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Do you know that booming sound Waves can damage your ears and may cause permanent or temporary hearing loss? I was researching this fact a couple of months ago to understand sounds and the excellent dB for speakers. Of course, sound waves come in decibels (dB), and you can get the sound decibels by measuring it with a decibel meter. Moreover, the higher the decibel is, the louder the sound would be.
An increase in decibels does not increase the sound arithmetically, but exponentially. For example, if a sound quality increases by 10 dB, the sound waves has become ten times more intense or powerful. If you have a 40 dB sound and increase it to 80 dB, the sound did not become twice as loud as the 40 dB. Instead, it has become exponentially greater than 40 dB. Thus, when choosing the right speakers, you need to be mindful of decibels and levels of sounds.
The loudness of speakers is measured in SPL. SPL means Sound Pressure Level. SPL, of course, is measured in decibels. Aside from SPL, you also need to consider the speaker’s sensitivity and efficiency ratings.
SPL vs. Wattage
Many so-called experts maintain that one should look for speakers with higher wattage because they think that speakers with higher wattage are louder. However, this advice may not be entirely right. In fact, it is wrong. For example, if you would buy two different brands of speakers with the same wattage, you may assume that their volume outputs (SPL) would be the same. But more often, this is not the case. So, you would ask why do two different brands of speakers with the same wattage have different SPL?
The point is that wattage can never be the sole basis of the loudness of a speaker System. It is the dB sensitivity difference that matters. For example, if you compare a 300W speaker to a 600W, you might assume that the 600W speaker system would be louder. However, if the 300W speaker comes with more than 3.01 dB sensitivity, then the 300W would be louder.
Wattage should not be a basis for speaker’s loudness. It should be the SPL or Sound Pressure Level. So, when shopping around for loudspeakers, you should consider instead the max SPL, which may refer to the maximum continuous peak SPL (max SPL) or continuous SPL.
Let me give you another example. Suppose you have two amps: one with 10W rating and another one with a 20W rating. So, in this case, it seems that there is a doubling of wattage or power. You might assume that the 20W speaker system will have twice loudness as the 10W. But this is not the case because such doubling of power only translates to a 3dB SPL increase.
Understanding Speaker Sensitivity Ratings and Efficiency
You may think that speaker sensitivity is difficult to understand. Yet, it is self-explanatory. All you need to do is understand how to measure SPL (Sound Pressure Level) by using an SPL meter. If you have an SPL meter, you can position the SPL meter one meter away from the speaker. Then, connect the speaker to the amplifier and create a signal.
Adjust the amplifier’s level so that it can only deliver one watt to the said speaker. Check the results on the SPL meter. The resulting measurement will be the speaker’s sensitivity. So, the speaker’s sensitivity is basically the SPL level.
You should also know that 88dB sensitivity measurement is about average. However, those measurements below 84 dB are relatively poor. On the other hand, those speakers with 92 dB or higher are worth investing in if you want a very loud and efficient speaker.
But when it comes to speaker efficiency, it will help to note that the higher the speaker SPL rating, the louder it will sound relative to a specific amount of wattage. If you have an 81dB speaker, this speaker can deliver 81 dB sound with one watt of power. However, if you want to increase it to 84 dB, you will need two watts to do that. This is because if you’re going to make an additional 3dB of loudness, you need to double the amp’s power.
From the above example, you will see that the efficiency specification refers to the instrument’s ability to convert electrical energy to sound. You need to double the wattage to increase the SPL level by 3 dB. So, efficiency specification is based on the speaker’s capability to convert electrical energy to sound energy.
Sensitivity and Efficiency: Are they the Same?
If you read through the discussion mentioned above, you will see that sensitivity and efficiency are somewhat the same. But sensitivity and efficiency are different from each other. In the audio system world, however, these two terms are used interchangeably. Technically, they are different, although they refer to the same concept. Moreover, you can convert efficiency specifications into sensitivity specifications and sensitivity to efficiency specification.
As mentioned above, efficiency refers to the power that goes into the speaker that turns into sound. Of course, this value is below one hundred percent because some power sent to the speaker converts to heat.
The loudness of the sound quality is also affected by distance. However, the sound does not decrease or drop per meter. It will be good to note that the sound quality level drops 6 dB per doubling of the sound source’s distance.
What is the Implication of the SPL Ratings and Distance?
When buying a speaker for your studio, for example, you may want to purchase something with 85 dB of SPL for normal listening. You may also want to add 20 decibels of dynamic headroom. So, you will need a speaker with 105 dB peak SPL from your listening location.
You should note that your distance when you listen to the speaker is critical to your listening experience because sound drops by 6 dB as the listening distance doubles. Thus, if your speaker produces 105 dB at a meter distance, its sound would drop to 99 dB at 2 meters and 93 dB at four meters.
What is the Ideal Sound Level for Listening?
The human ears do not actually hear volume, but sound pressure. The closer you get to the sound source, the more sound pressure will hit your ear, and the farther you are from the sound source, the less sound pressure on your ear, though their will be same volume. So, some professional speakers can create more pressure with minimal volume than consumer speakers.
Too high an SPL may damage your ear, and the human ear begins to degenerate at 85 to 95 dB SPL. For example, a standard rock concert can produce an SPL of around 100 to 130 dB.
The ideal way to test a speaker when buying one is to listen to its sound carefully. Yet, you can seldom test a speaker, especially if you are buying it online. So, in the absence of testing, you can look at the specs of the speaker.
Check for its sensitivity specs. The higher the rating of sensitivity, the louder the speaker would be. The average speaker, of course, comes with 87 to 88dB. Yet, a speaker with a 90 dB or more sensitivity rating can be considered excellent.
To help you get a general idea of sensitivity, you can look at the following examples. A whisper has only 15 to 25 dB. However, a home background noise is around 40 to 60 dB. Your normal speaking voice is about 64 to 70 dB, and a lawnmower may be approximately 90 dB. However, the horn of a car may be around 110 dB.
SPL is an essential factor to consider when buying a speaker. The SPL and DB are closely related to each other. Thus, when shopping around for speakers, you need to know the speaker’s max SPL ratings. It will also help if you consider other factors like the speaker’s efficiency, how low the speaker SPL can go, its distortion level, coverage pattern, dynamics, and many other aspects. Besides, you need to shell out more money if you choose a speaker with higher sensitivity.