Dynamic range (abbreviatedDR,DNR,[1] orDYR[2]) is theratio between the largest and smallest measurable values of a specific quantity. It is often used in the context ofsignals, likesound andlight. It is measured either as a ratio or as abase-10 (decibel) orbase-2 (doublings,bits orstops)logarithmic value of the ratio between the largest and smallest signal values.[3]
Electronically reproduced audio and video is often processed to fit the original material with a wide dynamic range into a narrower recorded dynamic range for easier storage and reproduction. This process is calleddynamic range compression.
| Factor (power) | Decibels (10×log10 power) | Stops (log2 power) |
|---|---|---|
| 1 | 0 | 0 |
| 2 | 3.01 | 1 |
| 3.16 | 5 | 1.66 |
| 4 | 6.02 | 2 |
| 5 | 6.99 | 2.32 |
| 8 | 9.03 | 3 |
| 10 | 10 | 3.32 |
| 16 | 12.0 | 4 |
| 20 | 13.0 | 4.32 |
| 31.6 | 15 | 4.98 |
| 32 | 15.1 | 5 |
| 50 | 17.0 | 5.64 |
| 100 | 20 | 6.64 |
| 1,000 | 30 | 9.97 |
| 1,024 | 30.1 | 10 |
| 10,000 | 40 | 13.3 |
| 100,000 | 50 | 16.6 |
| 1,000,000 | 60 | 19.9 |
| 1,048,576 | 60.2 | 20 |
| 100,000,000 | 80 | 26.6 |
| 1,073,741,824 | 90.3 | 30 |
| 10,000,000,000 | 100 | 33.2 |
The human senses ofsight andhearing have a relatively high dynamic range. However, a human cannot perform these feats of perception at both extremes of the scale at the same time. The human eye takes time to adjust to different light levels, and its dynamic range in a given scene is actually quite limited due to opticalglare. The instantaneous dynamic range of human audio perception is similarly subject tomasking so that, for example, a whisper cannot be heard in loud surroundings.
A human is capable of hearing (and usefully discerning) anything from a quiet murmur in asoundproofed room to the loudest heavy metal concert. Such a difference can exceed 100 dB which represents a factor of 100,000 inamplitude and a factor of 10,000,000,000 inpower.[4][5] The dynamic range of human hearing is roughly 140 dB,[6][7] varying with frequency,[8] from thethreshold of hearing (around −9 dB SPL[8][9][10] at 3 kHz) to thethreshold of pain (from 120 to 140 dB SPL[11][12][13]). This wide dynamic range cannot be perceived all at once, however; thetensor tympani,stapedius muscle, andouter hair cells all act as mechanicaldynamic range compressors to adjust the sensitivity of the ear to different ambient levels.[14]
A human can see objects instarlight[a] or in brightsunlight, even though on a moonless night objects receive one billionth (10−9) of the illumination they would on a bright sunny day; a dynamic range of 90 dB. Change of sensitivity is achieved in part through adjustments of the iris and slow chemical changes, which take some time.
In practice, it is difficult for humans to achieve the full dynamic experience using electronic equipment. For example, a good qualityliquid-crystal display (LCD) has a dynamic range limited to around 1000:1,[b] and some of the latestCMOS image sensors now[when?] have measured dynamic ranges of about 23,000:1.[15][c] Paper reflectance can produce a dynamic range of about 100:1.[16] Aprofessional video camera such as the Sony Digital Betacam achieves a dynamic range of greater than 90 dB in audio recording.[17]
Audio engineers usedynamic range to describe the ratio of the amplitude of the loudest possibleundistorted signal to thenoise floor, say of amicrophone orloudspeaker.[18] Dynamic range is therefore thesignal-to-noise ratio (SNR) for the case where the signal is the loudest possible for the system. For example, if the ceiling of a device is 5 V (rms) and the noise floor is 10 μV (rms) then the dynamic range is 500000:1, or 114 dB:
In digital audio theory the dynamic range is limited byquantization error. The maximum achievable dynamic range for a digital audio system withQ-bit uniform quantization is calculated as the ratio of the largest sine-wave rms to rms noise is:[19]
However, the usable dynamic range may be greater, as a properlydithered recording device can record signals well below the noise floor.
The 16-bitcompact disc has a theoretical undithered dynamic range of about 96 dB;[20][d] however, theperceived dynamic range of 16-bit audio can be 120 dB or more withnoise-shapeddither, taking advantage ofthe frequency response of the human ear.[21][22]
Digital audio with undithered 20-bit quantization is theoretically capable of 120 dB dynamic range, while 24-bit digital audio affords 144 dB dynamic range.[6] MostDigital audio workstations process audio with 32-bitfloating-point representation which affords even higher dynamic range and so loss of dynamic range is no longer a concern in terms ofdigital audio processing. Dynamic range limitations typically result from impropergain staging, recording technique includingambient noise and intentional application ofdynamic range compression.
Dynamic range in analog audio is the difference between low-level thermal noise in the electronic circuitry and high-level signal saturation resulting in increased distortion and, if pushed higher,clipping.[23] Multiple noise processes determine the noise floor of a system. Noise can be picked up from microphone self-noise, preamp noise, wiring and interconnection noise, media noise, etc.
Early 78 rpm phonograph discs had a dynamic range of up to 40 dB,[24] soon reduced to 30 dB and worse due to wear from repeated play. Vinyl microgroove phonograph records typically yield 55-65 dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70 dB.[25]
German magnetic tape in 1941 was reported to have had a dynamic range of 60 dB,[26] though modern-day restoration experts of such tapes note 45-50 dB as the observed dynamic range.[27]Ampex tape recorders in the 1950s achieved 60 dB in practical usage,[26] In the 1960s, improvements in tape formulation processes resulted in 7 dB greater range,[28]: 158 and Ray Dolby developed theDolby A-Type noise reduction system that increased low- and mid-frequency dynamic range on magnetic tape by 10 dB, and high-frequency by 15 dB, usingcompanding (compression and expansion) of four frequency bands.[28]: 169 The peak of professional analog magnetic recording tape technology reached 90 dB dynamic range in the midband frequencies at 3% distortion, or about 80 dB in practical broadband applications.[28]: 158 TheDolby SR noise reduction system gave a 20 dB further increased range resulting in 110 dB in the midband frequencies at 3% distortion.[28]: 172
Compact Cassette tape performance ranges from 50 to 56 dB depending on tape formulation, withtype IV tape tapes giving the greatest dynamic range, and systems such asXDR,dbx andDolby noise reduction system increasing it further. Specialized bias and record head improvements by Nakamichi and Tandberg combined with Dolby C noise reduction yielded 72 dB dynamic range for the cassette.[citation needed]
Adynamic microphone is able to withstand high sound intensity and can have a dynamic range of up to 140 dB. Condenser microphones are also rugged but their dynamic range may be limited by the overloading of their associated electronic circuitry.[29] Practical considerations of acceptable distortion levels in microphones combined with typical practices in a recording studio result in a useful dynamic range of 125 dB.[28]: 75
In 1981, researchers at Ampex determined that a dynamic range of 118 dB on a dithered digital audio stream was necessary for subjective noise-free playback of music in quiet listening environments.[30]
Since the early 1990s, it has been recommended by several authorities, including theAudio Engineering Society, that measurements of dynamic range be made with an audio signal present, which is then filtered out in the noise floor measurement used in determining dynamic range.[31] This avoids questionable measurements based on the use of blank media, or muting circuits.
The termdynamic range may be confusing in audio production because it has two conflicting definitions, particularly in the understanding of theloudness war phenomenon.[32][33]Dynamic range may refer to micro-dynamics,[34][35][36] related tocrest factor,[37][38] whereas theEuropean Broadcasting Union, in EBU3342 Loudness Range, definesdynamic range as the difference between the quietest and loudest volume, a matter of macro-dynamics.[32][33][39][40][41][42]
Inelectronics dynamic range is used in the following contexts:
In audio and electronics applications, the ratio involved is often large enough that it is converted to alogarithm and specified indecibels.[43]
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Inmetrology, such as when performed in support of science, engineering or manufacturing objectives, dynamic range refers to the range of values that can be measured by a sensor or metrology instrument. Often this dynamic range of measurement is limited at one end of the range by saturation of a sensing signal sensor or by physical limits that exist on the motion or other response capability of a mechanical indicator. The other end of the dynamic range of measurement is often limited by one or more sources of randomnoise or uncertainty in signal levels that may be described as defining thesensitivity of the sensor or metrology device. When digital sensors or sensor signal converters are a component of the sensor or metrology device, the dynamic range of measurement will be also related to the number of binary digits (bits) used in a digital numeric representation in which the measured value is linearly related to the digital number.[43] For example, a 12-bit digital sensor or converter can provide a dynamic range in which the ratio of the maximum measured value to the minimum measured value is up to 212 = 4096.
Metrology systems and devices may use several basic methods to increase their basic dynamic range. These methods include averaging and other forms of filtering, correction of receivers characteristics,[43] repetition of measurements, nonlinear transformations to avoid saturation, etc. In more advance forms of metrology, such as multiwavelengthdigital holography,interferometry measurements made at different scales (different wavelengths) can be combined to retain the same low-end resolution while extending the upper end of the dynamic range of measurement by orders of magnitude.
Inmusic, dynamic range describes the difference between the quietest and loudest volume of aninstrument,part or piece of music.[49] In modern recording, this range is often limited throughdynamic range compression, which allows for louder volume, but can make the recording sound less exciting or live.[50]
The dynamic range of music as normally perceived in a concert hall does not exceed 80 dB, and human speech is normally perceived over a range of about 40 dB.[28]: 4
Photographers usedynamic range to describe theluminance range of a scene being photographed, or the limits of luminance range that a givendigital camera orfilm can capture,[52] or theopacity range of developed film images, or thereflectance range of images on photographic papers.
The dynamic range ofdigital photography is comparable to the capabilities ofphotographic film[53] and both are comparable to the capabilities of the human eye.[54]
There are photographic techniques that support even higher dynamic range.
Consumer-gradeimage file formats sometimes restrict dynamic range.[57] The most severe dynamic-range limitation in photography may not involve encoding, but rather reproduction to, say, a paper print or computer screen. In that case, not only local tone mapping but alsodynamic range adjustment can be effective in revealing detail throughout light and dark areas: The principle is the same as that ofdodging and burning (using different lengths of exposures in different areas when making a photographic print) in the chemical darkroom. The principle is also similar to gain riding or automatic level control in audio work, which serves to keep a signal audible in a noisy listening environment and to avoid peak levels that overload the reproducing equipment, or which are unnaturally or uncomfortably loud.
If a camera sensor is incapable of recording the full dynamic range of a scene,high-dynamic-range (HDR) techniques may be used in postprocessing, which generally involve combining multiple exposures using software.
| Device | Stops | Contrast ratio | Optical density |
|---|---|---|---|
| Glossy photograph paper | 7 (7–7+2⁄3)[58] | 128:1 | 2.1 |
| LCD | 9.5 (9–11)[59] | 720:1 (510:1 – 2000:1) | 2.9 (2.7 – 3.3) |
| Typical cellphone camera | ~10[60][failed verification] | varies[e] | |
| Negative film (Kodak VISION3) | 13[62] | 8200:1 | 3.9 |
| Human eye | 10–14[54] | 1000:1 – 16000:1 | 3 – 4.2 |
| OLED orquantum dot | 13.2 – 20.9[63] | 9400:1 – 1960000:1 | 4 – 6.3 |
| High-end DSLR camera (Nikon D850) | 14.8[64] | 28500:1 | 4.5 |
| Digital cinema camera (Red Weapon 8k) | > 16.5[65] | >92700:1 | >5 |
{{cite web}}: CS1 maint: archived copy as title (link),"Archived copy"(PDF).Archived(PDF) from the original on 2016-08-22. Retrieved2016-08-11.{{cite web}}: CS1 maint: archived copy as title (link),"The data aquisition [sic] method of the Sussex MK4 EIM system"(PDF). 24 April 2014.Archived(PDF) from the original on 2016-08-27. Retrieved2016-08-11.The dynamic range of human hearing is [approximately] 120 dB
The practical dynamic range could be said to be from the threshold of hearing to the threshold of pain [130 dB]
the overall dynamic range of human hearing roughly encompasses a full 140 dB
{{cite journal}}:Cite journal requires|journal= (help)The very quietest perceptible sound is about -8dbSPL
On the other hand, you can also see in Figure 1 that our hearing is slightly more sensitive to frequencies just above 1 kHz, where thresholds can be as low as −9 dB SPL!
The peak sensitivities shown in this figure are equivalent to a sound pressure amplitude in the sound wave of 10 μPa or: about -6 dB (SPL). Note that this is for monaural listening to a sound presented at the front of the listener. For sounds presented on the listening side of the head there is a rise in peak sensitivity of about 6 dB [−12 dB SPL] due to the increase in pressure caused by reflection from the head.
The upper limit for a tolerable intensity of sound rises substantially with increasing habituation. Moreover, a variety of subjective effects are reported, such as discomfort, tickle, pressure, and pain, each at a slightly different level. As a simple engineering estimate it can be said that naive listeners reach a limit at about 125 dB SPL and experienced listeners at 135 to 140 dB.
A nominal figure for the threshold of pain is 130 decibels ... Some sources quote 120 dB as the pain threshold
the threshold for pain is between 120 and 140 dB SPL.
Digital audio at 16-bit resolution has a theoretical dynamic range of 96 dB, but the actual dynamic range is usually lower because of overhead from filters that are built into most audio systems." ... "Audio CDs achieve about a 90-dB signal-to-noise ratio.
With use of shaped dither, which moves quantization noise energy into frequencies where it's harder to hear, the effective dynamic range of 16 bit audio reaches 120dB in practice, more than fifteen times deeper than the 96dB claim. 120dB is greater than the difference between a mosquito somewhere in the same room and a jackhammer a foot away.... or the difference between a deserted 'soundproof' room and a sound loud enough to cause hearing damage in seconds. 16 bits is enough to store all we can hear, and will be enough forever.
One of the great discoveries in PCM was that, by adding a small random noise (that we call dither) the truncation effect can disappear. Even more important was the realisation that there is aright sort of random noise to add, and that when the right dither is used, the resolution of the digital system becomesinfinite.
{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)