m - Refer to Milli
M - Refer to Mega
mA - Refer to Milliamps
Magnet - A device that can attract or repel pieces of iron or other magnetic material. Speaker magnets provide a stationary magnetic field so that when the coil produces magnetic energy, it is either repelled or attracted by the by the stationary magnet.
Magnetic Flux Density (B) -
Malfunction Indicator Light (MIL) - A dash mounted indicator of a re-occurring DTC in a vehicle with OBD-II. Also called the “Check Engine” light.
Mas - Acoustical equivalent to Mms.
Masking - Also referred to as auditory masking, occurs when the perception of one sound is affected by the presence of another sound. Masking in the frequency domain is known as simultaneous masking, frequency masking or spectral masking. Masking in the time domain is known as temporal masking or non-simultaneous masking.
Material Safety Data Sheet (MSDS) - The technical and safety information for any specific chemical(s) that OSHA requires a business to have on file in an accessible location.
Matrix Processing - A signal processing scheme in which standard 2 channel audio is processed with proprietary methods to derive a multi-channel output to achieve the effect of surround sound. Examples are Dolby Pro Logic IIx, Harman Logic 7, DTS NEO:6, etc.
Maximum Linear Excursion - Is defined as how far the cone of a speaker linearly travels from its resting position. In general lower frequency drivers or subwoofers are designed to move more air and have more excursion than those of higher frequency.
Maximum Power Rating - The maximum power rating is generally the maximum power threshold of any audio components output. Some manufacturers rate this measurement off of dynamic power or “perfect condition” burst power. This measurement is typically not the most accurate to go by when choosing audio components.
MDF - Refer to Medium Density Fiber Board
MEA - Refer to Mobile Electronics Association
Mechanical Energy - The energy of an object due to its motion or position; the sum of an object's kinetic energy and potential energy.
MECP - Refer to Mobile Electronics Certified Professional
Media Oriented Systems Transport (MOST) - A data transfer infotainment system, usually optical, engineered for the mobile environment in use on many modern OEM applications from 2002 and up. A high-speed multimedia network technology optimized by the automotive industry. It can be used for application inside or outside the car. The serial MOST bus uses a daisy-chain topology or ring topology and synchronous data communication to transport audio, video, voice and data signals via plastic optical fiber (POF) or electrical conductor physical layers.
Medium Density Fiber Board (MDF) - This is a wood made of many very small particles of wood which is compressed and heated, glued with a resin, and then cut to shape a full or partial sheet of wood. MDF is typically used to construct subwoofer enclosures and interior custom fabricated pieces.
Mega (M) - A prefix that means 106 (one million in the US). 1 MHz equals 1,000,000 Hertz.
Megahertz - 1,000,000 (1 million) cycles per second. Wireless mobile communications within North America generally occur in the 800 MHz, 900 MHz and 1900 MHz spectrum frequency bands.
Memory - The word most commonly used to refer to a system’s ability to retain specific information.
Metal Oxide Semiconductor Field Effect Transistor (MOSFET) - A type of field-effect transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals.
mH - Refer to Millihenries
MHz - Refer to Megahertz
Micro (µ) - A prefix that means 1/ 106 (one millionth in the US). 1 µV equals 1/1,000,000 of a volt.
Microfarads (mF) - A unit of capacitance, also represented with µF, equivalent to 0.000001 (10 to the -6th power) farad. The microfarad is a moderate unit of capacitance. In utility alternating-current (AC) and audio-frequency (AF) circuits, capacitors with values on the order of 1 mF or more are common.
Microprocessor - A semiconductor that can be programmed to perform a variety of tasks in many different electronic applications.
Midbass - High midrange or upper midrange cannot reach low, with a minimum range of about 60 Hz to 4 kHz. Midbass is typically dependent on the range capable of the midrange driver or subwoofer being used itself.
Midrange - The range of audio frequencies between 500 Hz and 2 kHz that when boosted, can increase prominent vocals in music. It can become very tinny or horn like if boosted too much in this range.
Midrange Driver - A loudspeaker specifically designed to reproduce the frequency in the middle of the audible bandwidth. Most musical energy lies in the midrange band. Midrange drivers are commonly seen to reach anywhere from 250 Hz to 2 kHz.
Midrange Frequency - This range is mostly dependent on the settings of the sound processing and the real world capability of the midrange driver or loudspeaker itself. Midrange can be produced anywhere from 250 Hz to 2 kHz.
MIL - Refer to Malfunction Indicator Light
Milli (m) - A prefix that means 1/ 103 (one thousandth). 1 mA equals 1/1,000 of an amp.
Milliamps (mA) - A unit of measurement of electrical current equal to 1/1000th of an ampere (0.001 amperes). The milliamps is the most common unit used when measuring quiescent (or “standby”) current draw.
Millihenries (mH) - A unit of inductance that is equal to one thousandth of a henry.
MIMO - Refer to Multiple Input, Multiple Output
MIN/MAX - A feature of a DMM in which the highest (MAX) or lowest (MIN) recorded value over the measurement period is displayed.
Mmd - Diaphragm mass, in grams.
Mms - The driver's effective mechanical mass (including air load), in kg. This parameter is the combination of the weight of the cone assembly plus the ‘driver radiation mass load’. The weight of the cone assembly is easy: it’s just the sum of the weight of the cone assembly components. The driver radiation mass load is the confusing part. In simple terminology, it is the weight of the air (the amount calculated in Vd) that the cone will have to push.
Mobile Electronics Association (MEA) - Over 1000 members strong, the mobile electronics (trade) association consists of manufacturers, retailers and service providers of automotive aftermarket technology products. Through its KnowledgeFest trade shows and conferences
it provides top-notch education, networking opportunities and business services designed to advance the professionalism and profitability for all of the industry's stakeholders. Its publication under the same name Mobile Electronics magazine, has more than 18,000 subscribers which also acknowledges the top retailers, installers and suppliers at its annual Industry Awards.
Mobile Electronics Certified Professional (MECP) - Is a certificate of achievement program in the United States that it is managed and administered by Consumer Electronics Association (CEA).
Mobile Telephone Switching Office (MTSO) - is the mobile equivalent to a PSTN Central Office. The MTSO contains the switching equipment or Mobile Switching Center (MSC) for routing mobile phone calls. Also contains the equipment for controlling the sites that are connected to the MSC.
Mobile Switching Center (MSC) - This is the centerpiece of network switching subsystem (NSS). The MSC is mostly associated with communications switching function, such as call setup, release, and routing.
Module - A term commonly used to describe a self-contained part or device that can perform a specific function.
Molex - is the vernacular term for a two-piece pin and socket interconnection. Pioneered by Molex Connector Company, the two-piece design became an early electronic standard.
Monaural - A sound recorded or reproduced in only one channel.
Monitor - With security this is a security system input that awaits a trigger or command from a sensor or vehicle electrical circuit. In auto video the video display device(s) used to view the video output generated by the video source. Typically an LCD screen in a mobile application.
Mono - Refer to Monaural
Motion Sensor - A sensor specifically designed to detect a gentle or sharp up and down or side-to-side motion of the vehicle.
MOSFET - Refer to Metal Oxide Semiconductor Field Effect Transistor
MOST - Refer to Media Oriented Systems Transport
Moving Picture Experts Group (MPEG) - A working group of authorities that was formed by ISO and IEC to set standards for audio and video compression and transmission.
MP3 (MPEG 1, Audio Layer 3) - A popular encoding and variable compression scheme for digital music. Must have a device with MP3 decoding for playback.
MPEG - Refer to Moving Picture Experts Group
Ms - The total moving mass of the loudspeaker cone.
MSC - Refer to Mobile Switching
MSDS - Refer to Material Safety Data Sheet
MTSO - Refer to Mobile Telephone Switching Office
Multimeter - A common term used to describe a VOM (voltage ohm meter). A multimeter usually has the ability to measure volts, resistance (ohms), and amperes or milliamperes.
Multi-path Interference - This is interference affects FM radio reception. FM waves travel in a straight line, so anything between you and the FM transmitter can cause multi-path interference. When FM signals bounce off buildings and other large objects, the tuner picks up the same signal more than once, at different times. This create "echoes" that confuse the tuner by mixing with the original signal.
Multiple Input, Multiple Output (MIMO) - The use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology. Note that the terms input and output refer to the radio channel carrying the signal, not to the consumer devices having antennas.
Multiplex (MUX) - A low current, multi function circuit found on many newer vehicles used in variety of functions previously supported by dedicated wires for each discrete function. MUX circuits use variable voltages or data messages on a single wire (or pair of wires) between a controller and a receiving device (such as a BCM) to other conditions. The goal is weight and cost savings for vehicle manufacturing. These systems are often low voltage (less than battery voltage) depending on the function tested. Also called “Multiplex” or “Variable Voltage” circuits.
Multi-Source - An audio/video system featuring multiple source units.
Multi-Zone - An audio/video system with multiple locations to listen and view the A/V entertainment.
Music - 1. an art of sound in time that expresses ideas and emotions in significant forms through the elements of rhythm, melody, harmony, and color. 2. the tones or sounds employed, occurring in single line (melody) or multiple lines (harmony), and sounded or to be sounded by one or more voices or instruments, or both. 3. musical work or compositions for singing or playing. 4. the written or printed score of a musical composition. 5. such scores collectively 6. any sweet, pleasing, or harmonious sounds or sound: the music of the waves 7. appreciation of or responsiveness to musical sounds or harmonies: Music was in his very soul.
Mute - Silent, attenuate.
MUX - Refer to Multiplex