When selecting a speaker, one of the most important factors to consider is loudness. Loudness determines how well your music or sound will be heard in different environments and from various distances.
Knowing the loudness of a speaker can help you compare different models and make an informed purchase decision.
It is possible to calculate how loud a speaker will play by using the SPL (Sound Pressure Level) value that is printed on all speaker specification sheets. With this value, we can calculate the speaker’s maximum SPL, which is the peak loudness of a speaker.
In this article, we’ll explain how to measure speaker loudness and provide tips on getting the best results, covering:
- What is the unit of sound?
- How loud is my speaker?
- How do you compare speaker loudness?
- What determines the loudness of sound in a speaker?
- What is perceived loudness?
What Is The Unit Of Sound?
Before we can specify how loud something is, including a speaker, we need to understand the unit of sound which is the decibel.
What Is A Decibel?
A decibel is a unit of measure for sound intensity or loudness. It is a logarithmic scale used to measure the ratio of physical quantities, such as the ratio between two different sounds.
This scale allows us to compare levels of sound that are vastly different in intensity. The decibel scale is measured on a range from 0 dB, which is the threshold of human hearing, to 140 dB and beyond.
At volumes above 130dB, the sound is painfully loud. [source]
Since we measure the loudness of a speaker in decibels, it is important to grasp the concept of a decibel and the decibel scale.
Decibels help us compare different sounds that are very different in loudness. So, a sound that is 100dB on the scale, is louder than one that is 50dB.
You might assume that a speaker playing at 100dB is twice as loud as a speaker playing at 50dB, however, this is not the case.
The decibel scale works on a logarithmic basis. This means that for every increase of 10 dB, the perceived loudness doubles. For example, if you increase the sound level from 40dB to 50dB, we will perceive the sound to be twice as loud.
Knowing how decibels work can help us understand the loudness of a speaker and compare the loudness between speakers.
How Loud Is My Speaker?
In order to determine how loud your speaker is, you will need the SPL value (or sensitivity) of the speaker as specified on the specification sheet.
For example, you may find something like the following written on the speaker specification sheet:
- 90dB @ 1W / 1m (Measured on axis at 1W, 1m in 2π anechoic environment)
This SPL value is determined by placing the speaker in an anechoic chamber, 1 metre away from a measurement microphone, with 1 watt of power supplied to the speaker. [source]
In order to know how loud your speaker can get before breaking, you need to know this SPL value measured at 1W/ 1m which you can find on the specification sheet.
For example, let’s assume you have a speaker with the following SPL value taken from the specification sheet:
- 97dB @ 1W / 1m
Using the following formula, you can calculate how loud the speaker will be:
- Max SPL = SPL @ 1W/1m + 10log(Max Power)
Where max power is the RMS (Root Mean Square) power handling or continuous power handling that is taken from the specification sheet.
How Do You Compare Speaker Loudness?
It is important to understand how to compare the loudness of speakers when making a purchase decision. You can compare speaker loudness by calculating the maximum SPL (sound pressure level) of each model using the SPL value specified on their specification sheets.
Using this information, you can find out which speaker will produce a louder sound at its full potential.
Let’s use a real-world example, like this C15Nspeaker from Jensen.
For this speaker model, the SPL is 96.3dB @ 1W / 1m and the RMS power handling is 50W.
Putting these values into our formula above, we can calculate the maximum SPL of this speaker as:
- Max SPL = 96.3dB + 10log (50)
- Max SPL = 113.2dB
It is essential to point out that the above figure is just an estimate or approximation as it does not include additional influences such as the impact of the enclosure or the room environment of the speaker, which both have an effect on loudness.
Using this above equation, you can now calculate the maximum SPL for different speakers and compare them.
Some speaker manufacturers will specify the SPL value of their speakers in a similar way to the following:
- 90dB @ 2.83V / 1m
Some speaker manufacturers specify this “2.83V / 1m” value, as using voltage (V) can make the SPL value seem larger than it actually is for lower impedance speakers. Be careful not to fall for this.
In this instance, you must convert this “2.83V / 1m” value to the equivalent 1W / 1m value.
To do this, we need to know the nominal impedance of the speaker. If the nominal impedance of the speaker is 8 ohms, then we do not need to do anything or make any conversion.
For example, these two speakers, which both have an impedance of 8 ohms, have the same SPL value.
- Speaker A = 90dB @ 1W / 1m
- Speaker B = 90dB @ 2.83V / 1m
If the nominal impedance is not 8 ohms, however, you must add or subtract 3dB depending on the speaker’s impedance.
For example, if this same speaker has an impedance of 4 ohms, then the equivalent SPL value is
- Speaker A = 90dB @ 1W / 1m
- Speaker B = 87dB @ 1W / 1m
If the nominal impedance is 2 ohms, then the equivalent SPL value is:
- Speaker A = 90dB @ 1W / 1m
- Speaker B = 84dB @ 1W / 1m
You can see that every time we half the input power, we lose 3dB and every time we double the input power, we gain 3dB.
Keep in mind that even though a speaker might have a high maximum SPL rating, it doesn’t necessarily mean that it will be consistently loud throughout its frequency range. You’ll need to look at the frequency response curve of each speaker to determine how consistent their sound is.
By understanding how to calculate and measure the loudness of a speaker, you can make an informed decision and purchase the right model for your needs.
What Determines Loudness Of Sound In A Speaker?
The loudness of sound in a speaker is determined by the power output and sensitivity of the speaker, as well as the size and sound properties of the room it is placed in.
Power output refers to how much wattage a speaker can produce, while sensitivity measures how efficiently a speaker converts power into sound.
The loudness of a speaker increases with higher power output and sensitivity.
What Is Perceived Loudness?
Since sound is subjective, it is important to take a step away from the mathematics and point out that a 3dB difference in sound pressure can be hard to detect.
If you are a trained listener, you may be able to detect a 3dB difference in sound level. However, most people will not hear the difference between 90dB and 93dB.
Because of the logarithmic nature of the decibel scale, a 10dB variation in sound level will be perceived by a listener as being twice as loud.
For example, a sound of 90dB will be perceived as being twice as loud as a sound of 80dB.
It is important to bear this in mind when dealing with dB values to try and fully comprehend how loudness is perceived in the real world.
In conclusion, the loudness of sound in a speaker is determined by the power output and sensitivity of the speaker, as well as the size and sound properties of the room it is placed in.
When considering how loud a speaker will be perceived by listeners, remember that a 10dB increase in sound level will be perceived as twice as loud.
When comparing two speakers to determine which will play the loudest, it is best to compare their maximum SPL values using the following formula.
Max SPL = SPL @ 1W/1m + 10log(Max Power)
Understanding these factors can help you make an informed decision when purchasing speakers.
To read and learn more about speaker SPL, I recommend this article which covers the topic in greater detail: