Editing Sound for ALPHA IC AM4G
1. Features
1. Sound type: Insect
2. Speaker Specification: Large magnetic speaker with 29mm diameter, 8Ω resistance, 0.25 W power, and plastic film.
3. Output type: PWM
4. Objective: Raise the insect sound and filter noise.
2. Basic Operation Steps
1. Resample.
2. Use FFT filter to adjust.
3. Editing Sound
Run Cool Edit v2.1 and open a voice file (A2.wav). See the following figure 1.
Figure 1
Then select Analyze->Show Frequency Analysis to analyze frequency of A2.wav file as shown in figure 2.
Figure 2
In figure 3, you can see that the voice frequency is mainly distributed in the band from 3.5KHz to 5KHz. Hence you can do sampling in this band for insect sound. Generally the frequency of insect sound is higher than that of human voice singing. Thus, the sampling rate is relatively higher.
Figure 3
Speaker Feature
The used speaker is a large magnetic speaker with 29mm diameter, 8Ω resistance, 0.25 W power, and plastic film. The Frequency Response of this speaker is generally above 200Hz. Note that the speaker frequency responses for different factories are various. But the FR has rare effect on the insect voice.
Using FFT Filter to Edit Sound
According to the sound analyzed result and the Frequency Response of speaker, you can start to use FFT Filter to edit sound. The figure 4 shows how to open FFT Filter.
Figure 4
Secondly, you can raise the frequency band from 3.5KHz to 5KHz appropriately, and filter the band with un-obvious change (see the figure 5). Through this processing, the insect voice is stood out and the noise is eliminated. Finally the sound is edited.
