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# What is the difference between dB SPL and dB SL?

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###### 2009-08-24 02:18:01

There are several types of dB. dB SPL are decibels measuring sound pressure levels. There is an accepted reference point of 0 dB SPL which equals 20 micropascals = 2 × 10-5 pascals. dB SL are decibels measuring a signal relative to an individuals auditory threshold. For example, if a person's minimum threshold is 30 dB HL (yet another type of decibel measuring how much worse a person's hearing is based on a referential dB level) and a signal is at 40 dB HL, the sensation level of this signal to this individual is 10 db SL (40 dB - 30 dB = 10 dB SL).

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## Related Questions

dB HL stands for decibel Hearing Level, and dB SPL stands for decibel Sound Pressure Level.

The sensation level is measured in decibels. It is frequency specific and starts at 0 dB SL (sensation level) where 0 dB SL is the softest the patient can here a specific frequency. This means that the SL will be different for different people. Everyone's SL will start at 0 but my SL at 1000 Hz may be at 23 db IL and another's may be at 54 db IL.Put more simply, dB SL is the difference between a person's threshold of hearing and the presentation level of a stimulus. If a person's speech reception threshold (SRT) is 10 dB on an audiometer (dB HL) and you present a speech stimulus to them at 50 dB HL on the audiometer, their sensation level would be derived thus: 50 dB (presentation level) minus 10 dB (threshold), which equals a sensation level of 40 dB SL. This is also the procedure for a frequency-specific stimulus (e.g. pure tones): subtract the audiometric threshold (dB HL) from the supra-threshold presentation level (dB HL) and the difference is the sensation level (dB SL).

dB SPL is a comparison of a sound level to what was thought to be the threshold of hearing, although today it is known that the value was too high. dB HL is a measure of hearing loss - a comparison of a subjects hearing compared to a 'normal' standard. As they are measure different things a direct comparison is not possible. The differences between dB HL and dB SPL, arise from isophonic curves. There is no direct (linear) formula to convert this but a set of formulas. For different frequencies, different values should be added. For eg., at 1kHz you can state that 0dB HL is around 2dB SPL while at 250Hz, 0dB HL is 12 dB SPL. db HL = db Hearing Level db SPL = db Sound Pressure Level

The usual soundlevel can be between 0 dB SPL = 20 µPa (threshold of hearing) up to 130 dB SPL (threshold of pain). An average sound level could be at 85 dB SPL. Scroll down to related links and look at "Average sound pressure levels".

The "SL" in dB SL stands for "Sensation Level". The "HL" in dB HL stands for "Hearing Level". The difference between them is that dB SL is based on the hearing ability of an individual test subject, and dB HL is based on the hearing ability of an entire population of test subjects. 0 dB SL is the minimum level at which the test subject can hear a stimulus, usually a tone pip. The actual level will vary with frequency. If we refer to a level of, say, 40 dB SL, we mean a sound that is 40 decibels above a test subject's threshold of hearing. The dB HL scale is the mean dB SL of a large population (theoretically the world-population) of *normal hearing* people. They measured frequency-specific thresholds for alot of people, and averaged them to give the dB HL scale. Finally, dB nHL stands for "normalised hearing level". This is the same concept as dB HL, except the number of test subjects contributing to the average is smaller. It is standard practice for a Hearing Clinic to establish their own dB nHL scale based on all the normal-hearing test subjects they have had access to. This allows a clinic to ensure that the scale they use is correctly calibrated to their test equipment.

It depends on how loud it is. In hearing, the threshold of pain is the sound pressure or sound pressure level beyond which sound becomes unbearable for a human listener. This threshold varies only slightly with frequency. Different values for the threshold of pain are found in the literature: Here are some sound pressure levels SPL in dB and the sound pressure in pascals of the sensed possible threshold of pain: SPL 120 dB = 20 Pa SPL 130 dB = 63 Pa SPL 134 dB =100 Pa SPL 137.5 dB =150 Pa SPL 140 dB =200 Pa

130 dB is an SPL commonly considered to be the threshold of pain. Between 120 and 140. http://ccrma-www.stanford.edu/~jos/st/DB_SPL.html

If you mean the sound pressure level that causes pain, it is about 120 dB SPL.

About 20 dB SPL (sound pressure level).

100 times louder. You will hardly hear a 20 db(SPL) sound at all.

difference between external and internal frontier

The intensity level is 0 dB at the threshold of hearing. The sound pressure level SPL is also 0 dB at the threshold of hearing.

A 10 dB sound pressure level (SPL) is 0.000063 pascal and 100 dB is 2 pascal. Loudness is a problematic psycho acoustic feeling. I don't know what three times louder really means.

The human is is not sensitive to sound intensity (energy), but the human ear is sensitive to sound pressure or to sound pressure level (SPL). It is ranging from 20 micropascals to 150 pascals, that is a SPL of 0 dB (threshold of hearing) to 137.5 dB (threshold of pain). Scroll down to related links and look at "Table of Sound Levels and corresponding Sound Pressure".

dBm us almost exactly the same as dB. The only difference is that there is a reference of 1 Watt = 0 dB, and 1 mW = 0 dBm. Sorry but that is incorrect. db is a ratio and not an absolute value, by it self it means nothing. you got the dbm part right, 1 mW = 0 dbm and it is an absolute value.

Around 150 decibels would make you become deaf, and, unbelievably, around 190 decibels could kill you. It depends also on the listening time. More than 85 dB SPL a long time is not good for your ears. One bang of 140 dB SPL will hurt you very much.

For frequency ranges, we can hear from 20 Hz to 20000 Hz (20 kHz). This is due to a limit on the length of our cochlear basalar membrane. If it were longer, we may be able to hear a greater range. For loudness, using a standard pressure level (SPL) absolute value system, we can hear at soft as 20 dB SPL (just audible whisper) to about 120-140 dB SPL (which will begin to cause hearing loss and irreversible damage).

It's the sound pressure deviation we measure as sound pressure level (SPL). The threshold of pain is known in acoustics as the lowest strength of a stimulus that is perceived by the ear as painful. Because of the different sensitivity of the hearing of people it cannot be given an accurate value. You can find the following rounded values for threshold of pain in various audio articles and books: 140 dB SPL equivalent to 200 Pa 137.5 dB SPL equivalent to 150 Pa 134 dB SPL equivalent to 100 Pa 130 dBSPL equivalent to 63 Pa 120 dBSPL equivalent to 20 Pa Sound pressure levels more than 140 dB at your ears will burst your eardrums. Don't forget that the distance from your ears to the sound source is very important. So keep off.

The ear drums are moved by the sound pressure deviations only. Therefore don't ask for sound intensity. Sound pressure is measured by an SPL meter. Very loud noise is aching. The "threshold of pain" has the value of about 130 dB Sound Pressure Level (SPL). "Permitted Exposure Time Guidelines - SPL" Sound pressure level Lp and permissible exposure time t: 115 dB = 0.46875 minutes (~30 sec) 112 dB = 0.9375 minutes (~1 min) 109 dB = 1.875 minutes (&lt; 2 min) 106 dB = 3.75 minutes (&lt; 4 min) 103 dB = 7.5 minutes 100 dB = 15 minutes 97 dB = 30 minutes 94 dB = 1 hour 91 dB = 2 hours 88 dB = 4 hours 85 dB = 8 hours 82 dB = 16 hours Lower dBs are said to be harmless There are accepted standards for recommended permissible exposure time for continuous time weighted average noise, according to NIOSH (National Institute for Occupational Safety and Health) and CDC (Centers for Disease Control and Prevention) in 2002. For every 3 dBs over 85 dB, the permissible exposure time before possible damage can occur is cut in half.

90 dB + 90 dB is not 180 dB. Decibels are not on linear scale, they are on a logarithmic scale, which better approximates how humans perceive loudness. You can get around the math by adding 3 decibels for every doubling of values, so 90 dB + 90 dB = 93 dB. For example: The sound pressure level of one person in conversational speech is 60dB. The maximum sound pressure level achieved in an underground railway is 100dB. If you have two people speaking, 60dB+60dB=63dB. So the achieved SpL is 63dB. It is not 120dB, which is significantly louder than an underground railway, in fact, it is about the SpL of a rock concert. The maximum theoretical value of sound is 194dB (which probably cant be achieved since it requires a sound-wave to oscillate into negative pressures (in Pascals))

You cannot "measure" the subjective loudness feeling in decibel with a "dB"-meter. You can measure the objective sound pressure with a "sound pressure meter" that shows the sound pressure in pascals or the sound pressure level SPL in dB or dBA.

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