Audio/Acoustics

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Revision as of 14:53, 11 May 2008

Note
Most of this page is automatically translated from german. Alphabetical sort order is not correct.

Jump to: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Contents

A

decay time

Decay time (ger. Abfallzeit) is the time that elapses in which the sound pressure level (or any other characteristic given) by a value drops to another, both values, the starting value and the target must be explicitly set out. A common unit for the description of the decay time of sound is per second decibels (dB / s).

  • Note 1: The decay constant characterizes the exponential course of the sound decay after the sound source was stopped (unit: s-1).
  • Note 2: If p0 the effective pressure at time t = 0 and p(t) the effective pressure at time t, and both follow the relationship: p(t) = p0 * ek * t then k is the decay constant.
absolute hearing

see #absolute pitch

absolute pitch

Absolute pitch (ger. Absolutes Gehör) is a person's ability to pitch (identify) any clear sine tone frequency (musical note) without an external reference.

  • Remark: The identification of emerging permissible error variance has to be specified (see Perfect pitch).
  • Remark: Mostly a musical note is identified not a frequency value.
adaptation

Adaptation (ger. Adaption) ...

Adaptive psychophysical method

A psychophysical adaptive method (ger. adaptive psychophysikalische Methode) is primarily for the determination of thresholds set up for this procedure is the charm size depending on the response of the subject to the previously stated charm. The size can be a stimulus) under the direct control of the subject, or b) it is the investigator adjusted depending on the number of previously delivered right or wrong answers.

chord

A chord (Engl. chord) consists of three or more simultaneously erklingenden notes. In general use, the individual components three or four half away (small, large third; triad, Tetrachord, Sept chord).

  • Note: The harmony without taking into account the intervals is called cluster [Moorer, 1975].
chord progress exceeded

Fort chord exceeded (Engl. chord progression) is a sequence of chords, a Fort homorhythmische misuse of sounds, from complex tones are compounded (musically: notes). [PAR]

chord fundamental

A chord fundamental (English bass fondamentale) is a physically non-existent, hinzugedachter tone in Baßlage, see Virtual pitch. [TER]

chord class

Under a chord chords class (English class chord) is those whose grades only by the Chroma (pitch-class).

  • Note: examples of a chord class: CEG, c2-e2-g2 or g1-e2-c3. The chords can be inverted or doubled (see Stimmakkord? .. Chord mood?).
chord final position

Final chord position (Engl. chord close-position), the mood is a chord class with the lowest and the highest grade less than an octave away. [PAR]

Acoustics
  1. Acoustics (Engl. Acoustics) is the science of sound, including its production, transmission and effects.
  2. The acoustics of a space is the totality of those properties that a particular sound field characteristics, and thus a sensation cause hearing.
acoustically

The qualifying word acoustic properties (Engl. acoustic, acoustical) means producing, arising from, as updated by, in relation to, or associated with sound, in short, the sound on. In English acoustic used in the technical sense, if the term should refer to something that is compatible with the properties, size or physical characteristics of the sound waves associated. Acoustical is needed if the qualifying term is not explicitly such properties, size or physical characteristics. The distinction between acoustic and acoustical is not in German.

  • Note 1: Examples of the name are acoustic physical terms such as impedance, Inertanz, cargo, sound power, energy, wave, medium, signal transmission, absorption, transmission, etc.
  • Note 2: acoustical is used, if not directly a physical reference is to be created, such as: Society, method, engineering, education, glossary, a symbol, problem, measurement, point of view, use, investment, standards, etc.
Acoustic reflex

(Engl. stapedius reflex, tensor tympani reflex), see Stapedius, Tensor Tympani

Acoustic trauma

An acoustic trauma (Engl. acoustic trauma) is a violation of the ear, caused by a sudden and intense acoustic charm of a temporary hearing loss or permantenten to some extent.

  • Note 1: Explosionsknalle or other intense noise events are examples of such stimuli.
Acoustic shadow

see sound shadow

Acoustic scattering

Acoustic scattering (Engl. acoustic scattering) is the irregular reflection, refraction or diffraction a sound in many directions.

algorithm

Algorithm (Engl. Algorithm; algorithm): An algorithm is a systematic procedure for evaluating a mathematical function; quantitative model. [PAR]

Allpaß network

Allpaß Network (Engl. All-pass network; Allpaß Network): A Allpaß Network is a network, which phase shifts or time delays introduced without a significant slowdown at any frequency cause.

Amplitude

Amplitude (Engl. amplitude; amplitude): amplitude is the peak (peak) value of a function, see Peak, RMS, Average amplitude.

Amplitude spectrum

Amplitude spectrum (Engl. amplitude spectrum; amplitude spectrum): The amplitude spectrum of a time is a function describing the same in their components, each with a different frequency and (usually) different amplitude (see spectrum, phase spectrum).

Anacusis

Anacusis (syn deafness).

Analysis

Analysis (Sheet Analysis; analysis): The term analysis is in the psycho-acoustics mainly used in the following context: a) spectral analysis and time, b) Analytical listening and c) Musical analysis. [PAR]

Analytical Listen

Analytical Listening (Engl. analytical listening; Analytical listening): analytical listening is the way a sound sensation in one or more components of a complex sinusoidale Tones (sound) diskriminativ be heard, the sensation of sinusoidalen components outweigh the overall sensation of sound allowing several pitches simultaneously heard. The ratios between the different pitches are affected more by commonality pitch by pitch as close. [PAR]

Anchor attraction

Anchor attraction (Engl. anchor sound; anchor attraction): Under the anchor attraction is the invariant attraction, which - usually in a psychoacoustic experiment - with a number of stimuli compared, in one or more stimulus sizes differ. [PAR]

Antiphasig

Antiphasig (Engl. Antiphasic; Antiphasig): Antiphasig refers to the condition in which the stage or the time difference of the signal, which is offered each ear, is a fixed, different from 0 value of the phase or the time difference a noise at each Ear is different.

  • Note: An example of a antiphasige condition is such that when the phase of the signal in one ear, relative to other vice versa (opposition), while the phase noise in both ears is offered.
Anti-resonance

Anti-resonance (Engl. antiresonance; anti-resonance): For a system in forced anti-vibration resonance exists at a point when even the smallest change in the excitation frequency an increase in system response (response) at this point causes.

Mean value

Mean value (Eng: arithmetic mean, average): See mean.

Atonal

Atonal (Engl. atonal; Atonal): With atonal music that is described in the harmonious relationships should be avoided (eg Zwölftonmusik), it follows that little or no sensation of a tonal center. [PAR]

Attitude

Attitude (Engl. attitude; Attitude): Different way of a sound sensation, for example: analytical versus holistic, spontaneous, versus inzidentell willingly, intentional, etc. [PAR]

Attribute

Attribute (Engl. audio frequency; audio frequency): An audio frequency is every frequency to a normally audible sound wave.

  1. The range of audio frequencies is (roughly) between 15 Hz and 20000 Hz
  2. The word audio can also be used to a device or a system to designate which in the field of audio frequencies; example: audio amplifier.
Audio grams thresholds

Audiogram, emerging audio grams (Engl. audiogram, audiogram threshold; audio grams): An audio grams is a curve, the hearing loss as a function of frequency.

Audio grams masking

Audiogram, masking audio grams (Engl. masking audiogram; audio grams, Maskierungs): A mask audiogram is a graphical representation of masking the noise by a particular cause. The curve shows the masking in dB as a function of frequency of the masked sound.

Aurale Harmonic

Aurale Harmonic (Engl. aural harmonic; Aurale Harmonic): See harmonics, aurale.

Auditiv

Auditiv (Engl. auditory, auditory; Auditiv): The qualifying property auditory word means hearing relating to the hearing related gehörmäßig.

Auditorisches System (Engl. auditory system; Auditorisch). Psychophysiologisches system, ear, auditory nerve (Engl. auditory nerve), and auditory pathway cortex (Engl. auditory pathway, auditory area;), including where the hearing process expires.

Auditori rulers electricity

Auditori rulers current (Engl. auditory stream; Auditori current ruler): In the hearing sensation to gestalthaften elements zusammenfaßbare Warhnehmungsinhalte, the horizontal (ie in their time) deliberately structured.

  • Note: Auditory streaming improves the visibility of complex signals, with relevant and irrelevant information parameters separately processed.

B

bandwidth

The nominal bandwidth (ger. Bandbreite) of a filter is given by the difference between the upper and the lower cut-off-frequency. This difference may be expressed (1) in Hertz, (2) as percentage of the center frequency of the pass-band or (3) as the interval defined by the upper and lower cut-off-frequency in octaves (i.e. 1 octave, 1/3 octave)

  • Remark: For more definitions see also USA Standard Method for Specifying the Characteristics of Analyzers Used for the Analysis of Sounds and Vibrations, Z24.15-1955
band power level

The band power level (ger. Band-Leistungspegel) of a sound for a specific wave band is the sound power level of a sound within a limited wave band.

band pressure level

The band pressure level (ger. Band-Schallpegel) of a sound for a specific wave band is the sound pressure level of a sound within a limited wave band.

  • Remark: The wave band may be specified by its lower and upper cut-off-frequency or by its pass-band and the bandwidth. The bandwidth of the band may be specified as follows: octave-band (sound) pressure, half-octave-band pressure, third-octave-band pressure, 50-Hz-band pressure.

C

cut-off-frequency

The cutoff frequency (ger. Grenzfrequenz, Eckfrequenz) is the frequency nearest to the center frequency where the level exceeds ±3dB.

D

decacy time

decay time (ger. Abfallzeit) In general it is the time between a sound pressure level and a lower sound pressure level. Both levels have to be defined explicitly. It is also useful to describe the decay time as speed of lowering sound pressure level (db/sec).

  • Note1: The decay time constant characterizes the exponential decacy of sound after stopping the sound source (Unit: s-1).
  • Note2: If p0 is the effective sound pressure after stopping the sound source at t = 0 and p(t) is the effective sound pressure level at t, and p(t) = p0*e-k*t is imperative, then k is the decay constant.

E

F

forward masking

(ger. Nachverdeckung): see also "masking".

G

H

I

K

L

M

N

neper

Neper (Np) (ger. Neper) is a unit used to express ratios, such as gain, loss, and relative values.

  • The neper is analogous to the decibel, except that the Naperian base e (2.718281828...) is used in computing the ratio in nepers.
  • The value in nepers, Np, is given by Np = ln(x1/x2), where x1 and x2 are the values of interest, and ln is the natural logarithm, i.e., logarithm to the base e.
  • One neper (Np) = 8.686 dB, where 8.686 = 20/(ln 10).
  • One dezibel (dB) = 0.1151 Np, where 0.1151 = ln(10)/20.
  • The neper is often used to express voltage and current ratios, whereas the decibel is usually used to express power ratios.
  • Np is a dimensionless unit (like dB).
  • The ITU recognizes both units.
nominal bandwidth

See bandwidth

O

R

reverberation

Reverberation (ger. Nachhall) is all sound due to reflexions measured in a closed system (room) after the sound source has stopped activity.

reverberation time

The reverberation time (ger. Nachhallzeit) is defined as the time needed the sound level reaches -60dB of average active sound level after stopping the sound source.

S

speech transmission index

Speech transmission index (ger. Sprachverständlichkeit) is a number between 0 an 1 representing the normal human ability to understand the contents of a spoken message based on sound properties. 0 represents a bad STI, 1 represents best STI. Derivates of the STI are RASTI (rapid speech transmission index) and STIPA (STI public address - a spezialized selection of representative data for public address applications).

T

U

V

W

Z

References

  • [ANSI] American National Standard Psychoacoustical Terminology (1973): ANSI S3.20-1973; Approved December 5, 1973; American National Standard Institute, Inc.
  • [YOST] Yost, William A. & Donald W. Nielsen (1977): Fundamentals of Hearing. An Introduction. Holt, Rinehart and Winston; New York.
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