Smiley face curve
Encyclopedia
Audio signal processing
Audio signal processing, sometimes referred to as audio processing, is the intentional alteration of auditory signals, or sound. As audio signals may be electronically represented in either digital or analog format, signal processing may occur in either domain...
, is a target frequency response
Frequency response
Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input...
curve characterized by boosted low and high frequencies coupled with reduced midrange frequency power. This curve is often attained by users employing a graphic equalizer which shows a graphic representation of a "smile" using its frequency band faders to describe a curve that sweeps upward at the left and right sides.
Smiley face curves have had a popular appeal with some car audio
Car audio
Car audio/video , auto radio, mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. While 12-volt audio and video systems are also used, marketed, or manufactured for marine, aviation, and buses, this article focuses on cars as the most common...
enthusiasts, disc jockey
Disc jockey
A disc jockey, also known as DJ, is a person who selects and plays recorded music for an audience. Originally, "disc" referred to phonograph records, not the later Compact Discs. Today, the term includes all forms of music playback, no matter the medium.There are several types of disc jockeys...
s, electric bass guitar players
Bass guitar
The bass guitar is a stringed instrument played primarily with the fingers or thumb , or by using a pick....
, home stereo owners and misguided live sound reinforcement system
Sound reinforcement system
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience...
operators.. Though the graphic equalizer was intended to tailor a system's response to match existing venue and performance conditions, the smiley face curve is often applied before the user has heard the system's frequency response.
Equal-loudness contour
The smiley face curve is roughly analogous to the frequency response of human hearing as charted in the equal-loudness contourEqual-loudness contour
An equal-loudness contour is a measure of sound pressure , over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon, and is arrived at by reference to equal-loudness contours...
, and has been compared to loudness compensation
Loudness compensation
Loudness compensation is a setting found on some hi-fi equipment and equalisers that increases the level of the high and low frequencies. This is intended to be used at low listening levels, to compensate for the fact that as the volume of audio decreases, the ear's lower sensitivity to extreme...
circuitry in that it increases the relative power of high and low frequencies without increasing the midrange power. In order for a sound system to be heard properly by humans, it should have an equal-loudness contour applied to it when it is performing at low sound pressure
Sound pressure
Sound pressure or acoustic pressure is the local pressure deviation from the ambient atmospheric pressure caused by a sound wave. Sound pressure can be measured using a microphone in air and a hydrophone in water...
levels, then the curve should gradually flatten out as it gets louder.
Usage
The origin of the smiley face curve has been attributed to the search for more bass and treble response from loudspeakerLoudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s that didn't extend as low or as high as desired, especially in the 1970s and 1980s. It has also been seen as either a useful or a detrimental tool for shaping the sound of a bass guitar.
Car audio
Many cars which have a graphic equalizer have been observed to have it set as a smiley face curve which emphasizes low and high frequencies. Misuse of the graphic equalizer is common, as many users know just enough to get themselves in trouble—large amounts of bass boost and treble boost can distort music and damage loudspeaker drivers. Ideally, the equalizer would be set once to compensate for the combination of the response of the speakers and the car's acoustic characteristics. A smiley face curve can indicate that a car's sound system is lacking both high and low frequency response or that the user didn't know what they were doing.Disc jockey
The smiley face curve has been called "popular" among disc jockeys who don't know that a graphic equalizer is a tool to compensate for room characteristics and to fight feedback frequencies.Bass guitar
Certain styles of electric bass playing, especially slappingSlapping
In music, the term slapping is often used to refer to two different playing techniques used on the double bass and on the bass guitar.-Double bass:...
, tend to augment the midrange frequencies. Various compensations have been developed to counteract excess midrange response in the instrument, including the use of amplifiers with a built-in smiley face curve and amplifiers that offer a handful of graphic equalizer filters so that the user can make the necessary adjustments when appropriate.
Gallien-Krueger
Gallien-Krueger
Gallien-Krueger, also referred to as 'GK' , is an instrument amplifier manufacturer. The company is based in Stockton, California, and was founded in 1968....
makes an instrument amplifier
Instrument amplifier
An instrument amplifier is an electronic amplifier that converts the often barely audible or purely electronic signal from musical instruments such as an electric guitar, an electric bass, or an electric keyboard into an electronic signal capable of driving a loudspeaker that can be heard by the...
that produces a classic smiley face curve in its default voicing. However, it includes tone controls that can be adjusted so that the amplifier is within 0.5 dB of a neutral, uncolored frequency response.
Some bass players decry the attenuation of midrange frequencies, holding that the midrange area centered on 500 Hz will make the bass instrumental line stand out more satisfyingly in the mix. University of Iowa
University of Iowa
The University of Iowa is a public state-supported research university located in Iowa City, Iowa, United States. It is the oldest public university in the state. The university is organized into eleven colleges granting undergraduate, graduate, and professional degrees...
professor and bass player Dan Berkowitz has observed that the smiley face curve as applied to bass played within a blues or R&B band can make it hard for bandmates to play off the bass line. Berkowitz recommends an upside down smile curve: a "frown" curve with its peak centered at 500–800 Hz.
Guitarists and bassists can choose to equalize their instrument with an effects pedal. Several products exist for this purpose such as a 10-band MXR-branded equalizer offered by Dunlop Manufacturing
Dunlop Manufacturing
Dunlop Manufacturing, Inc., known colloquially as Jim Dunlop, is a manufacturer of musical accessories based in Benicia, California. Originally founded in 1965 by Jim Dunlop, Sr., the company has grown from a small home operation to being a large manufacturer of music gear for over 40 years.- Way...
which includes instructions for a "Metal Distortion" setting that reduces 1,000 Hz, a midrange frequency, down to its maximum reduction point, with nearby frequencies reduced in the form of a mid scoop.
Live sound reinforcement
Isle of Wight Festival
The Isle of Wight Festival is a music festival which takes place every year on the Isle of Wight in England. It was originally held from 1968 to 1970. These original events were promoted and organised by the Foulk brothers under the banner of their company Fiery Creations Limited...
was to use "a bit of a 'smiley-face' EQ curve on the output" until he got a handle on a new band's mix, at which point he said "your balance comes together and you don't really need it."
On the other hand, the smiley face curve has been associated with tricks that fool the listener into thinking the speaker system is more capable than it really is, and it has been fingered as indicating that the user didn't bring a powerful enough sound system to meet the demands of the concert or that the user is inexperienced.
Kip Bradford of Expert Village emphasizes that the live sound engineer must not employ smiley face curves when setting up a sound reinforcement system. Bradford advises that the graphic equalizer should instead be used to "tune the system to the room", taking account of the combined frequency response of the room and the sound system to ensure that all audible frequencies have equal presence.
Manufacturer presets
Some audio equipment manufacturers have accommodated the user by engineering a smiley face curve into a product. dbx, Inc.Dbx, Inc.
dbx, Inc. is an American producer of professional audio recording equipment. It was founded by David E. Blackmer in 1971. The original company goal was: "To get closer to the realism of a live performance." Its early products were based on the concept of using decibel expansion which gave the...
offers several smiley face curve presets in their digital graphic equalizer product line called DriveRack. Jim Dunlop offers a direct box intended for bass players that includes a preset labeled "color" which engages a smiley face curve. Neither of these products prevent the user from adjusting the equalizer based on the sound that is actually heard rather than relying on a predetermined visual image.
Alpine Electronics
Alpine Electronics
is traditionally known as an aftermarket car audio and navigation systems manufacturer, famed for their high quality, premium in-car audio units commonly known as headunits. It is a subsidiary of Alps Electric Co. and its registered head office is in Tokyo, Japan. However its main offices, or the...
has offered for sale a product for car audio systems that works to counteract any smiley face curve that was applied to a car's factory OEM
Original Equipment Manufacturer
An original equipment manufacturer, or OEM, manufactures products or components that are purchased by a company and retailed under that purchasing company's brand name. OEM refers to the company that originally manufactured the product. When referring to automotive parts, OEM designates a...
sound system, along with an analysis feature that adjusts for road and vehicle noise. Empeg Car
Empeg Car
The Empeg Car is the first in-dash MP3 player developed. In 1998 a British company called Empeg was formed to build the unit, which shipped the following year....
, a digital media player, includes a "Loudness Control" feature that is described as adding a "smiley face" curve automatically" at low sound levels but which is used to lesser and lesser degrees as the car sound system's volume is increased. This describes an equal-loudness contour circuit.
See also
- Audio system measurementsAudio system measurementsAudio system measurements are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are...
- Audio effects
- Listener fatigue
- Smiling CurveSmiling CurveA smiling curve is an illustration of value-adding potentials of different components of the value chain in an IT-related manufacturing industry. The concept was first proposed by Stan Shih, the founder of Acer, an IT company headquartered in Taiwan, around 1992...
— a business concept that charts value relative to market position
External links
- Electronic Musician. Web Clips for May 2007. Focusrite Liquid Mix. Web Clip 7: Full drum mix through Fairchild 670 model, time constant 1, 10 dB of gain reduction.
- Electronic Musician. Web Clips for May 2007. Focusrite Liquid Mix. Web Clip 8: Full drum mix through Manley Massive Passive model, smiley-face curve (low/high boost, mid cut).