Audio analysis refers to the extraction of information and meaning from audio signals for analysis,

classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

, storage, retrieval,

synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors ** Organic synthesis, the chemical synthesis of organ ...

, etc. The observation mediums and interpretation methods vary, as audio analysis can refer to the human ear and how people interpret the audible sound source, or it could refer to using technology such as an

Audio analyzer An audio analyzer is a test and measurement instrument used to objectively quantify the audio quality measurement, audio performance of electronic and electro-acoustical devices. Audio quality metrics cover a wide variety of parameters, including a ...

to evaluate other qualities of a sound source such as

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplit ...

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal ...

frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of sy ...

, and more. Once an audio source's information has been observed, the information revealed can then be processed for the logical, emotional, descriptive, or otherwise relevant interpretation by the user.

Natural Analysis

The most prevalent form of audio analysis is derived from the sense of

hearing Hearing, or auditory perception, is the ability to perceive sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psycholog ...

. A type of sensory perception that occurs in much of the planet's fauna, audio analysis is a fundamental process of many living beings. Sounds made by the surrounding environment or other living beings provides input to the hearing mechanism, for which the listener's brain can interpret the sound and how it should respond. Examples of functions include

speech Speech is a human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if ...

startle response In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening stimuli, such as sudden noise or sharp movement, and is associated with negative Affect (psychology), affect.Rammirez-Moreno, D ...

music Music is generally defined as the art of arranging sound to create some combination of form, harmony, melody, rhythm or otherwise expressive content. Exact definitions of music vary considerably around the world, though it is an aspect ...

listening, and more. An inherent ability of humans, hearing is fundamental in communication across the globe, and the process of assigning meaning and value to speech is a complex but necessary function of the human body. The study of the auditory system has been greatly centered using mathematics and the analysis of sinusoidal vibrations and sounds. The

Fourier Transform A Fourier transform (FT) is a mathematical transform that decomposes functions into frequency components, which are represented by the output of the transform as a function of frequency. Most commonly functions of time or space are transformed, ...

has been an essential theorem in understanding how the human ear processes moving air and turns it into the audible frequency range, about 20 to 20,000 Hz. The ear is able take one complex waveform and process it into varying frequency ranges thanks to differences in the structures of the ear canal, that are tuned to specific frequency ranges. The initial sensory input is then analyzed further up in the neurological system where the perception of sound takes place. The auditory system also works in tandem with the neural system so that the listener is capable of spatially locating the direction from which a sound source originated. This is known as the Haas or Precedence effect and is possible due to the nature of having two ears, or auditory receptors. The difference in time it takes for a sound to reach both ears provides the necessary information for the brain to calculate the spatial positioning of the source.

Signal Analysis

Audio signals can be analyzed in several different ways, depending on the kind of information desired from the signal. Types of signal analysis include: * Level and gain *

Frequency domain In physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency, rather than time. Put simply, a time-domain graph shows how a signa ...

analysis *

Frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of sy ...

* Total Harmonic Distortion plus Noise (THD+N) *

Phase Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform * Phase space, a mathematic ...

Crosstalk In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, induc ...

Intermodulation distortion Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency com ...

(IMD) *Stereo and Surround THX-DeepNote-Spectogram

Hardware analyzers have been the primary means of signal analysis since the invention of the first audio analyzer, made by

Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

, the

HP200A The HP 200A was the first product made by Hewlett-Packard and was manufactured in David Packard's garage in Palo Alto, California. It was a low-distortion audio oscillator used for testing sound equipment. It used the Wien bridge oscillator cir ...

. Hardware analyzers are typically used in engineering, testing, and manufacturing of professional and consumer grade products. As computer technology progressed, integrated software found its way into these hardware systems, and later there would be audio analysis tools that did not require any hardware components save for the computer running the software. Software audio analyzers are regularly used in various stages of music production, such as live audio, mixing, and mastering. These products tend to employ Fast Fourier Transform (FFT) algorithms and processing to provide a visual representation of the signal being analyzed. Display and information types include frequency spectrum, stereo field,

surround Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener (surround channels). Its first application was in movie theaters. Prior to sur ...

field,

spectrogram A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time. When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represen ...

, and more.

References

{{DEFAULTSORT:Audio Analysis Audio engineering

Natural Analysis

Signal Analysis

See also

References