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Measurement of PC's soundboard by RA 5
Impulse response measurement

Measurement conditions and the equipments are same as the Audio measurement report 1

This time, the impulse response of a listening room is measured by DELL Inspiron7500 and 8200. These measurements were done after Measurement of PC's soundboard by RA part3, and part4

Impulse response is a transfer function between the signal source and the receiver. When it is measured in a room, the impulse response includes the information of sound reflection, absorption, and reverberation, and it shows the sound quality of a room. 

In RA, the impulse response can be measured by MLS (Maximum Length Sequence) and TSP (Time Stretched Pulse) methods. See the program manual for more information about the impulse response measurement. 

Test of the MLS measurement. Mixer was selected as the input device. It means that I measured the impulse response of the soundcard itself.

Impulse response measured for the listening room. It was measured by the MLS method, with Auto Level and Auto Retry. Result is same as Audio measurement report 2. It is a very noisy response. Auto retry function worked many times. 

Sound file: ra51.wav (44.1kHz / Stereo / 0.743sec / 128KB)

Download the above sound file. Measured impulse response can be listened to. It can be loaded on RA. Click the "Load" button and select the "Wave file". 

Test of the TSP measurement. This is same as the last measurement in Measurement of PC's soundboard by RA part2. There is an unwanted pulse at 80 ms and 160 ms. Perhaps there is some problem in the equipment.

Impulse response measured for the listening room. It was measured by the TSP method. 

Sound file: ra52.wav (44.1kHz / Stereo / 0.743sec / 128KB)

Now, it is measured by Inspiron7500. 

Test of the MLS measurement. Very clean response. 

Test of the TSP measurement. We can see unwanted pulses too. 

Next, Inspiron8200 is tested.

Test of the MLS measurement. There is no problem.


Test of the TSP measurement. There is no problem.

The room impulse response measured by the MLS method. 

Sound file: ra5m.wav (48kHz / Stereo / 0.683s / 128KB)

The impulse response measured by the TSP method. 

Sound file: ra5t.wav (48kHz / Stereo / 0.683s / 128KB)

Test results showed that the soundcard makes some noise even when the Mixer output is measured. But it is no problem in practice. It can be analyzed even if there are some noises. However, when the noise level is high, Auto Retry function works and it takes long time. In that case, use of the TSP method is better. 

July 2003 by Masatsugu Sakurai