- Amplitude, reported on the decibel (dB) scale, measures its pressure or forcefulness. The more amplitude a sound has, the louder it is. The logarithmic decibel scale measures differently than a linear scale. For example, every increase of 10 dB on the decibel scale is equal to a 10-fold increase in sound pressure level (SPL).
- Despite the overwhelming burden of hearing loss and balance disorders, the search for therapeutics to treat these conditions remains one of the largest areas of unmet needs in medicine. At Decibel, we are exclusively focused on discovering and developing transformative treatments to restore and improve hearing and balance.
Decibel amplifies stories and issues important to Austin by listening to the community and encouraging dynamic discussions. It is the new News & Public Affairs initiative from KLRU-TV, Austin PBS.
Here are some interesting numbers, collected from a variety of sources, that help one to understand the volume levels of various sources and how they can affect our hearing.
Environmental Noise | |
| Weakest sound heard | 0dB |
| Whisper Quiet Library at 6' | 30dB |
| Normal conversation at 3' | 60-65dB |
| Telephone dial tone | 80dB |
| City Traffic (inside car) | 85dB |
| Train whistle at 500', Truck Traffic | 90dB |
| Jackhammer at 50' | 95dB |
| Subway train at 200' | 95dB |
| Level at which sustained exposure may result in hearing loss | 90 - 95dB |
| Hand Drill | 98dB |
| Power mower at 3' | 107dB |
| Snowmobile, Motorcycle | 100dB |
| Power saw at 3' | 110dB |
| Sandblasting, Loud Rock Concert | 115dB |
| Pain begins | 125dB |
| Pneumatic riveter at 4' | 125dB |
| Even short term exposure can cause permanent damage - Loudest recommended exposure WITH hearing protection | 140dB |
| Jet engine at 100' | 140dB |
| 12 Gauge Shotgun Blast | 165dB |
| Death of hearing tissue | 180dB |
| Loudest sound possible | 194dB |
| OSHA Daily Permissible Noise Level Exposure | |
| Hours per day | Sound level |
| 8 | 90dB |
| 6 | 92dB |
| 4 | 95dB |
| 3 | 97dB |
| 2 | 100dB |
| 1.5 | 102dB |
| 1 | 105dB |
| .5 | 110dB |
| .25 or less | 115dB |
| NIOSH Daily Permissible Noise Level Exposure | |
| Hours per day | Sound level |
| 8 | 85dBA |
| 6 | 86dBA |
| 4 | 88dBA |
| 3 | 89dBA |
| 2 | 90dBA |
| 1.5 | 92dBA |
| 1 | 94dBA |
| .5 | 97dBA |
| .25 or less | 100dBA |
| 0 | 112dBA |
| Perceptions of Increases in Decibel Level | |
| Imperceptible Change | 1dB |
| Barely Perceptible Change | 3dB |
| Clearly Noticeable Change | 5dB |
| About Twice as Loud | 10dB |
| About Four Times as Loud | 20dB |
| Sound Levels of Music | |
| Normal piano practice | 60 -70dB |
| Fortissimo Singer, 3' | 70dB |
| Chamber music, small auditorium | 75 - 85dB |
| Piano Fortissimo | 84 - 103dB |
| Violin | 82 - 92dB |
| Cello | 85 -111dB |
| Oboe | 95-112dB |
| Flute | 92 -103dB |
| Piccolo | 90 -106dB |
| Clarinet | 85 - 114dB |
| French horn | 90 - 106dB |
| Trombone | 85 - 114dB |
| Tympani & bass drum | 106dB |
| Walkman on 5/10 | 94dB |
| Symphonic music peak | 120 - 137dB |
| Amplifier, rock, 4-6' | 120dB |
| Rock music peak | 150dB |
NOTES:
- One-third of the total power of a 75-piece orchestra comes from the bass drum.
- High-frequency sounds of 2 - 4,000 Hz are the most damaging. The uppermost octave of the piccolo is 2,048 - 4,096 Hz.
- Aging causes gradual hearing loss, mostly in the high frequencies.
- Speech reception is not seriously impaired until there is about 30 dB loss; by that time severe damage may have occurred.
- Hypertension and various psychological difficulties can be related to noise exposure.
- The incidence of hearing loss in classical musicians has been estimated at 4 - 43%, in rock musicians 13 - 30%.
- Recent NIOSH studies of sound levels from weapons fires have shown that they may range from a low of 144 dB SPL for small caliber weapons such as a 0.22 caliber rifle to as high as a 172 dB SPL for a 0.357 caliber revolver. Double ear protection is recommended for shooters, combining soft, insertable earplugs and external ear muffs.
Statistics for the Decibel (Loudness) Comparison Chart were taken from a study by Marshall Chasin, M.Sc., Aud(C), FAAA, Centre for Human Performance & Health, Ontario, Canada. There were some conflicting readings and, in many cases, authors did not specify at what distance the readings were taken or what the musician was actually playing. In general, when there were several readings, the higher one was chosen.
ADDITIONAL RESOURCES -
The National Institute for Occupational Safety and Health (NIOSH)
American Tinnitus Association – Information and help for those with tinnitus
Hear Tomorrow – The Hearing Conservation Workshop
H.E.A.R. – Hearing Education and Awareness for Rockers
American Tinnitus Association – for musicians and music lovers
Hearing Loss from Headphones - High potential for hearing loss
Turn It to the Left – from the American Academy of Audiology
Binge Listening: Is exposure to leisure noise causing hearing loss in young Australians? [pdf] – report from Australian Hearing, National Acoustic Laboratories
Hearing Aids and Music: Interview with Marshall Chasin, AuD – from the American Academy of Audiology
Safe Listening Resources – from the National Hearing Conservation Association
OSHA Noise and Hearing Conservation - Occupational Health and Safety Administration
Decibels, dB Tutorial Includes:
Decibels, dB - the basicsDecibels levels tabledBm to dBW & power conversion chartdBm to watts and volts conversion chartdB, decibel online calculatorNepers
The deciBel, dB utilises a logarithmic scale based to compare two quantities. It is a convenient way of comparing two physical quantities like electrical power, intensity, or even current, or voltage.
The deciBel uses the base ten logarithms, i.e. those commonly used within mathematics. By using a logarithmic scale, the deciBel is able to compare quantities that may have vast ratios between them.
The deciBel, dB or deci-Bel is actually a tenth of a Bel - a unit that is seldom used.
The abbreviation for a deciBel is dB - the capital 'B' is used to denote the Bel as the fundamental unit.
DeciBel applications
The deciBel, dB is widely used in many applications. It is used within a wide variety of measurements in the engineering and scientific areas, particularly within electronics, acoustics and also within control theory.
Typically the deciBel, dB is used for defining amplifier gains, component losses (e.g. attenuators, feeders, mixers, etc), as well as a host of other measurements such as noise figure, signal to noise ratio, and many others.
In view of its logarithmic scale the deciBel is able to conveniently represent very large ratios in terms of manageable numbers as well as providing the ability to carry out multiplication of ratios by simple addition and subtraction.
The deciBel is widely used for measuring sound intensity or sound pressure level. For this the sound is referred to a pressure of 0.0002 microbars which equates to the standard for the threshold of hearing.
How the deciBel arrived
Since the beginning of telecommunications there has been the need to measure the levels of relative signal strengths so that loss and gain can be seen.
Original telecommunications systems used the loss that occurred in a mile of standard cable at a frequency of 800Hz.
However this was not a particularly satisfactory method of determining loss levels, or relative signal strengths and as radio and other electronics based applications started to need to use some form of standard unit for comparison, the Bel was introduced in the 1920s. This gained its name from the Scot, Alexander Graham Bell who was originally credited with the invention of the telephone.
With this system, one Bel equalled a tenfold increase in signal level. Once it was introduced the Bel was found to be too large for most suers and so the deciBel was used instead. This is now the standard that has been adopted universally.
DeciBel formula for power comparisons
The most basic form for deciBel calculations is a comparison of power levels. As might be expected it is ten times the logarithm of the output divided by the input. The factor ten is used because deciBels rather than Bels are used.
The deciBel formula or equation for power is given below:
Where:
Ndb is the ratio of the two power expressed in deciBels, dB
P2 is the output power level
P1 is the input power level
If the value of P2 is greater than P1, then the result is given as a gain, and expressed as a positive value, e.g. +10dB. Where there is a loss, the deciBel equation will return a negative value, e.g. -15dB. In this way a positive number of deciBels implies a gain, and where there is a negative sign it implies a loss.
Use our deciBel power calculator
DeciBel formulas for voltage & current
Although the deciBel is used primarily as comparison of power levels, deciBel current equations or deciBel voltage equations may also be used provided that the impedance levels are the same. In this way the voltage or current ratio can be related to the power level ratio.
When using voltage measurements it is easy to make the transformation of the deciBel formula because power = voltage squared upon the resistance:
And this can be expressed more simply as
Decibel Definition
Where:
Ndb is the ratio of the two power expressed in deciBels, dB
V2 is the output voltage level
V1 is the input voltage level
It is possible to undertake a similar transformation for the formula to use current. Power = current squared upon the resistance, and therefore the deciBel current equation becomes:
And this can be expressed more simply as
Where:
Ndb is the ratio of the two power expressed in deciBels, dB
I2 is the output current level
I1 is the input current level
Voltage & current deciBel formulas for different impedances
As a deciBel, dB is a comparison of two power or intensity levels, when current and voltage are used, the impedances for the measurements must be the same, otherwise this needs to be incorporated into the equations.
Decibel Definition
Where:
Ndb is the ratio of the two power expressed in deciBels, dB
V2 is the output voltage level
V1 is the input voltage level
Z2 is the output impedance
Z1 is the input impedance
In this way it is possible to calculate the power ratios in terms of deciBels between signals on points that have different impedance levels using either voltage or current measurements. This could be very useful when measuring power levels on an amplifier that may have widely different impedance levels at the input and output. If the voltage or current readings are taken then this formula can be used to provide the right power comparison in terms of deciBels.
DeciBel abbreviations
The deciBel is used in many areas from audio to radio frequency scenarios. In all of these it provides a very useful means of comparing two signals.
Decibel Apartments Seattle
Accordingly there are many variations onto e deciBel abbreviation and it may not always be obvious what they mean. A table of deciBel abbreviations is given below:
| DeciBel abbreviation | Meaning / usage |
|---|---|
| dBA | 'A' weighted sound pressure or sound intensity measurement. |
| dBc | Level of a signal with reference to the carrier being measured - normally used for giving the levels of spurious emissions and noise |
| dBd | Gain of an antenna with reference to a half wave dipole in free space |
| dBFS | Level with reference to full scale reading |
| dBi | Gain of an antenna with reference to an isotropic source, i.e. one that radiations equally in all directions. |
| dBm | Power level with reference to 1 mW |
| dBV | Level with reference to 1 volt |
| dBµV | Level with reference to 1 microvolt |
| dBW | Power level with reference to 1 watt |
The deciBel is widely used in many areas of electronics and sound measurement. It provides a very useful means of comparing different levels that may vary over a huge range. Being logarithmically based, the deciBel is able to accommodate variations of many orders of magnitude without getting lost in a huge number of zeros. In this way it is an ideal way of comparing different values.
Decibel Reader
Decibel Chart
More Basic Electronics Concepts & Tutorials:
VoltageCurrentPowerResistanceCapacitanceInductanceTransformersDecibel, dBKirchoff's LawsQ, quality factorRF noise
Return to Basic Electronics Concepts menu . . .