Title: Monaural
Content:  Instances of both "merged stereo" and "mirrored mono" can occur when the stereo channels are merged to a mono system with stereo headphone compatibility or when a mono system has "twin speakers" (or "pseudo-stereo"). Other applications that involve mirrored mono with merged stereo occur when MONO is available as an internal feature of a device that can toggle between STEREO and MONO, for instance many FM radios are capable of toggling between MONO and STEREO in a way where stereo can both MERGE into mono, and then MIRROR between both stereo speakers. This tactic can also be used on other devices, of which computer software and some video games will have a feature that will allow STEREO or MONO for the soundtrack, in which sometimes this can facilitate MERGING stereo internally to spare one from using a Y adapter with LEFT and RIGHT RCA plugs when using mono equipment, such as guitar amplifiers.
Title: FM broadcasting
Content:  switching technique to recover the left and right channels. In addition, for a given RF level at the receiver, the signal-to-noise ratio and multipath distortion for the stereo signal will be worse than for the mono receiver. For this reason many stereo FM receivers include a stereo/mono switch to allow listening in mono when reception conditions are less than ideal, and most car radios are arranged to reduce the separation as the signal-to-noise ratio worsens, eventually going to mono while still indicating a stereo signal is being received. As with monaural transmission, it is normal practice to apply pre-emphasis to the left and right channels before 
Title: Monaural
Content:  Sometimes mono sound or monaural can simply refer to a merged pair of stereo channels - also known as "collapsed stereo" or "folded-down stereo". Over time some devices have used mono sound amplification circuitry with two or more speakers since it can cut the cost of the hardware. Some consumer electronics with stereo RCA outputs have a microswitch in the red RCA output (i.e., the right stereo channel) that disables merging of stereo sound into the white (left stereo channel) RCA output. Common devices with this are VCRs, DVD/Blu-ray players, information appliances, set-top boxes, and the like. Video game consoles sometimes have male RCA ends of cables with a proprietary multi-A/V plug on the other end, which prevents automatic stereo merging unless adapters are used. Disadvantages of merged stereo involve phase cancellations that may 
Title: Monaural
Content:  like stereo ones, typically use multiple microphones fed into multiple channels on a recording console, but each channel is "panned" to the center. In the final stage, the various center-panned signal paths are usually mixed down to two identical tracks, which, because they are identical, are perceived upon playback as representing a single unified signal at a single place in the soundstage. In some cases, multitrack sources are mixed to a one-track tape, thus becoming one signal. In the mastering stage, particularly in the days of mono records, the one- or two-track mono master tape was then transferred to a one-track lathe used to produce a master disc intended to be used in the pressing of 
Title: Monaural
Content:  the effect of muffling the final sound output. If channels are merged after being sent through a power amplifier but before being connected to a loudspeaker, it places more stress on the loudspeaker. It has usually been the practice in recording studios to make separate mixes for mono recordings (rather than folded-down stereo-to-mono), so that the final mono master will avoid the pitfalls of collapsed stereo. In video games, merging stereo to mono sound prevents player from discerning what direction distant SFX are coming from, and reverse stereo has a similar setback too. Having an array of loudspeakers connected to their own amplifier outputs can mitigate issues with the electrical load for a single loudspeaker coil and allow the listener to perceive an "image" of sound in the free space between the speakers.
Title: Stereophonic sound
Content:  In the course of restoration or remastering of monophonic records, various techniques of "pseudo-stereo", "quasi-stereo", or "rechanneled stereo" have been used to create the impression that the sound was originally recorded in stereo. These techniques first involved hardware methods (see Duophonic) or, more recently, a combination of hardware and software. Multitrack Studio, from Bremmers Audio Design (The Netherlands), uses special filters to achieve a pseudo-stereo effect: the "shelve" filter directs low frequencies to the left channel and high frequencies to the right channel, and the comb filter adds a small delay in signal timing between the two channels, a delay barely noticeable by ear, but contributing to an effect of "widening" original "flattiness" of mono recording. According to Sweetwater Sound, "As the cost of processing technology dropped manufacturers were able to include dual processors in equipment. 
Title: Microphone practice
Content:  left to right, there may be some loss of high frequencies when played back in mono, so they are often separated vertically. This only causes problems with sound from above or below the height of the microphones. ; The M/S technique is ideal for mono compatibility, since summing Left+Right just gives the Mid signal back. If a stereo signal is to be reproduced in mono, out-of-phase parts of the signal will cancel, which may cause the unwanted reduction or loss of some parts of the signal. This can be an important factor in choosing which technique to use. The equipment for the techniques also varies from the bulky 
Title: Monaural
Content:  Monaural or monophonic sound reproduction (often shortened to mono) is sound intended to be heard as if it were emanating from one position. This contrasts with stereophonic sound or stereo, which uses two separate audio channels to reproduce sound from two microphones on the right and left side, which is reproduced with two separate loudspeakers to give a sense of the direction of sound sources. In mono, only one loudspeaker is necessary, but, when played through multiple loudspeakers or headphones, identical signals are fed to each speaker, resulting in the perception of one-channel sound "imaging" in one sonic space between the speakers (provided that the speakers are set up in a proper symmetrical critical-listening placement). Monaural 
Title: Monaural
Content:  Mirrored mono sound is the opposite of merged stereo, since it can be a case where media with mono sound that stereo playback devices automatically mirror it with are played on both channels of the receiver. It can also mean having a mono input mixed down to stereo amplification circuitry, or a mono system with a headphone output compatible with stereo headphones. An example of an application where both merged stereo and mirror mono apply is when a compact audio cassette respectively plays back "summed" stereo channels on a mono reading head, and when a compact cassette recorded with mono sound is played back with a stereo tape head. Other instances of "mirrored mono" also include using the right stereo channel in lieu of a "left" one (or vice versa) where both channels are wired to mirror only one.
Title: Haeco-CSG
Content:  The Haeco-CSG process was designed to make stereophonic vinyl LP records compatible with mono playback equipment. These recordings were intended to make the two-channel stereo mix automatically "fold-down" properly to a single mono channel. The reason for the process is the compatibility issue between stereophonic and monaural recordings: information which is identical on both the left and right channels of a stereophonic mix sounds too loud when played back on mono AM and FM radio stations and phonographs. When the left and right channels are summed together, any musical parts that are common to both channels combine to be 6 decibels louder than they are in the same mix when played in stereo 

Question: converting stereo signal to mono signal is called?
Answer: Panning.