# DIY Audio & Video

## Sound Terms & Definitions

What is a Hz?

Hertz (Hz) simply means once per second. In audio terms, it is used to measure the frequency of a sound to characterize its pitch. A 100 Hz sound wave is a signal that repeats 100 times per second. Humans can normally hear sound between 20 Hz and 20,000 Hz.

What is a dB?

While the decibel (dB) can be used to measure the ratio between any 2 quantities, for the purpose of this site it is the measure of the ratio between two sound levels. The Decibel is a logarithmic scale that has no units. Usually loudness is measured in decibels because we perceive different levels of sound in a logarithmic scale. For example: the perceived increase from 50 dB to 60 dB is about the same as the increase from 90 dB to 95 dB. To standardize, dB are commonly specified in SPL (Sound Pressure Level). Here are some common SPL levels.

dB (SPL)Source
194Theoretical limit for a sound wave at 1 atmosphere environmental pressure
180Rocket engine at 30 meters
171Current SPL record for a IASCA Competition
120Threshold of pain
80Vacuum cleaner at 1 m
50Quiet restaurant inside
0Threshold of human hearing
• It takes an amplifier twice the power to produce an increase of +3 dB.
• It usually takes about 2-3 dB for a human to perceive a difference in a sound level.
• It takes +10 dB for a human to perceive a doubling of the sound level.
What is an octave?

An Octave is the difference between one musical note and another that has half or double the frequency. Ex: 1500 Hz and 3000 Hz are one octave apart. There are 9 octaves, with the first (Octave 0) being 32.7-61.7 Hz and the last (Octave 8) at 8372-15804 Hz. Since human hearing is 20-20,000 Hz, these octaves do not represent the full range of perceived sound. A good car or professional equalizer will have 31 bands from 20 - 20,000 (20 doubled 10 times is 20,480), with each band being 1/3 of an octave.

What are these terms used to describe speakers?
• Airy: Spacious. Open. Instruments sound like they are surrounded by a large reflective space full of air. Good reproduction of high-frequency reflections. High-frequency response extends to 15 or 20 kHz.
• Bassy: Emphasized low frequencies below about 200 Hz.
• Blanketed: Weak highs, as if a blanket were put over the speakers.
• Bloated: Excessive mid-bass around 250 Hz. Poorly damped low frequencies, low-frequency resonances. See tubby.
• Blurred: Poor transient response. Vague stereo imaging, not focused.
• Boomy: Excessive bass around 125 Hz. Poorly damped low frequencies or low-frequency resonances.
• Boxy: Having resonances as if the music were enclosed in a box. Sometimes an emphasis around 250 to 500 Hz.
• Breathy: Audible breath sounds in woodwinds and reeds such as flute or sax. Good response in the upper-mids or highs.
• Bright: High-frequency emphasis. Harmonics are strong relative to fundamentals.
• Chesty: The vocalist sounds like their chest is too big. A bump in the low-frequency response around 125 to 250 Hz.
• Clear: See Transparent.
• Colored: Having timbres that are not true to life. Non-flat response, peaks or dips.
• Crisp: Extended high-frequency response, especially with cymbals.
• Dark: Opposite of bright. Weak high frequencies.
• Delicate: High frequencies extending to 15 or 20 kHz without peaks.
• Depth: A sense of distance (near to far) of different instruments.
• Detailed: Easy to hear tiny details in the music; articulate. Adequate high-frequency response, sharp transient response.
• Dull: See dark.
• Edgy: Too much high frequencies. Trebly. Harmonics are too strong relative to the fundamentals. Distorted, having unwanted harmonics that add an edge or raspiness.
• Fat: See Full and Warm. Or, spatially diffuse - a sound is panned to one channel, delayed, and then the delayed sound is panned to the other channel. Or, slightly distorted with analog tape distortion or tube distortion.
• Full: Strong fundamentals relative to harmonics. Good low-frequency response, not necessarily extended, but with adequate level around 100 to 300 Hz. Male voices are full around 125 Hz; female voices and violins are full around 250 Hz; sax is full around 250 to 400 Hz. Opposite of thin.
• Gentle: Opposite of edgy. The harmonics - highs and upper mids - are not exaggerated, or may even be weak.
• Grainy: The music sounds like it is segmented into little grains, rather than flowing in one continuous piece. Not liquid or fluid. Suffering from harmonic or I.M. distortion. Some early A/D converters sounded grainy, as do current ones of inferior design. Powdery is finer than grainy.
• Grungy: Lots of harmonic or I.M. distortion.
• Hard: Too much upper midrange, usually around 3 kHz. Or, good transient response, as if the sound is hitting you hard.
• Harsh: Too much upper midrange. Peaks in the frequency response between 2 and 6 kHz. Or, excessive phase shift in a digital recorder's lowpass filter.
• Honky: Like cupping your hands around your mouth. A bump in the response around 500 to 700 Hz.
• Mellow: Reduced high frequencies, not edgy.
• Muddy: Not clear. Weak harmonics, smeared time response, I.M. distortion.
• Muffled: Sounds like it is covered with a blanket. Weak highs or weak upper mids.
• Nasal: Honky, a bump in the response around 600 Hz.
• Piercing: Strident, hard on the ears, screechy. Having sharp, narrow peaks in the response around 3 to 10 kHz.
• Presence: A sense that the instrument in present in the listening room. Synonyms are edge, punch, detail, closeness and clarity. Adequate or emphasized response around 5 kHz for most instruments, or around 2 to 5 kHz for kick drum and bass.
• Puffy: A bump in the response around 500 Hz.
• Punchy: Good reproduction of dynamics. Good transient response, with strong impact. Sometimes a bump around 5 kHz or 200 Hz.
• Rich: See Full. Also, having euphonic distortion made of even-order harmonics.
• Round: High-frequency rolloff or dip. Not edgy.
• Sibilant: "Essy" Exaggerated "s" and "sh" sounds in singing, caused by a rise in the response around 6 to 10 kHz.
• Sizzly: See Sibilant. Also, too much highs on cymbals.
• Smeared: Lacking detail. Poor transient response, too much leakage between microphones. Poorly focused images.
• Smooth: Easy on the ears, not harsh. Flat frequency response, especially in the midrange. Lack of peaks and dips in the response.
• Spacious: Conveying a sense of space, ambiance, or room around the instruments. Stereo reverb. Early reflections.
• Steely: Emphasized upper mids around 3 to 6 kHz. Peaky, nonflat high-frequency response. See Harsh, Edgy.
• Strident: See Harsh, Edgy.
• Sweet: Not strident or piercing. Delicate. Flat high-frequency response, low distortion. Lack of peaks in the response. Highs are extended to 15 or 20 kHz, but they are not bumped up. Often used when referring to cymbals, percussion, strings, and sibilant sounds.
• Telephone-like: See Tinny.
• Thin: Fundamentals are weak relative to harmonics.
• Tight: Good low-frequency transient response and detail.
• Tinny: Narrowband, weak lows, peaky mids. The music sounds like it is coming through a telephone or tin can.
• Transparent: Easy to hear into the music, detailed, clear, not muddy. Wide flat frequency response, sharp time response, very low distortion and noise.
• Tubby: Having low-frequency resonances as if you're singing in a bathtub. See bloated.
• Veiled: Like a silk veil is over the speakers. Slight noise or distortion or slightly weak high frequencies. Not transparent.
• Warm: Good bass, adequate low frequencies, adequate fundamentals relative to harmonics. Not thin. Also excessive bass or midbass. Also, pleasantly spacious, with adequate reverberation at low frequencies. Also see Rich, Round. Warm highs means sweet highs.
• Weighty: Good low-frequency response below about 50 Hz. Suggesting an object of great weight or power, like a diesel locomotive.