and place the equipment correctly, take into account the properties of the room, coordinate loudspeakers, perform measurements and carefully apply equalization.
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