FYP2 WORK PROGRESS 3

This work progress focuses on audio signal analysis. Firstly, the audio signal were edited and converted into PSD using Matlab software. After that, the PSD was analyzed at certain frequencies. Lastly, all the PSD results were analyzed between different MP in each Room Sample.

Before starting the analysis, the audio signal must edited into the same range of time and same time the audio source is recorded. It is to make sure the results is more accurate. I use the website https://mp3cut.net/ to cut and edit all the audio signals.

The audio signal range were set at 7 seconds and the sound source captured at 1st second. Total of 48 audio files were edited which comprises of audio signal using Smartphone and RWA at 12 MP in 2 Room Samples.

                                    Figure 1: Cut and Edit Audio File

After editing the audio signals, the audio are converted into PSD graph using Matlab coding. Then, the PSD is determined at 125, 250, 500, 1000, 2000, 4000 and 8000Hz. After that, the Maximum, Minimum, Median and Mean of the PSD results are calculated at each frequency. Figure 2 shows the PSD graph while Figure 3 and 4 shows the PSD results at respective frequency in Room Sample 1 and 2 respectively. 

                   Figure 2: PSD Graph at MP1 in Room Sample 1

                   Figure 3: PSD Results in Room Sample 1

                Figure 4: PSD Results in Room Sample 2

Two type of result analysis were done for this work progress. The first one is to analyze the reflection pattern in both Room Samples and the second one is to determine the difference of PSD results using Real-Wave Analyzer and Smartphone. 

Analyze Sound Reflection Pattern in Room Samples

For easier analysis, the graph of PSD Results for 12 MP was constructed as shown in Figure 5 and 6.

                           Figure 5: PSD Results Graph in Room Sample 1

                       Figure 6: PSD Results Graph in Room Sample 2

For both Room Samples, Measurement Point 1 (MP1)  compared to Measurement Point 2 (MP2) at frequency 1000Hz, the PSD is lower at MP2. It is because the distance to front wall and nearest side wall is further and the distance to ceiling is constant. However, MP3 compared to MP2 at 1000Hz, when the distance to side and front wall is further but the distance to ceiling is lower, the PSD higher at MP3.

Determine the Difference of PSD Results Using Real-Wave Analyzer and Smartphone

For easier analysis, the graph of PSD results using both RWA and Smartphone were constructed in Room Sample 1 and 2 respectively as shown in Figure 7 and 8.

Figure 7: PSD Results Graph using RWA and Smartphone in Room Sample 1

Figure 8: PSD Results Graph using RWA and Smartphone in Room Sample 2

For both Room Samples, when comparing the PSD results using RWA and Smartphone at MP1 in 500Hz, the PSD using Smartphone is higher than using RWA. It is because both devices using different type of microphone, so the sensitivity is different.