This is the generic class for apparatus and corresponding methods for constructing, analyzing, and modifying units of human language by data processing, in which there is a significant change in the data.
This class also provides for systems or methods that process speech signals for storage, transmission, recognition, or synthesis of speech.
This class also provides for systems or methods for bandwidth compression or expansion of an audio signal, or for time compression or expansion of an audio signal.
Class 704 is structured into three main divisions:
A. Linguistics.
B. Speech Signal Processing.
C. Audio Compression.
See Subclass References to the Current Class, below, for the subclasses located within each of these three main divisions.

LINES WITH OTHER CLASSES AND WITHIN THIS CLASS
A. LINGUISTICS
1. This class does not include subject matter wherein significant details of the modification or construction of documents are claimed. (See Class ?0? in the Search Class notes below in References to Other Classes, regarding Document Processing).
2. This class does not include subject matter directed to significant details of teaching languages. (See Class 434 in the Search Class notes in References to Other Classes, below).
3. This class does not include subject matter directed to significant details of the construction, analysis or modification of computer languages. (See Class 395 in the Search Class notes in References to Other Classes, below).
B. IMAGE ANALYSIS
1. This class does not include subject matter wherein significant image analysis is performed and speech signal processing is nominally claimed (see Class 382 in the Search Class notes in References to Other Classes, below).
2. This class includes subject matter directed to speech signal processing disclosed or claimed in plural diverse arts such as image analysis (classified, per se, in Class 382).
C. AUDIO SIGNAL PROCESSING
1. This class does not include subject matter wherein nominal bandwidth or time modifications are performed for other audio processing defined in Classes 381 or 84 (see Search Class notes below in References to Other Classes). Examples of subject matter not included are: Stereo, sound effects, hearing aids, input and output transducers, and musical instruments.
2. This class includes audio signal processing wherein significant processing is performed to modify the signal's bandwidth or time characteristics for compression or expansion of the signal.
D. COMMUNICATIONS
1. This class does not include subject matter wherein significant details of a distinct communications system or telephone link is performed and speech signal processing is nominally claimed (see Classes 340, 370, 375, 379, 455 in the Search Class notes below in References to Other Classes.).
2. This class includes subject matter directed to speech signal processing disclosed or claimed in plural diverse arts such as various types of communication systems.
E. APPLICATIONS
1. This class does not include subject matter wherein significant details of application systems are performed and speech signal processing is nominally claimed.
2. This class includes subject matter directed to speech signal processing disclosed or claimed in plural diverse arts
to include electrical and mechanical systems. Examples would include systems controlled by speech recognition, systems which create specific displays of speech data, systems for editing speech data and otherwise unrelated systems which incorporate speech signal processing details such as placing a speech synthesizer into novelty items.

SEE OR SEARCH THIS CLASS, SUBCLASS:
1 for linguistics.
100 for speech signal processing.
500 for audio compression.

REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:
84, Music, 1 for instruments used in producing music to include (a) electrical music instruments, (b) automatic instruments, and (c) hand-played instruments. Automatic and hand-played instruments are divided into four groups: stringed, wind, rigid vibrators, and membranes. This class also includes some accessory devices generally recognized as belonging to the art or industry.
181, Acoustics, various subclasses, for mechanically transmitting, amplifying and ascertaining the direction of sound and for mechanically muffling or filtering sound.
340, Communications: Electrical, 825 for controlling one or more devices to obtain a plurality of results by transmission of a designated one of plural distinctive control signals over a smaller number of communication lines or channels.
341, Coded Data Generation or Conversion, various subclasses for electrical pulse and digit code converters (e.g., systems for originating or emitting a coded set of discrete signals or translating one code into another code wherein the meaning of the data remains the same but the formats may differ).
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, various subclasses for the selective control of two or more light generating or light controlling display elements in accordance with a received image signal, and 1 for visual display systems with selective electrical control including display memory organization and structure for storing image data and manipulating image data between a display memory and display device.
360, Dynamic Magnetic Information Storage or Retrieval, which is an integral part of Class 369 following subclass 18, for record carriers and systems wherein information is stored and retrieved by interaction with a medium and there is relative motion between a medium and a transducer, for example,
magnetic disk drive devices, and control thereof, per se.
365, Static Information Storage and Retrieval, various subclasses for addressable static singular storage elements or plural singular storage elements of the same type (i.e., the internal elements of memory, per se).
369, Dynamic Information Storage or Retrieval, various subclasses for record carriers and systems wherein information is stored and retrieved by interaction with a medium and there is relative motion between a medium and a transducer.
370, Multiplex Communications, for the simultaneous transmission of two or more signals over a common medium, particularly 58.1 for time division multiplex (TDM) switching, subclasses 85.1+ for time division bus transmission, and subclasses 91+ for asynchronous TDM communications including addressing.
375, Pulse or Digital Communications, various subclasses for generic pulse or digital communication systems and synchronization of clocking signals from input data.
377, Electrical Pulse Counters, Pulse Dividers, and Shift Registers: Circuits and Systems, various subclasses for generic circuits for pulse counting.
379, Telephonic Communications, various subclasses for two-way electrical communication of intelligible audio information of arbitrary content over a link including an electrical conductor.
380, Cryptography, 3 for stored information access or copy prevention (e.g., software program protection or computer virus detection) in combination with data encryption, and subclasses 22 through 25 and 50 for electric signal modification and other appropriate subclasses.
381, Electrical Audio Signal Processing Systems and Devices, various subclasses for wired one-way audio systems, per se.
382, Image Analysis, various subclasses for operations performed on image data with the aim of measuring a characteristic of an image, detecting variations, detecting structures, or transforming the image data, and for procedures for analyzing and categorizing patterns present in image data.
434, Education and Demonstration, 112 for communication aids for the handicapped, subclasses 156+ for education and demonstration of language, subclasses 322+ for question or problem eliciting response.
455, Telecommunications, appropriate subclasses for modulated carrier wave communication, per se, and subclass 26.1 for subject matter which blocks access to a signal source or
otherwise limits usage of modulated carrier equipment.
700, Data Processing: Generic Control Systems or Specific Applications, subclasses 1-89 for data processing generic control systems, subclasses 90-306 for applications of computers in various environments.
702, Data Processing: Measuring, Calibrating, or Testing, appropriate subclasses for the application of computer data processing in measuring, calibrating, or testing.
707, Data Processing: Database and File Management, Data Structures, and Document Processing, 500 for document processing including layout, editing, and spell-checking.
708, Electrical Computers: Arithmetic Processing and Calculating, 1 for hybrid computers, subclasses 100+ for calculators, digital signal processing and arithmetical processing, per se, subclasses 300+ for digital filters, and subclasses 800+ for electric analog computers.
714, Error Detection/Correction and Fault Detection/Recovery, various subclasses for generic electrical pulse or pulse coded data error detection and correction.

GLOSSARY:
The terms below have been defined for purposes of classification in this class and are shown in underlined type when used in the class and subclass definitions. When these terms are not underlined in the definitions, the meaning is not restricted to the glossary definitions below.
CORRELATION
A statistical measurement of the interdependence or association between two variables that are quantitative or qualitative in nature. A typical calculation would be performed by multiplying a signal by either another signal (cross-correlation) or by a delayed version of itself (autocorrelation).
DISTANCE
A statistical measurement for comparing elements defined by variables or vectors using scalar or vector subtraction of those elements. Examples: distance=a-b, |a-b|, (a-b).5 or two vectors may be treated as objects such that the straight line distance is measured between them.
EXCITATION
Stimulation of the vocal tract by vibratory action of the vocal cords or by a turbulent air flow. In a digital system, the vocal tract is typically modelled with a filter and excitation of the filter is performed using time representations of pitch (voiced excitation) and noise
(unvoiced excitation).
LANGUAGE
A systematic means of communicating ideas or feelings by the use of conventionalized sounds, gestures, or marks having understood meanings.
LINGUISTICS
The study of human speech including the units, nature, structure, and modification of language.
NOISE
Any sound which is undesirable and interferes with one's hearing or with a system's analysis of desired sound.
PITCH
The measurable frequency or period at which the glottis vibrates.
SIMILARITY
A statistical measurement which is inversely proportional to distance. For example, if two patterns are compared yielding a small distance, then the patterns would exhibit a large (or high degree of) similarity.
SPEECH
The communication or expression of thoughts in spoken words.
UNVOICED
Speech sounds produced by a turbulent flow of air created at some point of stricture in the vocal tract and usually lacking pitch.
VOICED
Speech sounds produced by vibratory action of the vocal cords and usually having pitch.

LINGUISTICS
This subclass is indented under the class definition. Subject matter including means or steps for constructing a word, a phrase, or a sentence in a language.

SEE OR SEARCH CLASS:
434, Education and Demonstration, 156 for demonstration and education in linguistics.

Translation machine:
This subclass is indented under subclass 1. Subject matter wherein a language (i.e., source language) stored in a memory means is translated into another language (i.e., target language).

SEE OR SEARCH THIS CLASS, SUBCLASS:
9 for translation machines with significant natural language processing.

SEE OR SEARCH CLASS:
358, Facsimile and Static Presentation Processing, subclass 403 for document filing and retrieval system.
716, Data Processing: Design and Analysis of Circuit or Semiconductor Mask, subclass 3 for translation of computer program in designing and analyzing circuits and semiconductor mask.
717, Data Processing: Software Development, Installation, and Management, subclasses 5-9 for software program code translator or compiler in software development.

Having particular Input/Output device::
This subclass is indented under subclass 2. Subject matter wherein the translation machine includes a means for reading into the memory means a language, for pronouncing the translated language or a particular user interface.
(1) Note. Examples of such devices include an optical scanner or voice synthesizer.

Based on phrase, clause, or idiom:
This subclass is indented under subclass 2. Subject matter wherein the translation machine translates a series of words
that form a syntactical unit.

For partial translation:
This subclass is indented under subclass 2. Subject matter wherein the translation machine includes a means for providing translation for a specified portion of a sentence or a clause.

Punctuation:
This subclass is indented under subclass 2. Subject matter wherein the translation machine translates a compound word formed by hyphenation or sentences with quotation marks, colons, semicolons, or parentheses.

Storage or retrieval of data:
This subclass is indented under subclass 2. Subject matter including a means for assigning storage locations or accessing addresses to the memory means.

SEE OR SEARCH CLASS:
707, Data Processing: Database and File Management, Data Structures, and Document Processing, 1, for database or file access methods.

Multilingual or national language support:
This subclass is indented under subclass 1. Subject matter including means or steps to adapt to, process, or support plural languages in systems or in software (i.e., providing language identifiers on files or providing screen prompts in a selected language), or to support the conventions or peculiarities of various national languages (i.e., alphabetical ordering, date or currency indications).

SEE OR SEARCH THIS CLASS, SUBCLASS:
200 for details of translation between multiple languages.

SEE OR SEARCH CLASS:
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Processing, 333 for customization or edition of operator interfaces.
707, Data Processing: Database and File Management, Data Structures, or Document Processing, subclass 536 for composing or editing multiple languages in a document.

Natural language:
This subclass is indented under subclass 1. Subject matter includes a means for applying grammatical rules or other analyses (e.g., morphemic, syntax, semantic, etc.) to define the true meaning of a sentence or phrase.
(1) Note. When words are undefined in the dictionary of a natural language, the grammatical rules or other analyses are applied in order to determine the true meaning of a sentence or a phrase.

SEE OR SEARCH CLASS:
707, Data Processing: Database and File Management, Data Structures, and Document Processing, 1, for nominal natural language processing used in database search and retrieval.

Dictionary building, modification, or prioritization:
This subclass is indented under subclass 1. Subject matter including a construction, a change, or an orderly arrangement of dictionary, thesauri, or the like.

SEE OR SEARCH THIS CLASS, SUBCLASS:
9 for mere use in natural language processing.
200 for mere use in translation.

SEE OR SEARCH CLASS:
707, Data Processing: Database and File Management, Data Structures, or Document Processing, subclass 102 for database details of dictionaries, and subclass 532 for mere use of a dictionary in editing or composition of a document.

SPEECH SIGNAL PROCESSING:
This subclass is indented under the class definition. Subject matter wherein the system performs operations or functions on signals which represent speech.

SEE OR SEARCH THIS CLASS, SUBCLASS:
500 for audio (other than speech) signal bandwidth compression or expansion.

SEE OR SEARCH CLASS:
379, Telephonic Communications, appropriate subclasses for speech signal processing in a telephone system or device.

For storage or transmission:
This subclass is indented under subclass 200. Subject matter wherein the speech, which may be in coded or reduced formats, is stored or transmitted.

Neural networks:
This subclass is indented under subclass 201. Subject matter wherein coding is performed using parallel distributed processing elements constructed in hardware or simulated in software.

SEE OR SEARCH CLASS:
395, Information Processing System Organization, subclass 259, for neural networks which decode a coded speech signal.

Transformations:
This subclass is indented under subclass 201. Subject matter wherein the speech is encoded using a specific mathematical function (e.g., Fourier, Walsh, cosine/sine transform, etc.).

Orthogonal functions:
This subclass is indented under subclass 203. Subject matter wherein the function is orthogonal (transformations as applied to vector, matrix, linear and polynomial functions, for example).

Frequency:
This subclass is indented under subclass 201. Subject matter wherein the speech is represented by frequency.

Specialized information:
This subclass is indented under subclass 205. Subject matter wherein the frequency data is analyzed to identify specific speech information.

Pitch:
This subclass is indented under subclass 206. Subject matter wherein the specific speech information represents the predominant frequency of the speech.

Voiced or unvoiced:
This subclass is indented under subclass 207. Subject matter wherein the specific speech information represents the presence (voiced) or absence (unvoiced) of predominant frequency components.

Formant:
This subclass is indented under subclass 206. Subject matter
wherein the specific speech information represents the frequency values of any of several resonance bands which determine the phonetic quality of a vowel sound.

Silence decision:
This subclass is indented under subclass 206. Subject matter wherein the specific speech information represent the presence or absence of speech.

Time:
This subclass is indented under subclass 201. Subject matter wherein the speech signal is represented using time (e.g., time measurements and energy measured over time).

Pulse code modulation (PCM):
This subclass is indented under subclass 211. Subject matter wherein the signal is sampled over time, and the magnitude of each sample is quantized and converted into a digital signal.

Zero crossing:
This subclass is indented under subclass 211. Subject matter wherein the zero crossings of the signal are used to measure time or frequency.

Voiced or unvoiced:
This subclass is indented under subclass 211. Subject matter wherein time measurements are used to determine the presence (voiced) or absence (unvoiced) of predominant frequency components.

Silence decision:
This subclass is indented under subclass 211. Subject matter wherein time measurements are used to determine the presence or absence of speech (e.g., pauses between words, etc.).

Correlation function:
This subclass is indented under subclass 211. Subject matter wherein analysis of speech is performed using relationships between time series samples.

Autocorrelation:
This subclass is indented under subclass 216. Subject matter wherein the relationships are between different speech samples taken from the same time series.

Cross-correlation:
This subclass is indented under subclass 216. Subject matter wherein the relationships are between speech samples taken from different time series.

Linear prediction:
This subclass is indented under subclass 201. Subject matter wherein input samples of speech are estimated from past samples of an input sequence.

Analysis by synthesis:
This subclass is indented under subclass 201. Subject matter wherein the speech signal is coded and corrected by the
difference of the decoded coded signal from the original speech signal.

Pattern matching vocoders:
This subclass is indented under subclass 201. Subject matter wherein speech signals are compared and matching patterns are encoded.

Vector quantization:
This subclass is indented under subclass 221. Subject matter wherein the encoding maps a sequence of continuous or discrete vectors into a digital sequence.

Excitation patterns:
This subclass is indented under subclass 221. Subject matter wherein the encoding models speech using representations including the primary frequency period or periods (e.g., pitch excitation, multipulse excitation, etc.).

Normalizing:
This subclass is indented under subclass 201. Subject matter wherein modifications of the speech signal emphasize or deemphasize certain features (e.g., spectral slope, average power, etc.).

Gain control:
This subclass is indented under subclass 201. Subject matter wherein the speech is adjusted to maintain an average amplitude.

Noise:
This subclass is indented under subclass 201. Subject matter wherein the coding reduces the effects of undesired signal components.

Pre-transmission:
This subclass is indented under subclass 226. Subject matter wherein the coding precedes transmission.

Post-transmission:
This subclass is indented under subclass 226. Subject matter wherein decoding after transmission minimizes the effects of noise in the transmission path.

Adaptive bit allocation:
This subclass is indented under subclass 201. Subject matter wherein limited storage or transmission resources are allocated by giving more resources to areas containing more data and giving fewer resources to areas containing less data.

Quantization:
Subject matter under 201 wherein coded information is mapped into digital words described by binary symbols.

Recognition:
This subclass is indented under subclass 200. Subject matter wherein speech is separated into discrete components which are distinguished from one another.

Neural networks:
This subclass is indented under subclass 231. Subject matter using parallel distributed processing elements constructed in hardware or simulated in software.

Detect speech in noise:
This subclass is indented under subclass 231. Subject matter wherein the discrete components are distinguished from noise.

Normalizing:
This subclass is indented under subclass 231. Subject matter wherein the discrete components are modified to emphasize or deemphasize certain features (e.g., spectral slope, average power, etc.).

Speech to image:
This subclass is indented under subclass 231. Subject matter wherein the distinguished discrete components are converted into image output (e.g., text).

Specialized equations or comparisons:
This subclass is indented under subclass 231. Subject matter wherein the discrete components are distinguished using specific mathematical functions.

Correlation:
This subclass is indented under subclass 236. Subject matter wherein the specific function measures a correlation between discrete components (e.g., absolute magnitude difference functions (AMDF), autocorrelation, cross-correlation, etc.).

Distance:
This subclass is indented under subclass 236. Subject matter wherein the specific function measures the difference between discrete components.

Similarity:
This subclass is indented under subclass 236. Subject matter wherein the specific function measures the similarity between discrete components.

Probability:
This subclass is indented under subclass 236. Subject matter wherein the specific function uses probability to determine the occurrence of a discrete component.

Dynamic time warping:
This subclass is indented under subclass 236. Subject matter wherein time components of the discrete components are aligned with reference components (e.g., using dynamic programming).

Viterbi Trellis:
This subclass is indented under subclass 236. Subject matter wherein discrete components are distinguished by traversing possible paths through a time series.

Creating patterns for matching:
This subclass is indented under subclass 231. Subject matter including specific methods for registering the discrete components to be used as references.

Update patterns:
This subclass is indented under subclass 243. Subject matter wherein the references are modified to improve recognition (e.g., learning).

Clustering:
This subclass is indented under subclass 243. Subject matter wherein similar references are placed or divided into groups (e.g., K-means algorithm, nearest neighbor, etc.).

Voice recognition:
This subclass is indented under subclass 231. Subject matter wherein different voices are distinguished (e.g., speaker identification or verification).

Preliminary matching:
This subclass is indented under subclass 246. Subject matter using an initial comparison followed by a more detailed recognition.

Endpoint detection:
This subclass is indented under subclass 246. Subject matter
including the identification of the beginning and ending points of speech sound segments.

Subportions:
This subclass is indented under subclass 246. Subject matter including separating speech into sound segments (e.g., utterances, words, phonemes, allophones, etc.).

Specialized models:
This subclass is indented under subclass 246. Subject matter including models which describe the interconnections between speech sound segments.

Word recognition:
This subclass is indented under subclass 231. Subject matter wherein different words are distinguished (i.e., the meaning of what is spoken).

Preliminary matching:
This subclass is indented under subclass 251. Subject matter using an initial comparison followed by a more detailed recognition.

Endpoint detection:
This subclass is indented under subclass 251. Subject matter identifying the beginning and ending points of words.

Subportions:
This subclass is indented under subclass 251. Subject matter identifying speech sound segments (e.g., phonemes, allophones, etc.).

Specialized models:
This subclass is indented under subclass 251. Subject matter including models which describe the interconnections between words or subportions of words.

Markov:
This subclass is indented under subclass 255. Subject matter wherein the models include states which represent speech sound portions and transitions which represent connections between speech sound portions (e.g., hidden Markov models, heuristic Markov models, etc.).

Natural language:
This subclass is indented under subclass 255. Subject matter wherein the models include grammatical constraints (e.g., syntax, etc.).

Synthesis:
This subclass is indented under subclass 200. Subject matter wherein component parts of a speech signal are combined to produce a synthetic speech output.

Neural networks:
This subclass is indented under subclass 258. Subject matter wherein synthetic speech output is formed using parallel distributed processing elements constructed in hardware or simulated in software.

Image to speech:
This subclass is indented under subclass 258. Subject matter wherein the component parts are related to image data (e.g., text to speech, etc.).

Vocal tract model:
This subclass is indented under subclass 258. Subject matter wherein the component parts model a human vocal tract.

Linear prediction:
This subclass is indented under subclass 258. Subject matter wherein the component parts are represented by coefficients derived from a sequence of past speech samples.

Correlation:
This subclass is indented under subclass 258. Subject matter wherein the component parts are represented by coefficients derived from relationships between time series speech samples.

Excitation:
This subclass is indented under subclass 258. Subject matter wherein the component parts are represented by the period of the primary frequency of the speech signal (e.g., pitch excitation, multi-pulse excitation, etc.).

Interpolation:
This subclass is indented under subclass 258. Subject matter wherein the component parts are combined using estimates of intermediate values (e.g., waveform smoothing).

Specialized model:
This subclass is indented under subclass 258. Subject matter wherein the component parts are combined or linked together in a defined manner (e.g., Markov models, trees, tries (tables representing trees), graphs, etc.).

Time element:
This subclass is indented under subclass 258. Subject matter wherein the component parts comprise time based elements (e.g., words, phonemes, allophones, etc.).

Frequency element:
This subclass is indented under subclass 258. Subject matter wherein the component parts comprise frequency based elements (e.g., pitch variations, inflection, formants, etc.).

Transformation:
This subclass is indented under subclass 258. Subject matter wherein the component parts are restored to speech using specific mathematical functions (e.g., Fourier, Walsh, Hilbert, Z-transform, cosine/sine transforms, etc.).

Application:
This subclass is indented under subclass 200. Subject matter intended or designed for a specified use to which the speech signal processing is being applied.

Handicap aid:
This subclass is indented under subclass 270. Subject matter for assisting handicapped people (e.g., blind or speech impaired communication and control).

Novelty item:
This subclass is indented under subclass 270. Subject matter for novelty items (e.g., greeting cards, toys, etc.).

Security system:
This subclass is indented under subclass 270. Subject matter for providing security (e.g., limited access).

Warning/alarm system:
This subclass is indented under subclass 270. Subject matter for providing an audible warning or alarm (e.g., multiple sensors, car gauges, etc.).

Speech controlled system:
This subclass is indented under subclass 270. Subject matter for controlling specific devices through speech or voice commands.

Pattern display:
This subclass is indented under subclass 270. Subject matter for providing visual output representing speech (e.g., computer displays of speech data).

Translation:
This subclass is indented under subclass 270. Subject matter for translating one language into another language.

Sound editing:
This subclass is indented under subclass 270. Subject matter wherein speech is edited using waveform portions or other representations of the sounds to be modified.

AUDIO SIGNAL BANDWIDTH COMPRESSION OR EXPANSION:
This subclass is indented under the class definition. Subject matter where there is either an expansion or reduction of the bandwidth required for transmission of a sound signal.
(1) Note. This subclass and its indents provide for bandwidth compression or expansion of audio signals other than speech signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
200 for expansion or reduction of a speech signal's bandwidth.
503 for time compression or expansion of audio signals.

SEE OR SEARCH CLASS:
333, Wave Transmission Lines and Networks, subclass 14 for amplitude compression and expansion in a long transmission line.
348, Television, subclasses 384.1-440.1 for bandwidth reduction of an analog television signal.
358, Facsimile and Static Presentation Processing, 426 for bandwidth reduction of a facsimile signal.
360, Dynamic Magnetic Information Storage or Retrieval, 8 for the use of a magnetic recorder to alter the bandwidth of a signal.
369, Dynamic Information Storage or Retrieval, subclass 60.01 for the use of a dynamic storage device to change the bandwidth of a signal.
370, Multiplex Communications, subclass 118 for bandwidth compression in a multiplex system.
375, Pulse or Digital Communications, subclasses 240-241 for bandwidth compression or expansion of a pulse or digital signal, particularly subclasses 240.01-240.29 for digital television.
381, Electrical Audio Signal Processing Systems and Devices, subclass 106 for amplitude compression or expansion.
455, Telecommunications, subclass 72 for message signal compression or expansion in an analog signal modulated carrier wave communication system.

With content reduction encoding:
This subclass is indented under subclass 500. Subject matter combined with means to discard and replace redundant information by a code indicating what has been discarded.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclass 55 for content reduction encoding, per se.

Delay line:
This subclass is indented under subclass 500. Subject matter having means to cause a time delay of a sound signal.

SEE OR SEARCH CLASS:
333, Wave Transmission Lines and Networks, subclasses 138-165 for delay lines, per se.

AUDIO SIGNAL TIME COMPRESSION OR EXPANSION (E.G., RUN LENGTH CODING):
This subclass is indented under the class definition.
Subject matter where there is either an expansion or reduction of the time required for transmission of a nonspeech sound signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
211 for expansion or reduction of the time required for transmission of a speech signal.
500 for frequency compression or expansion of a nonspeech audio signal.

SEE OR SEARCH CLASS:
358, Facsimile and Static Presentation Processing, 426 for time compression of a facsimile signal.
360, Dynamic Magnetic Information Storage or Retrieval, 8 for the use of a magnetic recorder to alter the time duration of a recorded signal.
369, Dynamic Information Storage or Retrieval, subclass 60.01 for the use of a dynamic storage device to alter the time duration of a recorded signal.
370, Multiplex Communications, subclass 109 for time compression or expansion in a time division multiplex system.
381, Electrical Audio Signal Processing Systems and Devices, subclass 106 for amplitude compression or expansion.
455, Telecommunications, subclass 72 for message signal compression or expansion in an analog signal modulated carrier wave communication system.

With content reduction encoding
This subclass is indented under subclass 503. Subject matter combined with means to discard and replace redundant information by a code indicating what has been discarded.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclass 55 for content reduction encoding, per se.