ASA - Acoustical Society of America

ASA S1.11

Thu, 01 Jan 2009 00:00:00 GMT

ASA S1.11; Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters - Includes Errata: 2005 ASA - Acoustical Society of America This standard provides performance requirements for analog, sampled-data, and digital implementations of bandpass filters that comprise a filter set or spectrum analyzer. The extent of the passband region of a filter's relative attenuation characteristic is a constant percentage of the midband frequency for all filters of a given bandwidth. An instrument complying with the requirements of this standard may contain any number of bandpass filters covering any desired frequency range. Methods for testing the performance of filters are given in an informative annex.
Performance requirements are provided for three filter classes designated class 0, class 1, and class 2. Allowed tolerance limits increase as the class number increases.
Bandpass filters conforming with the performance requirements of this standard may be part of various measurement systems or may be an integral component of a specific instrument and shall operate in real time. Performance requirements apply to any method that is selected by the manufacturer to implement the design of the filters.
Instruments conforming with the requirements of this standard are capable of provi ding frequencyband- filtered spectral information for a wide variety of signals, for example, time-varying, intermittent, and steady; broadband and discrete frequency; and long and short durations. For applications involving transient signals, different realizations of filters meeting the requirements of this standard may give different results.

ASA S1.40

Sat, 01 Jan 2011 00:00:00 GMT

ASA S1.40; Specifications and Verification Procedures for Sound Calibrators ASA - Acoustical Society of America Sound calibrators generate known sound pressure levels at one or more frequencies in a coupler into which a specified model of microphone is inserted in a specified configuration.
NOTE An example of a specified configuration may be with or without a grid.
This Standard specifies performance requirements and verification procedures for three classes of coupler-type sound calibrators:
— Class LS: Laboratory Standard calibrator with the smallest tolerance limits.
— Class 1: Sound calibrators that are generally intended for field use with class 1 sound level meters and similar instruments.
— Class 2: Sound calibrators that are generally intended for field use with class 2 sound level meters, dosimeters, and similar instruments.
For class LS calibrators, the Standard requires the use of a laboratory standard microphone as specified in ANSI S1.15-1997/Part 1. For class 1 and class 2 calibrators, the Standard requires the use of a working standard microphone as specified in IEC 61094-4:1995.
Tolerance limits in this Standard include maximum permitted expanded uncertainties of measurement as well as the tolerance limits allowed for design and manufacturing.
This Standard applies to sound calibrators that are used to check or adjust the sensitivity of sound measuring instruments and systems including conventional, integrating-averaging and integrating sound level meters, and personal noise dosimeters.
This Standard does not include requirements for the Instruction Manual to provide data for use in adjusting a sound level indicated by a sound level meter, or equivalent instrument, in response to application of a sound calibrator to the equivalent free-field or random-incidence sound level.
Sound calibrators may provide two or more sound pressure levels and operate at two or more frequencies. These multiple-level / multiple-frequency calibrators have a single class designation for all combinations of levels and frequencies for which the Instruction Manual states conformance to the requirements of this Standard.
Additional useful functions such as tonebursts may be provided. Requirements for these additional functions are not included in this Standard.

ASA S3.2

Thu, 01 Jan 2009 00:00:00 GMT

ASA S3.2; Method for Measuring the Intelligibility of Speech over Communication Systems ASA - Acoustical Society of America The scope of this standard includes the measurement of the intelligibility of speech over entire communication systems and the evaluation of the contributions of elements of speech communication systems. The scope also includes evaluation of the factors that affect the intelligibility of speech.
In this standard the intelligibility of speech over a speech communication system is measured by comparing the monosyllabic words trained listeners receive and identify with the words trained talkers or speech coders speak into a communication system that connects the talkers (or speech coders) with the listeners. The standard requires the intelligibility measurements to be made with talkers and listeners who are native speakers of English and who have no speech or hearing defects.
Limitations. This standard specifies what should be measured and reported to assess a communication system, but it does not specify the test conditions. This limitation prohibits comparisons between evaluations done under different test conditions.
This standard is not intended for use in evaluating automatic speech recognition devices; the sets of speech materials specified in this standard have not been shown to be appropriate or valid for testing systems that include such devices.
This standard is not intended for use in evaluating the intelligibility of text-to-speech systems; the sets of speech materials specified in this standard have not been shown to be appropriate or valid for testing such systems.
This standard is not intended for use in evaluating the articulatory abilities of talkers with speech disorders or for use in evaluating the speech discrimination abilities of listeners with hearing deficiencies.
This standard is not intended for use in evaluating listeners' abilities to identify talkers or their emotional state. Neither is the standard intended for use in evaluating the overall quality of a speech communication system.
Purpose
The purpose of this standard is to establish uniform methods for measuring the intelligibility of speech over communication systems. The measurement process involves talkers, in their environment, who speak test words into a transmission path to listeners, who receive and identify the speech in their environment. Figure 1 shows a simple block diagram of such a measurement system.
This standard is intended to be particularly useful to the following groups:
− Preparers of specifications for the performance of speech communication systems, equipment, and facilities;
− Architects and consulting engineers who design spaces and equipment for speech communication;
− Developers, designers, and manufacturers who wish to describe the performance of speech communication equipment; and
− Evaluators of the performance of different talkers, environments, transmission paths (including communication equipment), listeners, or usage procedures for speech communication systems.
Others who may find portions of the standard helpful include users of speech communication systems, people who select and train such users, designers, or selectors of the environments in which the systems and equipment will be used, and people who wish to adopt or to modify parts of the standard to suit purposes which are outside its scope.
Applications
The standard is intended for use in measuring the intelligibility of English speech in either indoor or outdoor spaces over a communication system. Examples of the spaces are offices, vehicles, enclosures, auditoriums, and amphitheaters. In large spaces, where intelligibility is not uniform across the space, multiple measurements or a single measurement in a "typical" location should be made. Examples of the equipment are public address systems, telephones, intercommunication systems, radiotelephones, underwater telephones, broadcast systems, and special systems for speech communication. The standard also is intended for use in evaluating the contribution of the individual components of the communication systems, such as microphones, loudspeakers, headsets, and electronic equipment—and the contribution of the methods of using the components—to the intelligibility of speech over the communication systems.

ASA S1.13

Fri, 01 Jan 2010 00:00:00 GMT

ASA S1.13; Measurement of Sound Pressure Levels in Ai ASA - Acoustical Society of America This standard specifies requirements and procedures for the measurement of sound pressure levels in air. These requirements and procedures apply primarily to measurements performed under normal, relatively quiescent meteorological conditions. Nearly all measurements made indoors will fall under such conditions, but outdoor measurements may also be made, and may remain in conformance with this standard provided the ranges of certain environmental variables are restricted, as described herein.
The requirements in this standard (identified by the use of the word shall) are to be understood as conditions on the measurements that must be met in order to state that such measurements have been made in conformance with this American National Standard. The guidelines and recommendations (identified by the use of the word should) are to be understood as conditions that will generally improve the accuracy, validity, applicability, documentation, and reporting of the measurement data but that are not mandatory for conformance.
The type of sounds considered by this standard may differ widely in temporal and spectral characteristics. The sound to be measured may be continuous or intermittent; it may be steady, fluctuating, or impulsive; and it may be essentially broad band or contain discrete tones or narrow bands of noise.
The frequency range covered by the requirements of this standard depends on the specific type of sound level meter or instrumentation being used, but, in general, the frequency content of the sound being measured should be contained within the range covered by the octave bands having center frequencies from 31.5 Hz to 16.0 kHz. The sound pressure levels of sounds whose energy is concentrated outside of this range may not be measured accurately according to the procedures of this standard.
The sound pressure level descriptors primarily used in this standard are the time-average A-weighted sound level (also called the equivalent-continuous A-weighted sound pressure level) and the A-weighted sound exposure level. The choice of descriptor and the measurement procedures to follow depend on the type of sound, and this standard gives requirements and guidelines governing this choice.
The nature of the sound that is being measured by the procedures of this standard may be considered as either desirable (e.g., music from a symphony orchestra or a signal from an alarm device) or undesirable (e.g., noise from a busy highway or household vacuum cleaner). There is no differentiation as far as the procedures in this standard are concerned.
This standard does not address the measurement of sound pressure levels in environments other than air (such as other gases, liquids, or solids), the measurement of infrasonic or ultrasonic sounds, or (generally) the measurement of sound pressure levels outdoors in nonquiescent conditions.