## Friday, September 01, 2006

## Tuesday, August 22, 2006

## Friday, July 14, 2006

## Wednesday, November 02, 2005

### TunningFork C, 128 [Hz]

Hearing test uses this kind of forks, and they are the closer to a booming sand frequency. Performing the FFT of the sound (using MatLab at 8000 [samples/sec]). This might be useful to test the resonance responses in the loose sand layers with a wet sand layer (like a damp) underneath

## Wednesday, September 14, 2005

### Microphone calibration

- 8000 [samples/s] ------ 440.1855 [Hz]
- 11000 [samples/s] ------ 439.2548 [Hz]
- 22000 [samples/s] ------ 439.2548 [Hz]
- 44100 [samples/s] ------ 440.0848 [Hz]

In fact, I just found in Matlab "...standard audio

rates are 8000, 11025, 22050, and 44100 Hz...", 101205

The rest of the SamplingRates in between give a wrong answer. I ran an experiment were a frequency generator was playing for a constant period of time, at the same time I’m recording the sound for 0.5 [s] at a given SamplingRate, doing an FFT, and finding the peak, this process will repeat over until the SamplingRate in MatLab is covered (8000 - 44100 [samples/s]). I'll non-dimensionalized the frequency peaks dividing them by the frequency from the frequency generator, so that all the points which are one are correct, and the rest are not.

## Friday, September 09, 2005

### Run5

### Run4

Run4: recordings were taken 55 [ft] down the crest, and about 100 [ft] left from the Run1.Two geophones: I/O 1 Yellow, I/O2 Yellow. HandHeld settings; SamplingRate: 2000 [samples/s], 10000[samples], therefore 5 [s] of recording time.

Problems: One of the geophones wasn't amplifying the signal properly, but the peak on the frequency is the same for both of them.

### 09095

- Place: Dumont Dunes
- Objectives: geophones recordings, sand samples, and resistance probe.
- Difficulties: recording signal with the computer: Changing the sampling frequency modifies the corresponding characteristic frequency. Using the computer to get the booming signal through the mic-jack port is not RELIABLE .
- Experiments and settings:

- Run1: recordings were taken 50 [ft] down the crest, with two geophones: I/O 1 Yellow, I/O2 Blue. HandHeld settings; SamplingRate: 2000 [samples/s], 10000[samples], therefore 5 [s] of recording time.

## Tuesday, September 06, 2005

### More Places

I hope being able to provide more information about those places.