Research On Realizing Method Of Mobil Loudness Meter Based On Digital Signal Processor

The sound pressure level is often treated as the standard parameter currently for evaluating the noise level in traditional noise measurement. However, sound loudness is better than the sound pressure level to simulate the sensation of the human hearing, especially in the condition that we need some subjective judgments. Because the measuring of the sound loudness is based on the human hearing sensation, it is the trend of the noise evaluation in the future.According to this trend, the mobile sound loudness meter, which is based on the digital signal processing (DSP) technology, is developed in this thesis. The digital model of sound loudness calculation, basing on Steve's sound loudness calculation method, is also established. Using this model, an instrument of sound loudness is developed including the hardware and the software. This instrument can do the process from picking sound to displaying the final sound loudness result. Moreover, this instrument also proves the feasibility of the mobile sound loudness meter.The main processes of sound loudness calculation are transition of analog signals to digital signals, bandpass filtering, Fast Fourier Transformation (FFT) and sound loudness calculation. The key algorithms related to these processes are studied in this thesis. The aim of this study is to make these algorithms better, according to the character of the DSP hardware source, and reasonably choose the key parameters.Accompanying with the character of the mobile sound loudness meter, a digital signal processor, TMS320VC5402, with low energy-consuming, which is made by TI Company, is used in the research. The interface of the AD signals transition, the interface of the power management chip, the interface of the extended program storage and the extended data storage are also studied in this thesis. Using advantage of the readability of the C language in main frame of program and the high speed of the assembly language in core algorithm, the software developed in this thesis is wrote by C language and assembly language. The simulation test verifies the feasibility of the algorithm and reliability of the hardware system. This thesis also provides the feasibility verifying and applied technology for the marketing of mobile digital sound loudness meter.