Sound Measurement: What is Sound and How is it Measured
Sound is a component that is constantly present in our lives, sometimes even in the form of noise.
Sound measurement is an action performed for various reasons. Given our constant exposure to sounds and noises, it is necessary to monitor the decibel levels to which we are continuously subjected, to ensure they remain within legal limits and the recommendations made by the WHO (World Health Organization).
Sound consists of various measurable quantities, and several instruments are used for its measurement, the most commonly used being the sound level meter.
Sound measurement is an essential procedure for evaluating and quantifying the level and characteristics of sound in different environments and contexts. This type of measurement is crucial in sectors such as architectural acoustics, sound engineering, workplace safety, and scientific research.
What is Sound?
Sound is technically defined as the vibration produced by an oscillating body; through its propagation in the air, it reaches people’s hearing and vibrates the eardrum, present in the ear, which makes the sound audible.
Sound is constantly present in our lives. It can come from devices, individuals, the environment—all very different sources—and is therefore highly varied in its intensity, amplitude, frequency, and pressure.
Sounds can be very pleasant, but also quite annoying, to the point of being harmful to human hearing and the environment.
Sound consists of many different components, and measuring each of these will yield different results:
Frequency: measured in hertz (Hz), it is the number of vibrations that occur in one second;
Intensity: allows distinction between weak and strong sounds; intensity is measured in decibels (dB);
Period: the time required to complete one full vibration;
Propagation velocity: the speed at which sound propagates in a given environment;
Wavelength: the distance sound travels in a given period of time;
Wave amplitude: relates to the intensity of the sound we perceive;
Pitch: how high or low a sound is;
Timbre: depends on the type of instrument from which it is emitted.
The most commonly used unit of measurement for sound is the decibel; hearing damage begins at 90 dB if exposure is very prolonged over time, while after approximately 120 dB, pain will begin to be felt.
What is Sound Measurement?
Sound measurement is the process by which objective data on sound is collected to analyze its properties and characteristics. Sound measurement is essential for understanding the sound pressure level, frequency, quality, and other properties of sound in a given environment or situation.
Why is This Procedure Necessary?
Sound is measured for numerous reasons. Knowing its intensity allows for the necessary measures and precautions to be taken for a better quality of life. However, measurements also serve to improve a product (such as a sound-absorbing panel, a musical instrument, or a speaker).
Sound measurements are often performed in very noisy places such as factories using machinery that emits loud noises, airports, highways, venues, but can also be carried out in homes to resolve acoustic problems.
By law, limits are established within which certain environments must maintain a specific sound volume. Particular attention is paid to railways, highways, aircraft noise, industrial noise, construction noise, and sports. The values established by law also differ depending on whether they apply to daytime or nighttime hours, and for isolated cases, a supplementary decibel allowance may be granted to establish a new temporary level (limited, for example, to a single evening).
When is Sound Measurement Required?
Sound measurement is required in many practical situations, such as:
Assessment of noise levels in public places such as schools, hospitals, and offices.
Monitoring compliance with acoustic regulations in industrial environments.
Analysis of architectural acoustics to optimize space design.
Study of the impact of sound on the environment and wildlife.
History of Sound Measurement
The idea of measuring sound dates back to the 19th century, when scientists began developing instruments to quantify sound and better understand its physical properties. The term “sound level meter” was coined in 1913 by one of the pioneers of acoustics, Wallace Clement Sabine, who contributed significantly to research on noise reduction.
Sound Measurement: What Instruments Are Used?
Sound measurement is performed using specialized instruments called sound level meters or decibel meters. These devices are capable of detecting and recording the sound pressure level in decibels (dB) and other acoustic metrics. During measurement, the sound level meter captures ambient sound and provides precise readings that can be analyzed and interpreted.
This instrument is capable of calculating sound amplitude and sound pressure level; each of these devices consists of a microphone for sound detection, a data processing device, and a display where the results obtained from the analysis can be viewed.
The sound is then converted, through the microphone, into an electrical signal that can be read by the device and displayed in dB. Sound varies very frequently, which is why the sound level meter must be very precise to capture all sound fluctuations.
Obviously, since many measurements do not take place only in anechoic chambers but also outdoors or in non-soundproofed locations, it will not always be easy to isolate the sound we want to measure (in enclosed environments, reverberation is always present, while outdoors, background noise and wind are present).
It is necessary to recalibrate the sound level meter before and after each measurement. This action can be performed using an instrument called a pistonphone which, thanks to its sound pressure level, allows the instrument to be adjusted.
Other instruments for sound measurement are dosimeters, portable devices used to measure the amount of daily noise to which a person is exposed.
In addition to these, there are other specialized instruments used to analyze sound, such as acoustic spectrum analyzers and precision microphones. These instruments allow for a more detailed evaluation of sound characteristics and are essential for professionals such as acousticians, sound engineers, and occupational safety technicians.
In conclusion, this is a crucial process for understanding and managing the acoustic environment around us. Thanks to sophisticated instruments and modern technology, we can obtain accurate data on sound and make informed decisions to improve the acoustic quality of our living and working environments.
Discover the sound-absorbing solutions from Marvinacustica for noise reduction.
