Harmonic - The overtones and undertones that define the acoustic difference between two sounds with the same fundamental frequency.
Harness - The universal name for a bundle or loom of wires that compose the wiring for a system.
Hands Free Profile (HFP) - The HFP allows more control and access, than Headset Profile (HF), to mobile phones via Bluetooth. The aftermarket products have many benefits, one being the flexibility of display and control options as well as the amount of phones that can pair to a single vehicle kit, as well as software upgrades or updates that may ensure future compatibility with new devices or profiles.
HDCP - Refer to High-bandwidth Digital Content Protection
Headroom – The difference between the highest level present in an audio signal and the maximum level an audio device can handle without noticeable distortion. A greater amount of headroom reduces the chances for unwanted distortion in an audio system.
Headset Profile (HP) – The most basic Bluetooth user profile. This profile allows the call to be accepted or terminated (hung up) and may also include a volume control.
Heat Sink - A heat sink (commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or mechanical device to a fluid medium, often air or liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device’s temperature at optimal levels.
Heat Shrink - a shrinkable plastic tubing used to insulate wires, providing abrasion resistance and environmental protection for stranded and solid wire conductors, connections, joints and terminals in electrical work.
Henries (Henry/Hy) - The measurement for inductance. Coils (low pass filters) are measured in millihenries as in 6.4 mHy (6.4 millihenries).
Hertz (Hz) - The unit of frequency within a specific period, such as alternating or pulsing current; 1 Hz = 1 cycle per second.
HFP - Refer to Hands Free Profile
HID Bulb - Refer to High Intensity Discharge
High-bandwidth Digital Content Protection (HDCP) - This is a specification developed by Intel to address digital rights management. HDCP is used with HDTV signals over DVI (optional) and HDMI connections (mandatory) to prevent unauthorized duplication of copywritten material by inhibiting the unauthorized distribution of digital video material through copying. It consists of data "keys" incorporated in the digital content together with proprietary encryption (scrambling) circuitry and software in the various video components (tuner, TV, DVD player, etc.) that handle HDTV.
High Definition Multimedia Interface (HDMI) - Now up to version 1.3, this digital video interface allows high definition video (up to and in excess of 1080p/60) and audio (up to 8 lossless channels) to be transmitted over a single cable. Except for some proprietary solutions (such as Impact Acoustics RapidRun Digital cables) HDMI cannot be terminate din the field and must be purchased in the correct lengths. Cables can be made of copper (limited to ~30 feet without electronic signal boost and equalization) or fiber optic, with the latter able to reach almost unlimited distances.
High Frequency - This refers to radio frequencies in the 3-30 MHz band. In audio it usually refers to frequencies in the 5-20 kHz band. Also see "Highs."
High Intensity Discharge (HID) - A type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. HID lamps, or bulbs are generally demand more power and often need what is referred to as a ballast to amplify the input voltage of the bulb. These types of bulbs are very sensitive and are often recommended to be handled wearing clean gloves to avoid it being exposed to the oils on human skin.
High Output Alternator - For the unit to qualify as a high output, it needs to provide more amperage than the factory unit that it replaced. This means there is a big difference between a high output unit which provides 100A at idle speeds and a water-cooled unit that provides upwards of 350A.
High Pass Filter (HPF) - A network of components which attenuate all frequencies below a predetermined frequency selected by the designer. Frequencies above cutoff are passed without any effect.
High Resolution Audio (Hi-Res) - Also referred to as High-definition audio or HD audio, is a technical and marketing term used by some recorded-music retailers and high-fidelity sound reproduction equipment vendors. It refers to higher than 44.1 kHz sample rate and/or higher than 16-bit linear bit depth.
Highs - Or tweeters as they are also called, typically play high range frequencies. The highs are frequencies typically between 5 kHz and 20 kHz.
Hiss - To make or emit a sharp sound like that of the letter “S” prolonged, as a snake does, or as steam does when forced under pressure through a small opening.
HDMI - Refer to High Definition Multimedia Interface
Horn - In audio this refers to a loading deice when part of a bass enclosure, or a directional device when used with a high-frequency driver or compression driver. In security this refers to the built-in factory horn in the vehicle. Factory horns can be of the diaphragm type, voice coil type, or air-pump driven type (air horn). All types of horns can be interfaced to a security system.
Horsepower - A unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second. This unit has been widely replaced by the watt in scientific usage; one horsepower is equal to 756 watts.
HP - Refer to Headset Profile
HPF - Refer to High Pass Filter
HPSA+ - Refer to Evolved High-Speed Packet Access
Hum - An audio noise that has a steady low frequency pitch. To utter a sound like a long “M”. To make a buzzing noise of a flying insect. To make musical tones with closed lips.
Hy - Refer to Henries
Hz - Refer to Hertz