Speaker spec sheets are full of short terms and units. This glossary explains the ones you are most likely to meet when you read about Bluetooth, bookshelf, floorstanding, outdoor, ceiling and marine speakers.
The definitions are general and neutral. They are written by the Ebservant Editorial Team from published technical information. Always check the manufacturer’s own documentation for how a specific product uses a term.
- Active speaker
- An active speaker has an amplifier built into its cabinet. It needs a power connection plus an audio source. Many Bluetooth speakers are active designs.
- Amplifier
- An amplifier increases a weak audio signal so it can move a speaker’s drivers. It can be built into the speaker or be a separate component. Its power and quality affect loudness and clarity.
- Bass reflex port
- A bass reflex port is an opening in the cabinet that lets air move in and out. It reinforces low frequencies at certain pitches. Ported designs can produce more bass from a given cabinet size.
- Bluetooth codec
- A codec is the method used to compress and send audio over Bluetooth. Common examples include SBC, AAC and aptX. Both the phone and the speaker must support a codec for it to be used.
- Bookshelf speaker
- A bookshelf speaker is a compact speaker meant for a shelf, desk or stand. It is smaller than a floorstanding model. Many bookshelf speakers are used in pairs for stereo sound.
- Ceiling speaker
- A ceiling speaker mounts into or onto a ceiling and points sound down into the room. It is often chosen when floor space is limited. Installation usually involves cutting a hole and running speaker wire.
- Crossover
- A crossover divides the audio signal into frequency ranges. Each range goes to the driver best suited to reproduce it. It may be passive circuitry inside the speaker or part of an active system.
- Decibel (dB)
- The decibel is a unit that expresses sound level or a ratio between two levels. It is logarithmic, so a small change in number can mean a noticeable change in loudness. Speaker sensitivity is given in decibels.
- Driver
- A driver is the part that turns an electrical signal into sound by moving air. Woofers, midrange drivers and tweeters are all drivers. Most speakers use more than one.
- Enclosure
- The enclosure is the cabinet that holds the drivers. Its size, material and shape affect how the speaker sounds. Sealed and ported cabinets are two common types.
- Floorstanding speaker
- A floorstanding speaker is a tall cabinet that sits on the floor. Its larger enclosure can hold bigger drivers. It usually needs more space than a bookshelf model.
- Frequency response
- Frequency response is the range of pitches a speaker can reproduce, such as 50 Hz to 20 kHz. It is often listed with a tolerance in decibels. The figure alone does not describe how the speaker sounds.
- Hertz (Hz)
- Hertz measures how many cycles per second a sound wave completes. Low numbers mean low pitch and high numbers mean high pitch. The range of human hearing is commonly given as about 20 Hz to 20,000 Hz.
- Impedance
- Impedance is the electrical resistance a speaker presents to an amplifier, measured in ohms. Common values are 4, 6 and 8 ohms. The amplifier should be rated to work with the speaker’s impedance.
- IP rating
- An IP rating describes how well a product resists dust and water. It has two digits, one for solids and one for liquids. A higher digit means more protection in that category.
- Marine speaker
- A marine speaker is built for boats and other wet environments. Makers design them to resist water, salt and sunlight. The exact protection depends on the product’s specifications.
- Outdoor speaker
- An outdoor speaker is made to be used outside, such as on a patio or deck. It is designed to withstand weather to a stated degree. Look for the maker’s rating rather than assuming full protection.
- Passive speaker
- A passive speaker has no built-in amplifier. It must be connected to a separate amplifier or receiver with speaker wire. Many bookshelf and floorstanding speakers are passive.
- Power handling
- Power handling is the amount of amplifier power a speaker is rated to accept, in watts. It is often given as continuous and peak figures. It is not the same as how loud the speaker plays.
- Sealed enclosure
- A sealed enclosure is an airtight cabinet with no port. It tends to have a more controlled bass response. It may need more amplifier power to reach the same bass level as a ported design.
- Sensitivity
- Sensitivity states how loud a speaker plays with a given input, usually measured at one watt from one meter. A higher number means it plays louder with the same power. It is shown in decibels.
- Subwoofer
- A subwoofer is a speaker built only for the lowest frequencies. It adds bass that smaller speakers can’t produce. It can be active or passive, and it is often paired with a stereo pair.
- Total harmonic distortion
- Total harmonic distortion, or THD, measures unwanted tones a device adds to a signal. It is given as a percentage. Lower values mean less added distortion under the stated test conditions.
- Tweeter
- A tweeter is the small driver that handles high frequencies. It produces the details and sparkle in music. Tweeters are often shaped like a dome or a horn.
- Woofer
- A woofer is a driver designed for low frequencies. It is larger than a tweeter. In two-way speakers, the woofer often covers the bass and midrange.
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