Rew acoustic test (V): equipment required for test

REW The equipment required for acoustic testing is a microphone 、 The tripod 、 Sound card 、 Sound level meter 、 Hi Fi speakers 、 Test the computer and connecting cable .

Microphone

Acoustic testing requires equipment that can collect test signals . The device has the following options ：

1. With calibration file USB Microphone .

This microphone can be used for low frequency or full range measurement . If the calibration file also has REW Identify the sensitivity data of the format , It can also be used as a calibrated sound level meter . Recommended MiniDSP UMIK-1, Its calibration data is in REW Internally identifiable .

2. Sound level meter with wired analog output .

Recommended model Radio Shack, Both analog and digital versions of this model are suitable for acoustic measurement in silent rooms .

The tripod

The tiny vibration of the microphone will cause great changes in the measurement results . For tests that need to be repeated many times , It is necessary to fix the microphone for a long time . For low frequency measurements （ Below a few hundred hertz ）, You can set the microphone to point upwards . So you can measure different speakers without moving it , And the reading on the instrument can be easily read . If the point is up , Need to use “90 degree ” Microphone calibration file .

To measure higher frequencies , It is best to point the microphone directly at the speaker under test , under these circumstances , Need to use “0 degree ” Microphone calibration file . In both cases , The microphone should be placed at the ear height of the normal listening position .

Sound card

If you use USB Microphone , The headphone output of the computer can generate REW Test signals used , No sound card required . If you use a sound pressure meter or a microphone with a preamplifier , You need a sound card with line input and line or headphone output （ Inside or outside ）.

Please note that , majority PC And laptop single microphone input is not suitable for signal acquisition （ They have too much gain , Most are affected by high noise and limited bandwidth ）, But the combination microphone / Line input can use . Cheap or built-in sound cards are usually enough , Setting a reference measurement with a loopback connection can offset the sound effect of the sound card from the measurement .

Connecting line

If the microphone is not USB Microphone , You need a cable to connect the microphone to the sound card , And connect the sound card to the test computer . The connector plug needs to be fitted with a sound card and a microphone . If a reference signal is required , Then one input and output are connected in series to form loopback loop .

END