Sidetone
Encyclopedia
Sidetone is audible feedback to someone who is speaking. The term is most used in telecommunication
contexts.
, sidetone is the effect of sound that is picked up by the telephone's mouthpiece and in real-time introduced at a low level into the earpiece of the same handset, acting as controlled feedback
. Sidetone in 19th century telephones varied until the carbon transmitter
was used, which produced a distinct sidetone that discouraged speaking loudly enough, and occasionally so loud as to throw the instrument into uncontrolled oscillation or "howling". Sidetone is inactive when phones of any kind are running in speakerphone mode, due to perpetual and almost immediate feedback looping. Anti-sidetone circuitry incorporating the principle of the hybrid coil
brought sidetone under control in the early 20th century, leaving enough to assure the user that the phone is really working, and allowing the use of a unitized telephone handset. In cellular technologies, one of the many benefits of sidetone-enabled phones is that a user knows a call has been dropped or ended if he or she no longer hears sidetone.
Usability studies done at RIM (manufacturers of BlackBerry smartphones), LG
and Motorola
have demonstrated that a lack of sidetone has a tendency to make the user of a phone or cellular handset characterize it as dead or disconnected. In the same battery of tests, it was found that the presence of sidetone prevents users from needing to examine the device's display to determine if a call is still active. First introduced in the StarTAC
handset, almost all cellular handsets manufactured by Motorola have sidetone, though its level of feedback ajustable by the user. Too much sidetone causes users to hear their own voice loudly which is why it is not standard on all cellular handsets and leaves the decision to incorporate sidetone up to the manufacturers. In usability studies prior to the launch of Apple's first-generation iPhone
, users were quoted as feeling uncomfortable when the amount of sidetone is too high and will lower the level of their voice unnecessarily. Currently, the iPhone does not have +6% - +9% sidetone, while almost all Android, Palm, and Windows mobile devices do.
Digital telephones lack the mechanical acoustics
and circuitry that used physical wiring to produce sidetone in older landline
phones, so digital phones include electronic circuitry, software and firmware
to reproduce sidetone. Many cell phones do not provide adequate sidetone despite general agreement among leading industrial design & usability experts who claim it is an important feature in cell phones, perhaps even more so than for land-lines because of the less predictable acoustics one will encounter while using a cellular phone.
Almost all land-line (wired and wireless) phones have employed sidetone, so naturally it was an expected convention for cellular telephony but is not standard by any means. Usability experts believe that lack of adequate sidetone causes some people to shout or speak too loudly when using a cell phone (this behavior is often referred to as "cell yell").
Sidetone is valuable for the hearing impaired. The amount of sidetone typically found on land-lines is 8%, and is 4% for cellular phones. Sidetone can be, and often is, amplified for land-line phones for the hearing impaired. In VOIP technologies such as Skype
, sidetone has been experimented with but has not been formally adopted by software or hardware & accessories creators. Several software packages and wiring workarounds have been developed that replicate sidetone, but feedback looping remains a problem.
(WT) and amateur radio
, sidetone is the audible indication of a CW
signal as the operator sends Morse Code
. Like the telephony
definition of sidetone, it acts as feedback to the operator that what they are sending is what is intended.
It is designed to mimic the tone generated by a typical radio receiver when a CW
signal is converted to the intermediate frequency
(IF), then mixed with the BFO frequency to generate a difference frequency, which is audible over the radio receiver loudspeaker or headphones.
Sidetone is also used on voice radio equipment to give the radio operator confidence that they are transmitting over the radio. The sidetone audio is typically derived from the transmit audio circuitry.
, or MC for a public event may otherwise be able to hear their own voice in the delayed output from the loudspeakers, they may opt to use a headset which provides instant sidetone of their own voice, thus removing the distracting effect of greatly delayed feedback from the loudspeakers.
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
contexts.
Telephony
In telephonyTelephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, sidetone is the effect of sound that is picked up by the telephone's mouthpiece and in real-time introduced at a low level into the earpiece of the same handset, acting as controlled feedback
Feedback
Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...
. Sidetone in 19th century telephones varied until the carbon transmitter
Carbon microphone
The carbon microphone, also known as a carbon button microphone or a carbon transmitter, is a sound-to-electrical signal transducer consisting of two metal plates separated by granules of carbon. One plate faces outward and acts as a diaphragm...
was used, which produced a distinct sidetone that discouraged speaking loudly enough, and occasionally so loud as to throw the instrument into uncontrolled oscillation or "howling". Sidetone is inactive when phones of any kind are running in speakerphone mode, due to perpetual and almost immediate feedback looping. Anti-sidetone circuitry incorporating the principle of the hybrid coil
Hybrid coil
A hybrid coil is a transformer that has three windings, and which is designed to be configured as a circuit having four branches, that are conjugate in pairs....
brought sidetone under control in the early 20th century, leaving enough to assure the user that the phone is really working, and allowing the use of a unitized telephone handset. In cellular technologies, one of the many benefits of sidetone-enabled phones is that a user knows a call has been dropped or ended if he or she no longer hears sidetone.
Usability studies done at RIM (manufacturers of BlackBerry smartphones), LG
LG Electronics
LG Electronics is a global electronics and telecommunications company headquartered in Yeouido, Seoul, South Korea. The company operates its business through five divisions: mobile communications, home entertainment, home appliance, air conditioning and business solution...
and Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
have demonstrated that a lack of sidetone has a tendency to make the user of a phone or cellular handset characterize it as dead or disconnected. In the same battery of tests, it was found that the presence of sidetone prevents users from needing to examine the device's display to determine if a call is still active. First introduced in the StarTAC
Motorola StarTAC
The Motorola StarTAC is a clamshell mobile phone manufactured by Motorola. It was released on 3 January 1996, being the first ever clamshell/flip mobile phone. The StarTAC is the successor of the MicroTAC, a semi-clamshell design that had been launched in 1989. Whereas the MicroTAC's shell folded...
handset, almost all cellular handsets manufactured by Motorola have sidetone, though its level of feedback ajustable by the user. Too much sidetone causes users to hear their own voice loudly which is why it is not standard on all cellular handsets and leaves the decision to incorporate sidetone up to the manufacturers. In usability studies prior to the launch of Apple's first-generation iPhone
IPhone
The iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...
, users were quoted as feeling uncomfortable when the amount of sidetone is too high and will lower the level of their voice unnecessarily. Currently, the iPhone does not have +6% - +9% sidetone, while almost all Android, Palm, and Windows mobile devices do.
Digital telephones lack the mechanical acoustics
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
and circuitry that used physical wiring to produce sidetone in older landline
Two-wire circuit
In telecommunication, a two-wire circuit is characterized by supporting transmission in two directions simultaneously, as opposed to four-wire circuits, which have separate pairs for transmit and receive. In either case they are twisted pairs. Telephone lines are almost all two wire, while trunks...
phones, so digital phones include electronic circuitry, software and firmware
Firmware
In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices...
to reproduce sidetone. Many cell phones do not provide adequate sidetone despite general agreement among leading industrial design & usability experts who claim it is an important feature in cell phones, perhaps even more so than for land-lines because of the less predictable acoustics one will encounter while using a cellular phone.
Almost all land-line (wired and wireless) phones have employed sidetone, so naturally it was an expected convention for cellular telephony but is not standard by any means. Usability experts believe that lack of adequate sidetone causes some people to shout or speak too loudly when using a cell phone (this behavior is often referred to as "cell yell").
Sidetone is valuable for the hearing impaired. The amount of sidetone typically found on land-lines is 8%, and is 4% for cellular phones. Sidetone can be, and often is, amplified for land-line phones for the hearing impaired. In VOIP technologies such as Skype
Skype
Skype is a software application that allows users to make voice and video calls and chat over the Internet. Calls to other users within the Skype service are free, while calls to both traditional landline telephones and mobile phones can be made for a fee using a debit-based user account system...
, sidetone has been experimented with but has not been formally adopted by software or hardware & accessories creators. Several software packages and wiring workarounds have been developed that replicate sidetone, but feedback looping remains a problem.
Radiotelegraphy
In wireless telegraphyWireless telegraphy
Wireless telegraphy is a historical term used today to apply to early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio before the term radio came into use....
(WT) and amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
, sidetone is the audible indication of a CW
Continuous wave
A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
signal as the operator sends Morse Code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
. Like the telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
definition of sidetone, it acts as feedback to the operator that what they are sending is what is intended.
It is designed to mimic the tone generated by a typical radio receiver when a CW
Continuous wave
A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
signal is converted to the intermediate frequency
Intermediate frequency
In communications and electronic engineering, an intermediate frequency is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called...
(IF), then mixed with the BFO frequency to generate a difference frequency, which is audible over the radio receiver loudspeaker or headphones.
Sidetone is also used on voice radio equipment to give the radio operator confidence that they are transmitting over the radio. The sidetone audio is typically derived from the transmit audio circuitry.
Public address systems
When a commentator, announcerAnnouncer
An announcer is a presenter who makes "announcements" in an audio medium or a physical location.-Television and other media:Some announcers work in television production , radio or filmmaking, usually providing narrations, news updates, station identification, or an introduction of a product in...
, or MC for a public event may otherwise be able to hear their own voice in the delayed output from the loudspeakers, they may opt to use a headset which provides instant sidetone of their own voice, thus removing the distracting effect of greatly delayed feedback from the loudspeakers.
See also
- TelephoneTelephoneThe telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
- Beat Frequency Oscillator
- Continuous waveContinuous waveA continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
- Echo cancellationEcho cancellation'The term echo cancellation is used in telephony to describe the process of removing echo from a voice communication in order to improve voice quality on a telephone call...