Analysis And Evaluation Methods Of Audio Signal And Its Implementation

Audio is an important kind of media in multimedia applications. Audio analysis is also extensively applied to test the characteristics of the time domain, frequency domain and distortion of various audio systems. At present, audio is still analyzed by traditional test instruments in our country, such as distortion analyzer, spectrum analyzer, etc. However, these analyzers have many defects which are very difficult to overcome, such as the single function, inefficiency, costliness, poor expandability, etc. So in order to change the traditional test mode and improve the level in audio test field, based on the theories of digital signal process, this paper has analyzed and evaluated audio signals adequately. Additionally, using the theory results, this paper adopts burgeoning virtual instruments as technology platform, designs a DVD recorder's automatic audio test system.This paper analyzes audio signals mainly from time domain, frequency domain, filter and window, etc. And based on the analysis, the audio evaluation parameters have been presented respectively. Some new algorithms of the parameters such as frequency, frequency response, THD and SNR have also been proposed. Moreover, the errors of audio generation and acquisition have been analyzed thoroughly.The test system developed by this paper is made up of hardware and software. The core of the hardware is the workstation which controls the state of DVD recorders through serial ports and controls the audio generation and acquisition module, switch module through PXI bus. Based on LabVIEW and TestStand, the system software controls the recorders, audio generation and acquisition module, switch module, operation module and the data storage. Meanwhile, the software also provides test management functions such as test flow and parameters configuration to ensure the normal running and update of the system. The system includes many kinds of technologies such as digital signal process, virtual instruments, test and control, computer, etc. Using these technologies, the system has realized automatic and accurate recorder's audio test. The total test time has been reduced to half an hour from the original 4 hours, and the production efficiency has been improved significantly.