Common Issues and Solutions

Refer to the following table to debug common issues found in an audio and acoustics test system.

Table 10. Common Issues and Solutions in an Audio and Acoustics Test System
Issue Possible Cause Solution
The resistance or the total loss of connection increases. Some parts, such as the electronic contacts that connect a DUT to the test system, are worn. Check the parts and replace them if worn.
The acquired signals are abnormal. The following problems related to hardware components occur:
  • The amplifier input is overloaded.
  • Cables are unplugged.
  • Switches are turned on or off accidentally.
 Provide protection for the system. For example, set the lower and upper limits for input ranges of instruments.
Measurement results are unstable. Temperature significantly affects the electronic parameters of the speaker and microphones. For speaker tests:
  • Use a simulated signal complying with IEC 60268-1:1985 to precondition the speaker before testing in accordance with IEC 60268-5:2003.
  • Reserve a recovery period after precondition.

Before a microphone test, keep a microphone with a preamplifier on for a period specified by the manufacturer in accordance with IEC 60268-4:2018. This allows the microphone to reach the stationary temperature under rated conditions.
The delay is longer than expected. Cables are too long. Use short cables.
The measured noise value is high.
  • Cables are too long.
  • The electromagnetic field affects noise measurements.
  • Use short cables.
  • Use XLR cables and modules with balanced inputs and outputs.
Test results are inconsistent, or repeatability issues occur. There is much acoustic background noise or electric noise.
  • Improve acoustic isolation.
  • Optimize measurement settings, such as signal sweeping duration.
The phase frequency response curve is ramping up or down.
  • Microphones are misaligned.
  • The speaker is too close to and misaligned with the microphones.
  • A delay error occurs.
  • Adjust the position of the reference microphone.
  • Correct the delay error in post processing.
The distortion measured by the reference microphone is higher than expected. The speaker generates a distorted signal.
  • Reduce the SPL.
  • Use a new speaker with better performance.
The fluctuation of magnitude frequency response is greater than expected, especially at high frequencies. The distance between the DUT and reference microphone is too large. Adjust the position of the reference microphone.
The position of the speaker is inappropriate. Adjust the position of the speaker.
A hard surface is too close to the microphones. Reduce the acoustic impacts of fixtures.