【正文】 to acquire, analyze and present audio data. The most mon measurements are presented as well as the LabVIEW code to perform multiple tasks in the audio measurement process.IntroductionModern software and hardware technologies empower engineers to analyze many aspects of a sound signal. Programming software such as LabVIEW gives us the ease of use, performance, and powerful functionality needed to develop plex measurements in a short time. This paper describes the steps to develop an audio measurement system based on LabVIEW industrystandard measurement software that delivers better productivity while providing scalability.Modern audio measurements are among the most demanding operations for a digital measurement system. To perform successful audio measurements the software must be able to perform several tasks (such as data scaling, filtering, analysis, and visualization). From acquiring the data to presenting the results, LabVIEW has the flexibility and modularity to assure precise measurements. National Instruments offers the possibility to expand the power of LabVIEW with a toolkit designed to make sound and vibration measurements easier. National Instruments hardware and software integrate seamlessly to replace many box instruments and offer much more customization and power.The following section presents a general explanation of some mon tasks in audio measurements. The examples in this paper use LabVIEW professional development system or full development system, some of them using the NI Sound and Vibration Toolkit. The examples can be easily integrated to create a custom audio measurement system.Data Acquisition, Scaling, and WeightingMost measurement systems begin with some form of sensor or transducer that generates electrical signals according to physical phenomena. The process of measuring those electrical signals and inputting them to a puter for processing is known as data acquisition. Dynamic signals such as audio require highresolution and highdynamicrange digitizing devices. National Instruments NI 4461 devices offer both 24bit analogtodigital converters (ADCs) and 24bit digitaltoanalog converters (DACs) to simultaneously acquire and generate analog signals over a bandwidth from DC to 92 kHz to ensure highresolution measurements. The acquired data is then plotted in a graph.Signal ScalingThe NI Sound and Vibration Toolkit offers highlevel VIs that present data with the appropriate units – that is timedomain data in the correct engineering units, frequency data in decibels, etc. However, values acquired via a data acquisition device usually have a linear relationship with the voltage ing from the sensor。 raw data es in regular voltage units. Signal scaling is the required process of converting the voltage values to the correct engineering units. The SVS Scale Voltage to provides an easy way to scale a voltage signal to units such as Pascals (Pa), g, m/s178。, etc. The scaling VI is the bridge between raw data ing from the digitizer and a useful value related to the microphone or sensor being used. In order to get an accurate scaling of a signal, calibrating the system might be necessary. Calibration can be achieved when there is a known relationship between a measured value and the value provided by a standard. In audio measurement systems calibration requires an external sound source with a known value, usually ing from a pistonphone or an acoustic calibrator. The Sound and Vibration Toolkit provides calibration VIs that help to ensure the accuracy of the plete measurement system.Weighting FiltersMeasurement hardware is usually designed to have a flat response across the audio frequency band. On the other hand, the human ear has a nonlinear response. Because in most cases the final sensor is the human ear, we need to pensate our measurements to fit a model of our ears. Using weighting filters is the standard way to best describe our subjective perception of sound. Traditionally, weighting filters are built using analog ponents。 however, the Sound and Vibration Toolkit offers digital weighting filters for time and frequency data.Audio Measurements with LabVIEWHaving acquired, scaled and weighted an audio signal, we are now ready to take advantage of the processing power of our puter to perform plex signal analysis. This section describes mon audio measurements used throughout the industry. A brief explanation is provided together with example code that demonstrates how to perform these measurements with the Sound and Vibration Toolkit.SingleTone InformationSeveral standard methods for audio measurements require the excitation and analysis of a single tone. The NI Sound and Vibration Toolkit offers an Express VI to extract important information about a tone found in a signal. The Tone Measurement Express VI finds the tone with the highest amplitude on the signal and calculates the amplitude and frequency. This VI also has the option to export a spectrum and additional tone analysis. For better performance, this VI can also narrow the search to a specified frequency band. This example was limited to a singlechannel analysis, but this VI is capable of analyzing several channels simultaneously.RMSFor certain applications the amplitude of a signal is not enough information. In many measurements, such as gain calculations and power, the rootmeansquare (rms) value of a signal is required. The NI Sound and Vibration Toolkit provides a VI that easily putes the rms value by squaring the instantaneous signal data, integrating over the desired time, and taking the square root. The Amplitude and Level Express VI is also capable of averaging the rms values calculated from the signal. This VI also includes the option of time windowing for better measurements. GainOne of the basic measurements performed on an audio system is gain. The system gets a stimulus signal and generates a response signal. The factor by whic